Skywatcher's Almanac/ Astronomical Fact of the Week

Flash's Skywatcher's Almanac
Flash's Astronomical Fact of the Week
 

Flash's Skywatcher’s Almanac
 

Each week, Flash's Skywatcher's Almanac keeps you abreast, for the ten-day period upcoming, of significant happenings in the night sky.  The almanac lists also important anniversary dates in space history.

Visitors are invited to log on each week for an updated almanac.
 

For the ten-day period beginning June 15, 2003

June 16
 

June 17
 

June 18
 

June 19
 

June 20
 

June 21
 

June 22
 

June 24
 

Astronomical data from The Old Farmer's Almanac and Star Date magazine

Historical data from Life in Space (a Time-Life Book), Time Almanac 2003, and The World Almanac and Book of Facts 2003

Space Shuttle data from Air Force magazine and the Space Shuttle Launch site at http://science.ksc.nasa.gov

Supplemental data from the Encyclopedia Astronautica website at http://www.astronautix.com
 
 

Flash's Astronomical Fact of the Week
 

Each week, Flash's Astronomical Fact of the Week presents a brief essay on space science, space exploration, space history, and space personalities.  It is intended to encourage your study of astronomy and enhance your enjoyment of stargazing.

Visitors are invited to log on each week for a new science lesson; and to check out past essays, which are archived on this webpage.
 

For the week beginning August 25, 2002

Flash’s Astronomical Fact #149

In the aftermath of the French Revolution, France adopted a new calendar.  It was called (naturally enough) the French Revolution calendar.

New Year’s Day on the French Revolution calendar was the autumnal equinox (the first day of fall in the Northern Hemisphere).  Thus, the first day of the first month of Year I (that is, Roman numeral one) of the Republic was September 22, 1792.

Probably in keeping with the principal of equality, each of the new calendar’s twelve months had thirty days.  The thirty days were divided into three weeks of ten days each.

The months for each season purposely were given rhyming names, as follows: 

The autumn months were Vendemiaire (Vintage), Brumaire (Mist), and Frimaire (Frost).
The winter months were Nivose (Snow), Pluviose (Rain), and Ventose (Wind).
The spring months were Germinal (Seed), Floreal (Blossom), and Prairial (Meadow).
The summer months were Messidor (Harvest), Thermidor (Heat), and Fructidor (Fruits).

To keep the new calendar in synch with the solar cycle, five or six days were tacked on after the twelfth month to make for a total of 365 or 366 days (depending, of course, on whether the year was an ordinary year or a leap year).  These extra days, called collectively the Sans-culottides, were:

Jour de la Vertu (Day of Virtue).
Jour du Genie (Day of Genius).
Jour du Travail (Day of Labour).
Jour de L’opinion (Day of Reason).
Jour des Recompenses  (Day of Rewards).
Leap Day was Jour de la Revolution (Day of Revolution).

Of course, developing a new calendar is one thing; putting it into effect throughout a relatively large and relatively populous nation like France is another thing entirely.  Moreover, the leaders of the French Revolution had to give priority to overseeing the Reign of Terror and other pressing matters of state.  As a result, the French Revolution calendar did not become operative until November 24, 1793. 

So what became of the French Revolution calendar?  We will examine that question in the next edition of Flash’s Astronomical Facts.

 Source:  The French Revolution Calendar site at http://www.wundermoosen.com
 

For the week beginning August 18, 2002

Flash’s Astronomical Fact #148

As they hurtle through the atmosphere, the vast majority of meteors burn up completely due to air friction. Consequently, most meteors never reach the Earth’s surface. 

But a certain percentage of meteors do survive the fiery plunge to reach the ground.  After a meteor hits the Earth, it is called a meteorite.

As you might imagine, most meteorites are small.  But a handful of meteorites are multi-ton behemoths.

The largest meteorite in the world is located on the African continent in present-day Namibia.  It is called the Hoba Meteorite, named for the farm on which it was discovered.

The Hoba Meteorite is estimated to be between 200 million and 400 million years old, and is believed to have fallen to the Earth some 80,000 years ago.

The Hoba Meteorite weighs 66 tons.  Not only is its weight noteworthy, but so too is its shape.  Most large meteorites are shaped like a potato.  The Hoba Meteorite is cuboid in shape (like a slice of cornbread) and measures 2.95 m (9.68 ft) by 2.84 m (9.32 ft). 

The composition of the Hoba Meteorite is 82.4% iron, 16.4% nickel, and 0.76% cobalt.  The ratio of nickel to iron is unusually high.  Such an iron/nickel meteorite is called a nickel-rich ataxite.

Scientists believe that if the Hoba Meteorite had been any bigger, it would have broken up into many pieces as it plummeted through the atmosphere.  Thus, not only is the Hoba Meteorite the largest on Earth, it is unlikely that any meteorite ever found will be appreciably larger.

The Hoba Meteorite was discovered and first described by a certain J. Brit in 1920.

The Hoba Meteorite was declared a national monument in 1955, but still continued to suffer damage at the hands of vandals.

In 1985, Rossing Uranium, Ltd. donated funds to combat 
vandalism. 

In 1987, the Hoba farm donated the lands surrounding the Hoba Meteorite for educational purposes.  An education center was erected at the site the same year.

The Hoba Meteorite is on display to the public; so, if you are willing to take a trek to Namibia, you can see with your own eyes the world’s largest meteorite.

 Sources:  Voyage Through the Universe/Comets, Asteroids, and Meteorites, a Time/Life Book series, and the Hoba Meteorite site at http://www.namibweb.com
 

For the week beginning August 11, 2002

Flash’s Astronomical Fact #147

The planet Venus is the brightest object in the night sky, save for the Earth’s Moon.  Venus has a maximum apparent magnitude of –4.4, which makes it brighter than any of the other planets in our solar system, and brighter also than any of the true stars.  During its times of greatest brilliancy, Venus shines so brightly that the planet has been mistaken for such objects as orbiting satellites, approaching aircraft, and even flying saucers.

But what is it about Venus that makes it appear so bright in our night sky?

There are four principal factors that account for Venus’ brilliancy.

The first factor is reflectivity.  Venus is enveloped in clouds, the top layers of which are composed primarily of sulfuric acid.  These clouds reflect a large percentage (76%) of the sunlight that falls on them.  In fact, no other planet in the solar system reflects a greater percentage of the sunlight that falls on it than Venus.  The Earth, by comparison, reflects only 33% of the sunlight that falls on it.  Astronomers refer to this reflectivity factor as the planet’s albedo (pronounced al-bee-doh).

The second factor is size.  Venus is a planet, and therefore a relatively large body (of the nine planets, Venus is the sixth largest).  This means that its top cloud layers are relatively large in area, which means in turn that it can reflect relatively large amounts of sunlight. 

The third factor is Venus’ position in the solar system.  Venus orbits second outward from the Sun at a distance of only 107 million km (67 million miles).  Only the planet Mercury orbits closer.  As a result of this relative closeness, the planet Venus is bathed continuously in high concentrations of sunlight.

The fourth factor is the Earth’s position in the solar system.  The planet Earth orbits third outward from the Sun at 150 million km (93 million miles).  Venus can approach closer to the Earth than any other planet in the solar system.  At its closest approach, Venus lies only 43 million km (26 million miles) away.

These four factors combine to make Venus a dazzling sight in our night sky.  Small wonder that the classical civilizations named the planet for their goddess of beauty.

 Sources:  The Venus sites at http://www.seds.org and http://zebu.uorgeon.edu
 

For the week beginning August 4, 2002

Flash’s Astronomical Fact #146

In this edition of Flash’s Astronomical Facts, we will conclude our discussion of the Space Shuttle’s Payload Deployment and Retrieval System by relating a few random facts about the Remote Manipulator System (RMS), popularly known as the “robot arm”.

A special bolt is fitted to the RMS to hold it in place securely during launch.  After achieving orbit, the Space Shuttle crew releases this bolt to enable the robot arm to be put to use.  Interestingly, it is not considered necessary to re-insert the special bolt into the RMS in preparation for re-entry.

The robot arm can never endanger the Space Shuttle and her crew by making it impossible to close the cargo bay doors.  If, for any reason, the RMS cannot be folded properly so as to enable the cargo bay doors to be closed, the crew can jettison part or all of the assembly by releasing special bolts found on all three of the robot arm’s joints. 

As implied above, the RMS is not affixed permanently to the body of the Space Shuttle, but is instead removable.  And not just for the safety reason cited above.  The ability to remove the RMS means that the device need be taken along only on those missions during which it will be needed.  If a particular mission does not require the services of the PDRS, the entire system can be removed, affording a savings in weight at launch of 450 kg (994 lbs).

 Source:  The Payload Deployment and Retrieval System site at http://prime.jsc.nasa.gov
 

For the week beginning July 28, 2002

Flash’s Astronomical Fact #145

Beginning with the July 7, 2002 edition of Flash’s Astronomical Facts, we have been examining the Space Shuttle’s Payload Deployment and Retrieval System (PDRS).

The Remote Manipulator System (RMS) is the active part of the PDRS.  The RMS (or “robot arm”, as it is popularly known) has performed magnificently.  It has deployed satellites from the Space Shuttle’s cargo bay, and retrieved orbiting satellites for repair and re-deployment or for return to Earth.

But how is this amazing system operated?

The RMS is operated by not one, but two, astronauts.  By means of remote control manipulation of the shoulder joint and elbow joint of the robot arm, the first astronaut can extend the booms that constitute the upper arm and forearm of the RMS.  The end effector (grasping mechanism), which corresponds to the hand of the robot arm, is operated by yet another remote control device.

The second astronaut assists the first by operating the closed-circuit television camera mounted on the robot arm’s elbow joint.

The first operator can see what he is doing by looking at the television monitor; or by looking out of the aft flight deck payload windows or the aft overhead windows - all the while remaining safely inside the Space Shuttle’s “shirt-sleeve” environment.

We will conclude our discussion of the Space Shuttle’s Payload Deployment and Retrieval System in the next edition of Flash’s Astronomical Facts.

 Source:  The Payload Deployment and Retrieval System site at http://prime.jsc.nasa.gov
 

For the week beginning July 21, 2002

Flash’s Astronomical Fact #144

In the July 7, 2002 edition of Flash’s Astronomical Facts, we began our examination of the Space Shuttle’s Payload Deployment and Retrieval System (PDRS).  The most important part of the PDRS is its robot arm, known formally as the Remote Manipulator System (RMS).

The robot arm is aptly named, for it truly does resemble a human arm in both form and function.  The robot arm consists of two long booms that serve as the "forearm" and "upper arm".  A "shoulder joint” attaches the upper arm to the cargo bay's interior bulkhead.  An “elbow joint” attaches the upper arm to the lower arm.  A “wrist joint” attaches the lower arm to the “end effector” (grasping mechanism), which corresponds to the "hand".

The joints give the RMS six degrees of freedom (free movement):  Yaw and pitch at the shoulder; pitch at the elbow; yaw, pitch, and roll at the wrist.  These movements combine to enable the robot arm to go anywhere its length permits.

Speaking of length, the RMS has a total length of 15.32 m (50.25 ft).  Each of its booms has a maximum diameter of 38 cm (15 in).  The total PDRS has a weight of 450 kg (994 lbs).  Of that weight, the RMS alone accounts for 410 kg (905 lbs). 

Each of the booms is made of a composite material of graphite bonded with epoxy resins.  The joints are metallic, and the electronic housings are made of an aluminum alloy.

The RMS can handle a payload with a mass of up to 29,500 kg (65,000 lbs).  But significantly, the robot arm can work only in space.  It is too fragile in structure and too weak in power to operate in Earth’s gravity.

I will have more to say about the Space Shuttle’s Payload Deployment and Retrieval System in the next edition of Flash’s Astronomical Facts.

 Source:  The Payload Deployment and Retrieval System site at http://prime.jsc.nasa.gov
 

For the week beginning July 14, 2002

Flash’s Astronomical Fact #143

In the previous edition of Flash’s Astronomical Facts, we began our examination of the Space Shuttle’s Payload Deployment and Retrieval System (PDRS).  The portion of PDRS that is most familiar to the general public is the robot arm, known formally as the Remote Manipulator System (RMS).

When you see the RMS in action on television, you cannot help but notice the small Canadian flag and the word “CANADA” in big bold letters painted in red on one of the booms.  There is a very good reason why those markings are there.

The National Research Council of Canada, in association with NASA, created the RMS.  The Canadian firm of Spar Aerospace Ltd. designed, built, and tested the RMS.  Another Canadian firm, CAE Electronics Ltd., provided the electronic interfaces, servoamplifiers, and power conditioners for the robot arm.  A third Canadian firm, Dilworth, Secord, Meager & Assoc. Ltd., built the specialized “end effector” (grasping mechanism) for the RMS.

Giving the contract for the RMS to Canada was of mutual benefit to both nations.  America gained by spreading the costs of the Space Shuttle project.  Canada gained by becoming a partner in, and acquiring a stake in the success of, the Space Shuttle.

Although Canada does not have a space program comparable to that of the United States, it does recognize the importance of the high frontier and wishes to take an active part in its development. Building the RMS enabled Canadian firms to gain valuable experience in the engineering of space systems.  At the same time, it allowed Canada to contribute to the Space Shuttle project in a significant way. 

And the Canadians are committed to doing more than just manufacturing space hardware.  As of October 1, 2001, nine of the astronauts who have flown aboard the Space Shuttle have been Canadian.

I will have more to say about the Space Shuttle’s Payload Deployment and Retrieval System in the next edition of Flash’s Astronomical Facts.

 Sources:  The World Almanac and Book of Facts 2002 and The Payload Deployment and Retrieval System site at http://prime.jsc.nasa.gov
 

For the week beginning July 7, 2002

Flash’s Astronomical Fact #142

The Payload Deployment and Retrieval System (PDRS) is the formal name for the totality of devices and mechanisms that make it possible for the Space Shuttle to remove payloads from its cargo bay and deploy them into space; or to capture previously deployed objects (such as orbiting satellites) and place them into the cargo bay for repair and re-deployment or for return to Earth.

The active portion of the PDRS - and the part most familiar to the general public - is the Space Shuttle’s robot arm, known formally as the Remote Manipulator System (RMS).

The RMS has three basic functions.  One function is the deployment and retrieval of payloads, as described above. 

The second function of the RMS is to provide a work platform for a spacewalking astronaut.  This is accomplished by attaching special foot restraints to the end of the robot arm.  By placing his boots into the foot restraints, the spacewalking astronaut obtains a steady purchase.

The third function of the RMS is to effect a visual inspection of the Space Shuttle by means of its attached closed-circuit television cameras.

I will have more to say about the Space Shuttle’s Payload Deployment and Retrieval System in the next edition of Flash’s Astronomical Facts.

 Source:  The Payload Deployment and Retrieval System site at http://prime.jsc.nasa.gov
 

For the week beginning June 30, 2002

Flash’s Astronomical Fact #141

What follows is the sixth of an occasional series about flags with stars.

With Independence Day coming up on July 4, this edition of Flash’s Astronomical Facts will present another in its series of flags with stars.

In Flash’s Astronomical Facts #138 (for June 9, 2002), we examined the flag of the state of Rhode Island.  In this edition, we will examine its predecessor colonial battle flag, which had a number of similarities - and differences.

The Rhode Island battle flag was introduced in 1772.  The field of the flag was white.  The principal design element was a blue anchor.  An anchor line, also blue in color, snaked artistically around the shaft of the anchor.  Arcing above the anchor was a ribbon of blue on which the word HOPE (Rhode Island's state motto) was written in large white block letters.

The most significant design element of the Rhode Island colonial flag was the canton (union) of blue in the upper left-hand portion of the flag.  Placed in the canton were thirteen five-pointed stars (pentagrams) intended to represent the Thirteen Original Colonies.  The Rhode Island battle flag was the first to use stars in this way.  The stars were gold in color (or silver, or white, depending on which source you access). 

Even more significantly, the Rhode Island colonial flag was the first to arrange the stars within its canton in a stylized pattern.  The stars were arranged in a row of three above a row of four above two rows of three (3-4-3-3), or a pattern of three rows of three alternating with two rows of two (3-2-3-2-3) (again, depending on which source you access).  The latter pattern is significant because the same pattern later would be used on the first flag of the United States.

Rhode Islanders were among the strongest advocates of the Revolutionary cause, and got in the act early.  On June 10, 1772, Rhode Islanders took action against the British revenue cutter Gaspee.  Although the burning of the Gaspee will not be examined in detail in this essay, it is worth studying, as it was one of the first actions taken by American colonists in defiance of British authority.

 Sources:  An Album for Americans, by David H. Appel, the Gaspee site at http://www.gaspee.com, and the Flags site at http://www.anyflag.com
 

For the week beginning June 23, 2002

Flash’s Astronomical Fact #140

Way back when, manned space flight was the undertaking of only two nations:  The United States and the Soviet Union.  Consequently, the only humans in space were either Americans or Russians.

Nowadays, any nation can participate in the exploration of outer space - and without having to develop a full-fledged space program in order to do so.  The International Space Station is now in orbit, with the American Space Shuttle and the Russian Soyuz employed to ferry personnel and materiel aloft.  Thus, a country that wishes to become part of the space effort does not have to have launch facilities, space vehicles, and orbiting space stations of its own.  It need only have its best scientists apply for astronaut training.

During the first forty years of manned space flight (1961-2001), 422 individuals took at least one trip into space.  As of October 1, 2001, here is how the numbers break down by nationality:  United States, 267; Russia (both the old U.S.S.R. and the new C.I.S.), 97; Germany (West, East, and United), 11; Canada, 9; France, 8; Japan, 5; Italy, 3; two each for Bulgaria and Spain; and one each for Afghanistan, Austria, Belgium, Cuba, Czechoslovakia, Hungary, India, Mexico, Mongolia, the Netherlands, Poland, Romania, Saudi Arabia, Slovakia, Switzerland, Syria, the United Kingdom, and Vietnam.

Doubtless, astronauts from many more nations will be sent aloft in the years to come.  Stay tuned. 

 Source:  The World Almanac and Book of Facts 2002
 

For the week beginning June 16, 2002

Flash’s Astronomical Fact #139

The Zuni Indians of the southwestern region of North America have an interesting legend about the Sun, the Moon, and the seasons.

It is said that when the world was young, the sky was always dark and the Earth was always hot (that is, it was always summer).

One day, the coyote and the eagle decided to go hunting together.  In due course, they came upon the powerful Kachinas people.  From the Kachinas, the coyote and the eagle learned the reason why the sky was always dark and the Earth was always hot.  The Kachinas had captured both the Sun and the Moon, and were holding them prisoner inside of a box.  With the Sun so close to the Earth, it was no wonder that it was always summer!

The coyote and the eagle decided that they would steal the box.  They waited for the Kachinas to lie down to sleep, then made their move.

The eagle tried to carry the box by himself.  But the box proved to be too heavy for the eagle, so the coyote offered to carry it.  But unlike his brother the eagle, the coyote was curious.  The coyote opened the box, which allowed the Sun and the Moon to escape.  Both bodies rose up into the sky. 

As a consequence of the Sun ascending into the heavens, light fell upon the land, putting an end to the perpetual darkness.  But with the Sun now so far above the Earth, there was less heat upon the land.  And thus was born the season of winter.

 Source:  The Solar Legends site at http://solar-center.stanford.edu
 

For the week beginning June 9, 2002

Flash’s Astronomical Fact #138

What follows is the fifth of an occasional series about flags with stars.

With Flag Day coming up on June 14, this edition of Flash’s Astronomical Facts will examine another flag that contains stars.

One of the most star-spangled of all state flags is that of the state of Rhode Island (known fully as the State of Rhode Island and Providence Plantations).  The flag was adopted by the Rhode Island state legislature at its January 1897 Session.  This made it the third of the Original States (after New Jersey and New York (in 1896)) to officially adopt a state flag.

Although it appears to be perfectly square in shape, the official Rhode Island state flag actually has a fly (length) of five foot six inches and a hoist (height) of four foot ten inches.  The flag’s field is white.  In the middle of the white field is an anchor of gold.  Beneath the anchor is a ribbon of blue, on which the word HOPE (Rhode Island's state motto) is written in gold block letters.  Surrounding the anchor and ribbon is a circle of thirteen gold stars, one for each of the Thirteen Original Colonies.

The design elements on the Rhode Island state flag pre-date the American Revolution.  Under the authority of the Cromwellian Patent of 1643, the Providence Plantations adopted (in 1647) the anchor as the official seal of the Province.  Later, under a more liberal charter granted by King Charles II of England to the Colony of Rhode Island and Providence Plantations, the word HOPE was added above the anchor.

The circle of stars on the Rhode Island state flag is another design element that pre-dates American Independence.  Several battle flags of the American Revolution bore a circle of stars.

The flag's colors also pre-date the American Revolution.  Blue and white have long been Rhode Island's official colors (hardly surprising, being as it is a coastal state).  Blue and white have appeared on state regimental banners carried by Rhode Islanders into such conflicts as the American Revolution, the War of 1812, and the Mexican War.

As in other states, the design of the Rhode Island state flag is defined in Rhode Island statutory law; but that law contains several peculiarities.  For one thing, Rhode Island law expressly requires that the flag be trimmed with decorative yellow fringe (in most states, the use of the decorative fringe is optional).  Moreover, in most states, the pike (staff) from which the flag flies may be surmounted by any number of decorative devices (ball, star, spear, flat truck, eagle, halberd, etc.).  But Rhode Island law states that the pike must be surmounted by a spear.  Finally, the law defines even the official height of the pike (9 feet). 

I guess it can safely be said that Rhode Islanders leave nothing to chance.

 Sources:  The Rhode Island flag sites at http://www.netstate.com and http://www.state.ri.us
 

For the week beginning June 2, 2002

Flash’s Astronomical Fact #137

In the previous edition of Flash’s Astronomical Facts, we examined the metallic element beryllium.

Because beryllium is relatively scarce in the Earth’s crust and hard to extract from ore, it is a very expensive metal; far too expensive to use in everyday applications. 

However, there are certain applications for which beryllium is indispensable.  And one such specialized application played an important role in the early days of the space program.

In passing through the Earth's atmosphere, most meteors burn up completely - and long before reaching the Earth's surface - due to the heat generated by atmospheric friction.  And exactly the same fate would befall a space capsule and her crew upon re-entry – unless precautions were taken to prevent it.

That is where beryllium comes in.

Beryllium has a number of properties that made it the metal of choice to protect Mercury capsules from the heat of re-entry.  First, beryllium is very light in weight.  In fact, beryllium is the second lightest of all the metals.  And the less that something weighs, the less the amount of fuel required to send it into orbit.

Not only is beryllium light in weight, it has one of the highest melting points of all the lightweight metals.  Aluminum, for instance, melts at 660 degrees C.  By contrast, beryllium melts at a whopping 1278 degrees C!

And as if that were not enough, beryllium has one of the highest specific heats of all the metals.  A complete explanation of the concept of specific heat is beyond the scope of this essay.  But here is the practical upshot:  A substance with a high specific heat can absorb large amounts of heat while increasing in temperature only slightly.

And far from being an untested commodity, beryllium already had proved itself to be an effective and efficient absorber of heat.  Years before the beginnings of manned space flight, the U.S. Navy had used beryllium to absorb heat on selected parts of unmanned Polaris missiles.

Given all of its intrinsic qualities, coupled with its proven track record, it is little wonder that beryllium - in the form of a heat shield fitted to the underside of the spacecraft - was called upon to protect Mercury capsules from burning up during re-entry.

And protect them it did.  During re-entry, the beryllium heat shield absorbed almost all of the heat generated by atmospheric friction, leaving almost none to endanger the Mercury craft and her occupants.  This technique of protecting space capsules from the heat of re-entry is called heat sink or - more fully -beryllium heat sink.

Capsules in the successor Gemini series used a different method of protecting the spacecraft from the heat of re-entry.  But we will examine that technique in a future edition of Flash’s Astronomical Facts.

 Sources:  CRC Handbook of Chemistry and Physics, the Beryllium sites at http://www.osha-slc.gov and http://www-tech.mit.edu, and the Beryllium Heat Sink site at http://www.hq.nasa.gov
 

For the week beginning May 26, 2002

Flash’s Astronomical Fact #136

Metals are a class of chemical elements characterized by such properties as malleability, strength, and the ability to conduct heat and electricity.  Without metals, modern civilization would be impossible.

Different metals have different properties, and it is a metal's properties that determine how it is used.  Copper, for example, is an excellent conductor of electricity, and is found in everything from power generators to house wiring.  Lead is extremely dense, and is useful as a radiation shield.  Iron is incredibly strong, and can be used to build tall structures (such as the Eiffel Tower). Aluminum, light in weight, is found in everything from kitchen utensils to aircraft bodies.

The average individual is familiar with the above metals because they are relatively abundant, fairly easy to refine, and frequently encountered in the course of everyday life.

But there are other metals with which members of the general public are not as familiar.  These metals are relatively scarce, quite difficult to refine, and seldom encountered in the course of everyday life.

One such metal is beryllium.

Beryllium - the principle ores of which are beryl, phenacite, and chrysoberyl - is relatively scarce in the Earth’s crust at just six parts per million.  Moreover, the processes required to extract the metal from ore are chemically complex and can be accomplished only under high temperatures and pressures. 

As a consequence, beryllium is a relatively expensive metal.  While most refined metals sell for just pennies per kilo, pure beryllium metal retails for over $5,000 per kilo (over $2,000 per pound)!

While beryllium might be used for a number of everyday applications, less expensive metals that can serve the same purpose are used instead.

However, there are certain applications for which beryllium is indispensable.  And one such specialized application played an important role in the early days of the space program.  We will examine that aspect of beryllium in the next edition of Flash’s Astronomical Facts.

 Sources:  CRC Handbook of Chemistry and Physics, Webster's New World Dictionary, the Eiffel Tower site at http://www.tour-eiffel.fr, and the Beryllium sites at http://www.osha-slc.gov and http://www-tech.mit.edu
 

For the week beginning May 19, 2002

Flash’s Astronomical Fact #135

In April of 1959, seven men were selected to become Mercury astronauts.  But there were only six manned flights in the Mercury series.  Obviously, someone with “The Right Stuff” did not get to fly a Mercury mission.

And that someone was U. S. Air Force Captain Donald K. “Deke” Slayton.  In August of 1959, just four months after becoming one of America's charter space pioneers, Slayton underwent medical tests that revealed that he had an irregular heartbeat.  Grounded by his cardiac condition, Slayton would never fly a Mercury mission.  One can only imagine how profound must have been the depths of his disappointment. 

But hey, no need to feel too sorry for Slayton.  After getting his heart problem under control, he was selected for another mission into space - a mission that would turn out to be one of a kind. 

Slayton was chosen to be one of the three astronauts to fly the American portion of the historic Apollo/Soyuz joint mission.  Astronaut Thomas Stafford commanded Slayton and astronaut Vance Brand.  The Soviet portion consisted of cosmonaut Alexei Leonov commanding cosmonaut Valeriy Kubasov.

Besides accomplishing its scientific and diplomatic objectives, the Apollo/Soyuz joint mission must surely have compensated Slayton for whatever disappointments he might have felt at having been denied a Mercury flight .  For one thing, Slayton and his fellow astronauts shared the honor of flying the last Apollo mission (the Apollo capsule was retired from service following theApollo/Soyuzjoint mission).

But Slayton got another honor; and it was one that he did not have to share with anyone.  At the time of the Apollo/Soyuz joint mission, Slayton was 51 years of age.  This made him the oldest man (up to that time) ever to take a trip into space.

Thanks to the Apollo/Soyuz joint mission - which lasted from July 15 to July 24, 1975 - Slayton logged 217 hours and 28 minutes “out there”.  Not too bad - especially for a man who, at one time, was seemingly destined never to venture into space at all.

I will have more to say on the Apollo/Soyuz joint mission in future editions of Flash’s Astronomical Facts.

 Sources:  Time Almanac 2002, Life in Space (a Time/Life book), the Deke Slayton site at http://www.jsc.nasa.gov, and the National Aviation Hall of Fame site at http://www.nationalaviation.org
 

For the week beginning May 12, 2002

Flash’s Astronomical Fact #134

In 1985, Mexican astronaut Rodolfo Neri Vela requested that one of his favorite foods - soft flour tortillas - be included in the Space Shuttle’s food manifest as one of his optional menu items.

Unfortunately, his request could not be granted.  Way back when, NASA decided to put neither a refrigerator nor a freezer in the Space Shuttle’s galley.  This resulted in the saving of much precious weight and space.  But it meant also that only those foods that did not require refrigeration could be sent aloft aboard the Space Shuttle.

A typical Space Shuttle mission lasts seven days. Coincidentally, that is also the amount of time that it takes for soft flour tortillas stored at room temperature to begin to spoil.  Since it could not be guaranteed that soft flour tortillas would remain edible for the duration of a typical mission, soft flour tortillas were out as a food for Space Shuttle astronauts.

But that was then, this is now   Present-day Space Shuttle astronauts can have soft flour tortillas as part of their diet - because NASA food scientists put their heads together and developed a soft flour tortilla with a shelf life of six months!

This is not to say that NASA food scientists are miracle workers.  For all their efforts, they have yet to find a way to shelf-stabilize one of the world’s favorite snack foods – pizza!

 Source:  Ad Astra magazine, May/June 2002

Ad Astra magazine is a bimonthly publication of the National Space Society, an organization dedicated to the exploration and development of space.
 

For the week beginning May 5, 2002

Flash’s Astronomical Fact #133

Many aspects define the orbit of a satellite.  In the previous edition of Flash’s Astronomical Facts, we discussed the aspect of orbital altitude, or height above the surface of the Earth.  In this edition, we will discuss another aspect, called orbital inclination.

In this context, inclination refers to the tilt of the satellite’s orbit around the Earth.  This tilt, by convention, is measured in degrees relative to the Earth’s equator.

Although a satellite can be made to orbit the Earth at any inclination desired, three special orbital inclinations have proved to be the most useful.

The first of these useful orbital inclinations is the equatorial orbit.  An equatorial orbit, as the term implies, means that the satellite orbits above our planet's equator.  A satellite in equatorial orbit will have an inclination of either 0 degrees or 180 degrees, the difference being this:  If the orbit has an inclination of 0 degrees, it means that the satellite is orbiting above the equator in the prograde direction (that is, west to east, with the rotation of the Earth).  If it has an inclination of 180 degrees, it means that the satellite is orbiting above the equator in the retrograde direction (that is, east to west, against the rotation of the Earth).

Global communications satellites typically are placed in prograde equatorial orbit AND at the geosynchronous orbital altitude of 35,786 km (22,241 miles).  A communications satellite in such an orbit will stand above the same patch of the Earth at all times, thus enabling it to stay in continuous contact with its ground transmission and receiving stations.

Another useful orbital inclination is the polar orbit.  A polar orbit, as the term implies, means that the satellite passes alternately over the Earth’s north and south geographic poles. A satellite in polar orbit will have an inclination of 90 degrees. 

Weather satellites typically are placed in polar orbit AND at an orbital altitude of about 850 km (530 miles) above the Earth’s surface (a satellite orbiting our planet at such an altitude is said to be in Low Earth Orbit).

Why are weather satellites made to orbit the Earth in that way?  Certainly, the low altitude enables the satellite to take clear, close-up shots of our planet’s weather systems.  That is part of the reason.

But in addition, a polar orbit enables a single weather satellite to collect images and data from the entire surface of the Earth.  This is because a polar orbit stands at right angles to the Earth's rotation. 

While the weather satellite moves in its orbit from one pole to the other, its downward-directed cameras and sensors collect images and data from the section of the Earth directly beneath it.  At the same time, the Earth rotates on its axis from west to east.  Thus, on each successive orbit, the satellite gathers images and data from the section of the Earth just to the west of the one previous. 

The images and data are then transmitted to ground receiving stations, where meteorologists assemble the sections into a weather map.  Because the satellite gathers images and data on both sides of the Earth with each orbit, the weather map is never more than twelve hours old.

The last of these useful orbital inclinations is the heliosynchronous (a.k.a  Sun-synchronous) orbit. Literally translated from the Greek, heliosynchronous means “in time with the Sun”.  A satellite in heliosynchronous orbit maintains at all times the same angle with respect to the Sun.  A heliosynchronous orbit has an inclination of 98 degrees, which means that its orbit is near polar and in the retrograde direction. 

A heliosynchronous orbit is tricky to achieve, as it requires not only the right orbital inclination, but also the right orbital altitude and the right orbital eccentricity (that is, its orbit must be an ellipse of the proper shape).  However, it is well worth the effort, because a satellite in heliosynchronous orbit stays continuously above the lighted half of the Earth.  And since good lighting makes for good imaging, a heliosynchronous orbit is exactly where you would want to place a vital observation satellite - such as a military satellite.

 Sources:  Air Force Magazine Space Almanac 2001, and the Satellite Orbit sites at http://www.thetech.org, http://noaasis.noaa.gov, http://physics.uwstout.edu, http://octopus.gma.org,  http://scienceworld.wolfram.com, and http://eesurrey.co.uk
 

For the week beginning April 28, 2002

Flash’s Astronomical Fact #132

Hundreds of artificial (man-made) satellites revolve around the Earth.  Each satellite follows its own unique path - called its orbit – as it circles our planet. 

Many aspects define a satellite in orbit.  And one of the most significant of these aspects is its orbital altitude (that is, its height above the Earth's surface).

Those who are charged with launching satellites into orbit speak of four distinct orbital regions, as described below.

Low Earth Orbit (LEO) refers to those orbits that are closest to the Earth.  A satellite in LEO usually has an orbital altitude in the range of 250 – 300 km (150 - 180 miles) above the surface of the Earth. 

Actually, LEO can range from as little as 100 km (60 miles) to as much as 1000 km (600 miles) above the Earth's surface; but a satellite in orbit would encounter difficulties at either of these extremes.  The more the satellite's orbit drops below the optimum range described in the preceding paragraph, the greater the atmospheric drag on the satellite.  The more the satellite's orbit rises above the optimum range, the greater the disruptive effects on the satellite from the radiation of the Earth’s enveloping Van Allen belts.

Weather satellites typically are placed in LEO so that they can obtain close-up views of the Earth’s weather systems.

Geosynchronous Earth Orbit (GEO) refers to the orbit at which a satellite’s orbital velocity matches precisely the Earth’s rate of rotation.  This orbital altitude is 35,786 km (22,241 miles) above the surface of the Earth.  Geosynchronous, literally translated from the Greek, means “in time with the Earth”.  A satellite that is in GEO  - and orbiting above the Earth’s equator  - will stay above the same patch of the Earth’s surface at all times.

As noted above, LEO consists of a wide range of orbital altitudes.  But GEO consists of only a very narrow range.  Move only a short distance away (in either direction) from the orbital height of 35,786 km (22,241 miles), and the orbit no longer will be geosynchronous.

A handful of weather satellites are placed in GEO so as to get a wider overall picture of the Earth’s weather patterns. But most of the satellites that are placed in GEO are those that provide global communications.  A geosynchronous orbit allows a communications satellite to stay in continuous contact with its ground transmission and receiving stations.

Medium Earth Orbit (MEO) consists of the region between LEO and GEO.  Few satellites are placed in MEO because of the presence of the Van Allen belts, the radiation from which can play havoc with humans and electronics alike (before you ask, Apollo astronauts on their way to, or returning from, the Moon were able to pass safely through the Van Allen belts because they did so quickly).

High Earth Orbit (HEO) is anything above GEO.  Satellites in HEO usually are placed at such heights in order to investigate interplanetary phenomena, such as the solar wind.

In the next edition of Flash’s Astronomical Facts, we will examine another aspect of satellite orbits – their inclinations.

 Sources:  Air Force Magazine Space Almanac 2001, Webster’s New World Dictionary, and the Satellite Orbit sites at http://www.thetech.org, http://eesurrey.co.uk, and http://scienceworld.wolfram.com
 

For the week beginning April 21, 2002

Flash’s Astronomical Fact #131

The great German astronomer Johannes Kepler (1571-1630) determined the physical laws that govern the orbital motions of the planets.  We examined Kepler’s Third Law of Planetary Motion in Flash’s Astronomical Fact #48 (for September 17, 2000).  In this edition, we will examine Kepler’s First Law of Planetary Motion. 

By analyzing the observational data bequeathed to him by the Danish nobleman and amateur astronomer Tycho Brahe (1546-1601), Kepler found that the orbit of the planet Mars was not circular.  Rather, its orbit had the shape of a slightly flattened circle.  Such a geometric figure is called an ellipse.  Moreover, Kepler found that the Sun did not lie at the exact center of Mars’ elliptical orbit, but instead lay offset from the center at one of the ellipse’s two focal points, called foci. 

Kepler later determined that all of the planets in the Solar System have elliptical orbits – including the Earth.

This discovery brought Kepler much relief .  For years, he had been operating on the assumption that the planets have orbits that are perfectly circular.  And for years, he had been driving himself batty trying to make his circular orbit hypothesis fit the observational data.

Kepler's First Law of Planetary Motion may thus be stated as follows:  The orbits of all planets are elliptical, with the Sun located at one of the two foci of the ellipse.

Additional information:  Because the Sun lies offset from the center of a planet’s elliptical orbit, it means that there will one point - and only one point - where the planet will be farthest from the Sun.  This point is called aphelion.  Likewise, there will one point - and only one point - where the planet will be nearest to the Sun.  This point is called perihelion.

We will examine Kepler's Second Law of Planetary Motion in a future edition of Flash's Astronomical Facts.

 Source:  Cosmos by Carl Sagan 
 

For the week beginning April 14, 2002

Flash’s Astronomical Fact #130

Do you enjoy playing word games (Scrabble, Anagrams, and the like)?  Well then, here is a doozy of a word for you:  Syzygy (pronounced "ziz-uh-gee").

Syzygy is the shortest word in the English language that contains three letters ‘y’.  Syzygy comes from syzygia, meaning “yoked” or “paired”.  The word comes to us from Greek via Late Latin.

Syzygy refers to an alignment of celestial bodies, but is used almost exclusively to refer to alignments between the Sun, the Moon, and the Earth.

Originally, syzygy described an alignment where the Moon was at conjunction (that is, positioned between the Sun and the Earth).  The Moon thus had the Sun on one side and the Earth on the side opposite, hence the references to yokes and pairings.  When the Moon is at conjunction, it is at the phase called New Moon, where its lighted half faces fully away from the Earth.

Later on (and almost in defiance of its etymology), syzygy came to refer also to alignments where the Moon was at opposition (that is, positioned on the side opposite the Sun as seen from the Earth).  When the Moon is at opposition, it is at the phase called Full Moon, where its lighted half faces fully towards the Earth.

And what is the significance of syzygy?  For one thing, when the Sun, the Moon, and the Earth are at syzygy (in either of its two forms as described above), gravitational effects are at their maximum, and the highest ocean tides occur.

 Sources:  The Weird Words site at http://www.worldwidewords.org, the Tides site at http://csep10.phys.utk.edu, and Webster’s New World Dictionary
 

For the week beginning April 7, 2002

Flash’s Astronomical Fact #129

Over the course of the next several weeks, skywatchers will be treated to a rare celestial event.  Every planet in the Solar System that is visible to the unaided eye will line up the western sky immediately after sunset.  Mercury will be close to the horizon.  Just above Mercury you will find Venus.  Followed in turn by Mars, Saturn, and Jupiter.

As if that were not enough, the waxing crescent Moon will flirt with each planet in turn.  The Moon will be near Mercury on the 13th; Venus on the 14th; Mars on the 15th; Saturn on the 16th; and Jupiter on the 18th. 

And there is yet more.  On the 16th, people living in certain areas will see the Moon occult (pass in front of) Saturn.

 Sources:  The Old Farmer’s Almanac (2002 edition) and Time Almanac 2002
 

For the week beginning March 31, 2002

Flash’s Astronomical Fact #128

Triton, the largest of Neptune’s eight known natural satellites, has the distinction of having the coldest surface temperature of any object in the Solar System.  The surface temperature of Triton is -235 degrees Celsius (-391 degrees Fahrenheit).  By comparison, the coldest temperature possible - called absolute zero - occurs at -273.15 degrees C (-459.67 degrees F).

So just what is it about Triton that makes it so cold?

Simply put, Triton is cold because circumstances make it nearly impossible for the satellite either to acquire or retain heat.

For starters, Triton - which orbits some 330,000 km (205,000 miles) above Neptune’s cloud tops - receives very little heat from its mother world, which is an extremely cold body in its own right.  The mean temperature of Neptune’s cloud cover is -193 degrees C (-315 degrees F). 

In addition, Triton lies far away from the Sun.  Triton is, as I said, a moon of Neptune; and Neptune orbits the Sun at a mean distance of 4.6 billion km (3 billion miles).  The Sun, to be sure, puts out enormous amounts of radiant energy.  But the farther away from the Sun an object lies, the less of the Sun's energy it receives.  Moreover, this decrease is not linear, but in fact squared.  Thus, situated as it is near the outer edge of the Solar System, Triton receives very little of the Sun's heat and light. 

But the biggest single reason why Triton is so cold is because its surface is so bright.  And bright surfaces are reflective surfaces.  Estimates vary, but Triton reflects at least 60% to as much as 95% of the sunlight that falls on it (by comparison, the Earth reflects only about 30% of the sunlight that falls on it).  In other words, not only does Triton receive virtually no sunlight, it reflects back into space almost all of what little it does receive.

When you consider all that Triton has going against it, it is actually astounding that the satellite is as warm as it is!

 Sources:  The Triton and Neptune sites at http://www.seasky.org, the Earth Albedo site at http://eosweb.larc.nasa.gov, and Time Almanac 2002
 

For the week beginning March 24, 2002

Flash’s Astronomical Fact #127

In the study of astronomy, the word “retrograde” has two different meanings, one of which we will examine here.

If you could look down at the Solar System from a point high above the Earth’s North Geographic Pole, you would see the Earth spinning on its axis counter-clockwise.  This west-to-east motion is what causes the Sun to appear to rise in the east and set in the west.

If you were then to look down at the other planets in the Solar System, you would see that five of them – Mercury, Mars, Jupiter, Saturn, and Neptune – also have a counter-clockwise spin.  Since they have a west-to-east motion like the Earth, these five planets are said to have prograde rotation.  The word “prograde” comes from a couple of Latin roots that mean “to step forward”.

However, three planets in the Solar System – Venus, Uranus, and Pluto – have a clockwise spin.  Since their east-to-west motion is the opposite of the Earth’s west-to-east motion, these three planets are said to have retrograde rotation.  The word “retrograde” comes from a couple of Latin roots that mean “to step backward”.

The terms prograde and retrograde apply also to other planetary motions.  Looking down again at the Solar System, you would see that the Earth revolves around the Sun in a counter-clockwise direction.  So too does every other planet in the Solar System.  Therefore, all of the other planets are said to have prograde revolution.  If, hypothetically speaking, a planet revolved around the Sun in a clockwise direction, it would be said to have retrograde revolution.

And what applies to planets orbiting the Sun applies also to satellites orbiting planets.  For instance, Phoebe, one of the moons of Saturn, revolves retrograde relative to its sibling satellites and the rotation of its mother world.  This retrograde movement suggests strongly that Phoebe did not form with Saturn.  Instead, Phoebe probably was an asteroid that wandered too close to Saturn and was captured by the planet's gravity .

By the way, the word “direct” sometimes is used in place of the word “prograde”.  Astronomers use both terms.  They are equal and interchangeable.

We will examine the other meaning of the word retrograde in a future edition of Flash’s Astronomical Facts.

 Sources:  The Retrograde Rotation sites at http://www.go.ednet.ns.ca and http://www.bartleby.com, Time Almanac 2002 and Webster’s New World Dictionary
 

For the week beginning March 17, 2002

Flash’s Astronomical Fact #126

The Earth is approaching a special orbital position called the vernal equinox.  On March 20, 2002, at precisely 2:16 p.m. EST, the Sun will cross the Earth’s celestial equator from south to north.  Thus, March 20, 2002 will be the first day of spring in the Northern Hemisphere and the first day of fall in the Southern Hemisphere.

In the previous edition of Flash’s Astronomical Facts, I set the record straight regarding a myth associated with the vernal equinox; specifically, that on the first day of spring, it is possible for someone situated on the equator to stand a raw egg upright on its large end (see Flash’s Astronomical Facts #125 (for March 10, 2002) for the details).  In this edition, I will clear up another misconception about the vernal equinox.

It is popularly believed that, on the first day of spring (or the first day of fall), daytime and nighttime last exactly twelve hours each all across the globe.

Certainly, it is understandable why one would suppose that this is so.  At the equinoxes, the Earth presents its Northern and Southern Hemispheres equally to the Sun.  Moreover, the word “equinox” is Latin for “equal night” (which implies, by extension, equal day).

But, however intuitively correct this popular belief may seem, it is simply not true. 

Were you to refer to a detailed almanac (such as The Old Farmer’s Almanac, one of my best sources), you would find that the length of the day (defined as the period of time between sunrise and sunset) is closer to twelve hours on a date several days before, rather than on, the first day of spring.  A similar thing happens around the time of the autumnal equinox.  The length of the day is closer to twelve hours on a date several days after, rather than on, the first day of fall.

Why should this be?

It is the consequence of two factors, both of which are responsible – each in its own way – for making the period of daytime slightly longer than it otherwise would be.

Factor one:  The Sun is a relatively large body that lies relatively close to the Earth.  Therefore, it appears in our sky not as a pinpoint of light, but rather like a disc.  Sunrise, as defined by astronomers, does not begin when the middle of the disc appears above the horizon, but rather when the first portion of the Sun’s disc (called the leading limb) appears above the horizon. Similarly, sunset does not occur when the middle of the Sun’s disc drops below the horizon, but rather when the last portion of the Sun’s disc (called the trailing limb) drops below the horizon.

Daylight is thus extended by a few minutes at sunrise and a few minutes at sunset.

Factor two:  The Earth has an atmosphere.  The atmosphere refracts (bends) sunlight.  Sunlight appearing over the horizon is refracted by about one-half of one degree.

Thus, when we first see the Sun emerge over the horizon at sunrise, we are not seeing the Sun itself, but rather its refracted image.  The Sun is actually below the horizon.  A similar thing happens at sunset.  When we see the Sun on the horizon, we are not seeing the Sun itself, but again, its refracted image. Again, the Sun is actually below the horizon.

Refraction thus extends daylight by a couple of minutes each day.

And so, at the equinoxes, daytime and nighttime are not equal in length.  On the first day of spring (or the first day of fall), daytime lasts twelve hours plus the minutes of extended daylight resulting from factors one and two.  Nighttime lasts twelve hours minus the minutes of extended daylight resulting from factors one and two.

 Sources:  The Old Farmer’s Almanac (2002 edition) and the Astronomy site at http://scienceworld.wolfram.com
 

For the week beginning March 10, 2002

Flash’s Astronomical Fact #125

The vernal equinox is the name given to one of two points in the Earth's orbit where the plane of the Earth's celestial equator intersects the plane of the Earth's orbit.  The Earth will not attain this orbital position for another ten days. But I wanted to get a little ahead of the curve in order to refute a widely-held notion about this celestial event, which marks the first day of spring in the Northern Hemisphere.

A popular myth states that, on the day of the vernal equinox, it is possible for a person situated on the equator to stand a raw egg upright on its large end.  At the vernal equinox, the Sun lies across the Earth's equator, creating a gravitational balance so perfect as to make this feat possible - or so the believers contend. 

But this myth is exactly that - a myth.  It has no foundation in science.  It is completely untrue.

Let me be clear about what I am saying.  It is indeed possible to get an egg to stand upright; but the position of the Earth’s equator relative to the Sun has absolutely nothing to do with it.

The simple truth is, if you hold an egg upright on a level surface long enough for its fluid interior to come to rest, the egg can remain standing on its end indefinitely.  Generations of school children have put this "equinoctial egg theory" to the test in science class.  Students have managed to get an egg to stand upright at any latitude, at any time of the year (including the solstices), and even on the small end!  Moreover, some classes have claimed that after getting their eggs to stand upright, the eggs remained in that position for days, weeks, even months (although I doubt that they would want to use those same eggs to cook a congratulatory omelet).

But if this notion is so flat-out wrong, why does it persist?

Could be for a lot of reasons.  For one thing, the vernal equinox takes place around the time of Easter.  The egg and the resurrection of Jesus long have represented (each in its own way) eternal life.  The Easter connection may explain also why nothing is heard of this “upright egg” myth around the time of the autumnal equinox (the first day of fall in the Northern Hemisphere), where - once again - the plane of the Earth's celestial equator intersects the plane of the Earth's orbit.

Mostly though, I imagine that the myth persists because there is a certain delightful whimsy about the idea of the cosmos occasionally coming into a configuration that enables us lowly humans to perform seemingly impossible feats.

In any case, as long as you know and accept the truth as truth, then the misconception can do you no harm.  In fact, this is one of those cases where knowing the truth seems only to make the misconception all the more delightful.

 Sources:  The Egg and the Equinox sites at http://webs.wichita.edu, http://www.badastronomy.com, http://www.straightdope.com, http://www.usatoday.com, and http://www.clarkfoundation.org 
 

For the week beginning March 3, 2002

Flash’s Astronomical Fact #124

What follows is the first of an occasional series about series of spacecraft.

Pioneer is the designation for the first U.S. series of sophisticated interplanetary spacecraft.  The earliest Pioneer missions were conducted in association with the International Geophysical Year (IGY) of 1957-1958.

As I noted in this week’s edition of Flash’s Skywatcher’s Almanac, March 3, 1959 was the date on which Pioneer IV was launched.  Pioneer IV took the honor of being America's first successful deep-space probe.  But, as you are about to read, several earlier probes in the Pioneer series took mostly a lot of arrows.

The first attempt by the United States to launch a deep-space probe occurred on August 17, 1958.  This mission, which later would be named Pioneer 0, did not go well. 77 seconds after liftoff, the first stage exploded.

Pioneer I was launched on October 11, 1958.  Although the rocket launch was successful, the probe failed to achieve escape velocity (the speed necessary to break free of the Earth’s gravitational pull) and attained a maximum altitude of only 113,800 km (70,700 miles).  Thus, Pioneer I did not make it even one-third of the way to the Moon.  This is not to say that the mission was a complete bust, however.  Instruments aboard Pioneer I were able to determine the radial extent of the Van Allen radiation belts, make the first examinations of the Earth’s magnetic field and of interplanetary magnetic fields, and take the first measurements of the concentration of micrometeorites in interplanetary space.

The launch of Pioneer II on November 8, 1958 ended in disaster when the third and fourth stages failed to separate. Pioneer II attained a maximum altitude of only 1,600 km (1,000 miles) and logged only 12,000 km (7,500 miles).

The launch of Pioneer III on December 6, 1958 was practically a rerun of mission Pioneer I:  A successful rocket launch, followed by the failure of the probe to achieve escape velocity. Pioneer III attained a maximum altitude nearly identical to that of Pioneer I:  102,300 km (63,580 miles).  Thankfully, like Pioneer I, Pioneer III made a significant discovery that kept the mission from being a complete flop.  Specifically, it discovered that the Van Allen radiation belts consist of at least two separate bands.

Total success came with the launch of Pioneer IV.  It broke free of the Earth's gravitational field and came to within 59,500 km (37,000 miles) of the Moon.  After completing its flyby of the Moon, Pioneer IV continued on and eventually settled into orbit around the Sun.  Before radio contact was lost, the craft had logged 654,252 km (406,620 miles).  By achieving escape velocity and flying close to another world (the Moon), Pioneer IV became America’s first successful deep-space probe.

I will relate the details of later missions in the Pioneer series in future editions of Flash’s Astronomical Facts.

 Sources:  The Aeronautics and Astronautics Chronology site at http://www.hq,nasa.gov, the History of Space Exploration site at http://www.astro.keele.ac.uk, the Space FAQs site at http://www.landfield.com, and Time Almanac 2000
 

For the week beginning February 24, 2002

Flash’s Astronomical Fact #123

In the previous edition of Flash’s Astronomical Facts, I noted that the current opposition of Saturn is a close one.  This is due to the fact that the planet is nearing its closest orbital approach to the Sun, called perihelion.

But there is more.

As it happens, the current orbital geometry is such that the planet Saturn appears fairly high in the Earth’s Northern Hemisphere night sky.

Would it make difference if it were low in the sky?

As a matter of fact… yes.

When you look at a celestial object that is directly overhead, you are looking at it along a straight line through the atmosphere.  But when you look at an object that is near the horizon, you are looking at it along an angle through the atmosphere.  In other words, the higher overhead an object is, the less the amount of atmosphere through which you must look to see it.  And since the atmosphere is in constant motion, it creates turbulence that distorts the light coming from that object.  Thus - all other things being equal - the higher overhead an object is, the clearer it will be.

So, here is a summary of what I have been saying for the last few editions of Flash’s Astronomical Facts.

The rings of Saturn are now tilted in the upward direction.  In fact, right about now, Saturn’s rings are about as wide open as they ever get.

Saturn’s current opposition is a close one.  In fact, right about now, Saturn is about as close to the Earth as it ever gets.

And, as I just got through saying, Saturn is high overhead for Northern Hemisphere observers.  In fact, right about now, Saturn is about as high overhead as it ever gets.

So what does it all mean?  What it means, dear visitor, is that if ever you needed a reason to dust off your backyard telescope, this is it.  The above combination of circumstances makes this an excellent time to view the planet Saturn.  In fact, right about now, conditions for viewing Saturn are about as good as they ever get; and will not again be this good until the year 2030!  You owe it to yourself to take at least one quick look. 

After sunset, look fairly high in the west for the constellation Taurus (The Bull).  In Taurus, you will see two bright star-like objects.  The one that is twinkling will be the star Aldebaran.  The one that is shining steadily will be the planet Saturn.

 Sources:  The Saturn site at http://www.spacedaily.com, the Saturn Perihelion site at http:///rimu.orcon.net.nz, andThe Old Farmers Almanac (2002 edition) and The World Almanac and Book of Facts 2002
 

For the week beginning February 17, 2002

Flash’s Astronomical Fact #122

In the previous edition of Flash’s Astronomical Facts, I noted that the rings of the planet Saturn are now tilted in the upward direction.  In fact, right about now, Saturn’s rings are about as wide open as they ever get.

But there is more.

As I noted in Flash’s Skywatcher’s Almanac, on December 3, 2001, Saturn attained an orbital position called opposition. That is, the Earth - in its smaller, faster orbit – came between the Sun and Saturn.  Saturn was thus positioned directly opposite the Sun as seen from the Earth (hence, opposition). 

Saturn comes into opposition about once every 54 weeks, as the Earth in its orbit goes around the Sun and once again “catches up” with the far planet Saturn in its larger, slower orbit.  Skywatchers always take note of when a planet is due to come into opposition, because when a planet is at opposition, it is also at or near its closest approach to the Earth; and also at or near its greatest brilliancy.

But not all oppositions are created equal.

The orbits of the planets are not perfect circles, but instead are slightly flattened circles called ellipses.  One consequence of an elliptical orbit is that a planet’s distance from the Sun is not the same at all points in its orbit.  At one point, the planet lies closest to the Sun.  This point is called perihelion.  At another point, the planet lies farthest from the Sun.  This point is called aphelion.

Obviously, an opposition occurring at perihelion affords much better telescopic viewing than one occurring at aphelion, as the planet is closer.  And yes, the difference can be quite substantial.  When Saturn is at perihelion, it is 1,352,000,000 km (840,400,000 miles) away from the Sun.   When Saturn is at aphelion, it is 1,514,000,000 km (941,100,000 miles) away from the Sun.  A difference of 162,000,000 km or over 100,000,000 miles!

When perihelion and opposition coincide, the planet is as close to the Earth as it ever gets.  And as it happens, Saturn is approaching perihelion, which will occur on July 25, 2003.  Thus, Saturn’s current opposition is a close one.  And next year’s opposition will be closer still. 

But there is still more – as I will explain in the next edition of Flash’s Astronomical Facts.

 Sources:  The Saturn site at http://www.spacedaily.com, the Saturn Perihelion site at http://rimu.orcon.net.nz, and The Old Farmers Almanac (2002 edition) and The World Almanac and Book of Facts 2002
 

For the week beginning February 10, 2002

Flash’s Astronomical Fact #121

As I stated in the previous edition of Flash’s Astronomical Facts, the planet Earth does not rotate on its axis bolt upright relative to its orbital plane.  Rather, it has an axial tilt – or rotational inclination, to use the scientific term – of some 23.45 degrees off of the vertical. 

Because the Earth tilts on its axis, its Northern and Southern Hemispheres alternately tilt towards and then away from the Sun over the course of the planet's one-year orbit.  As a result, the Earth undergoes seasonal changes - from spring to summer to autumn to winter.

But these seasonal changes are not unique to the Earth.  Because every other planet in the solar system tilts on its axis (to one degree or another), every other planet has seasons as well.

One example is the planet Saturn.  Saturn tilts on its axis some 26.73 degrees off of the vertical relative to its orbital plane, giving it a rotational inclination almost identical to the Earth’s.  Saturn’s Northern and Southern Hemispheres alternately tilt towards and then away from the Sun, just like the Earth's.  Therefore, Saturn undergoes a progression of seasons - from spring to summer to autumn to winter - just like the Earth.  The only significant difference is that Saturn requires 29.46 Earth years to complete one orbit of the Sun.  Therefore, whereas Earth seasons last only three months, Saturnian seasons last a little over seven years.

In the case of Saturn, however, more than just the planet itself tilts.

Saturn’s majestic rings stand above that planet’s equator.  This means that when the planet tilts, the rings seem to tilt with it.  During Saturn’s Northern Hemisphere summer, the planet’s Northern Hemisphere tilts towards the Sun, and observers on Earth see the ring system tilted in the downward direction.  This is generally considered to be the most aesthetically pleasing position, at least in the opinion of textbook illustrators.

A little over seven years later (or earlier), Saturn’s Northern Hemisphere experiences autumn (or spring), and the planet faces the Sun squarely.  The rings at those times have no tilt at all, and are seen edge-on.  This causes the rings – that are very thin relative to their breadth – to all but disappear completely from view.

Currently, Saturn’s Northern Hemisphere is experiencing winter, which means that the planet’s Northern Hemisphere is tilting away from the Sun.  This means in turn that the rings are now tilting in the upward direction.  In fact, right about now, Saturn’s rings are about as fully open in the upward direction as they ever get. This may not seem significant, but as a consequence of the position of its reflective rings, Saturn currently is the fourth brightest star-like object in the night sky, outshined only by Venus, Jupiter, and Sirius (The Dog Star).

I will have more to say about Saturn in the next edition of Flash’s Astronomical Facts.

 Sources:  The Saturn site at http://www.spacedaily.com and The Old Farmers Almanac (2002 edition) and The World Almanac and Book of Facts 2002
 

For the week beginning February 3, 2002

Flash’s Astronomical Fact #120

In the previous edition of Flash’s Astronomical Facts, I noted that the Earth does not spin on its axis (the imaginary line running between the Earth’s north and south geographic poles) bolt upright relative to the Earth’s orbital plane.  Rather, the Earth’s axis tilts 23.45 degrees off of the vertical. 

Currently, the Earth’s north pole points almost directly towards the star Polaris in the constellation Ursa Minor (The Lesser Bear).  And this orientation does not change as the Earth orbits the Sun.  No matter where the Earth is in its orbit, its north pole points towards Polaris.

It is the Earth’s tilt on its axis that is responsible for the change of seasons.  In the month of June, the Earth’s Northern Hemisphere tilts towards the Sun, while the Southern Hemisphere tilts away from the Sun.  This results in the Northern Hemisphere receiving the Sun’s rays directly, while the Southern Hemisphere receives the Sun’s rays at an angle.  This makes the Northern Hemisphere warmer than the Southern Hemisphere.  Thus, in June, the Northern Hemisphere experiences summer, while the Southern Hemisphere experiences winter.

Six months hence, in December, the Earth is on the opposite side of its orbit, but its north pole is still pointing towards Polaris.  Now, the seasonal situation is reversed.  Now, it is the Earth’s Northern Hemisphere that tilts away from the Sun, while the Southern Hemisphere tilts towards the Sun.  Now, it is the Northern Hemisphere that is receiving the Sun’s rays at an angle, while the Southern Hemisphere receives the Sun’s rays directly.  Now, it is the Southern Hemisphere that is warmer than the Northern Hemisphere.  Thus, in December, the Southern Hemisphere experiences summer, while the Northern Hemisphere experiences winter.

In between those extremes, the Earth in its orbit (still pointing towards Polaris, mind you) presents both its Northern and Southern Hemispheres to the Sun squarely.  Thus, both Hemispheres receive the Sun’s rays equally, and mild weather comes to both Hemispheres.  In March, the Northern Hemisphere experiences spring, while the Southern Hemisphere experiences fall.  In September, the situation is reversed.  The Northern Hemisphere experiences fall, while the Southern Hemisphere experiences spring.

The tilting of the Earth on its axis – properly known as rotational inclination – is not unique to our world.  Every planet in the solar system has some degree of rotational inclination.  In future editions of Flash’s Astronomical Facts, we will examine the axial tilts of some of the other planets in our solar system – some of which produce interesting effects in their own right.

 Sources:  Time Almanac 2002 and The World Almanac and Book of Facts 2002
 

For the week beginning January 27, 2002

Flash’s Astronomical Fact #119

A year is the amount of time that it takes for the Earth to complete one revolution of the Sun.  The path that the Earth takes in going around the Sun is called its orbit.  The plane defined by a planet’s revolutionary path is called its orbital plane.  The Earth’s orbital plane is given a special name: The ecliptic.

At the same time that the Earth is orbiting the Sun, it also is spinning on its axis, an imaginary line running through the Earth’s north and south geographic poles.  A day is the amount of time that it takes for the Earth to complete one rotation on its axis.

As the Earth spins on its axis, it does not do so while standing bolt upright relative to the ecliptic.  Instead, the axis of the Earth is tilted some 23.45 degrees off of the vertical.  A planet’s axial tilt is called its rotational inclination.

It is the Earth’s tilt on its axis that is responsible for the seasons - as I will explain in the next edition of Flash’s Astronomical Facts.

 Sources:  The World Almanac and Book of Facts 2002 and Webster’s New World Dictionary
 

For the week beginning January 20, 2002

Flash’s Astronomical Fact #118

In the previous edition of Flash’s Astronomical Facts, we discussed the concept of the light-year:  A unit of measure defined as the distance that light travels in one year.  A light-year is equal to about 9,460,800,000,000 km (5,865,700,000,000 miles).

Smaller distances also can be defined by the speed of light, simply by using shorter units of time.

One such measure is the light-second:  The distance light travels in one second.  A photon of light travels about 300,000 km (186,000 miles) per second. 

The mean distance from the Earth to the Moon is about 384,318 km (238,855 miles).  Thus, it would take a photon of light about 1.28 seconds to travel from the Earth to the Moon. The distance from the Earth to the Moon may therefore be expressed as 1.28 light-seconds.

There is also the light-minute:  The distance light travels in one minute.  A light-minute is 60 times greater than a light-second.  A photon of light travels about 18,000,000 km (11,160,000 miles) in one minute.

The mean distance from the Earth to the Sun is about 150,000,000 km (93,000,000 miles).  Thus, the Sun is about 8.33 light-minutes from the Earth.  Expressed another way:  If the Sun were to stop shining now, the people of the Earth would not become aware of it until another eight minutes and twenty seconds had passed.

Then, there is the light-hour:  The distance light travels in one hour.  A light-hour is 60 times greater than a light-minute.  A photon of light travels about 1,080,000,000 km (669,600,000 miles) in one hour.

The mean distance from the Sun to the outermost planet, Pluto, is 5,873,000,000 km (3,649,000,000 miles).  Or, about 5.44 light-hours.

The terms light-week and light-month are almost never used, partly because of the possibility of confusion.  That is to say, is a light-week based on a calendar week or a working week?  Is a light-month based on a 30-day month or a 31-day month?  Besides, such distances are a substantial percentage of a light-year, and are better expressed that way.  A light-month would be about 0.083 of a light-year; a light-week, about 0.019 of a light-year.

 Sources:  The Light Measurement sites at http://www.howstuffworks.com, http://www.glyphweb.com, and http://www.cyburban.com and Time Almanac 2002
 

For the week beginning January 13, 2002

Flash’s Astronomical Fact #117

Using terrestrial units of measure (such as kilometers or miles) to express the vast distances between the stars results in numbers so large as to be almost beyond comprehension.  The distance to the nearest star system visible to the unaided eye (Alpha Centauri A/B) is about 41,154,000,000,000 km (25,516,000,000,000 miles).  Even if expressed in scientific notation, these numbers are simply too big and too cumbersome to handle.  And mind you, this is the distance to just the nearest visible star system.

Obviously, to give meaning to the tremendous distances between the stars (as well as to the enormous sizes of certain heavenly bodies), astronomers need a unit of measure that is truly celestial in scale.  Their unit of choice is the light-year.

Despite what you might infer from the presence in the term of the word "year", a light-year is in fact a measure of distance and not of time.  A light-year is the distance that a photon of light, moving at 300,000 km (186,000 miles) per second, travels in one year; specifically, one sidereal year of 365 days, 6 hours, 9 minutes, and 9.54 seconds mean solar time.  This works out to about 9,460,800,000,000 km (5,865,700,000,000 miles).  Thus, the distance to Alpha Centauri A/B may be expressed as 4.35 light-years.  Stated another way:  A photon of light from Alpha Centauri arriving at Earth today left that star system 4.35 years ago.

Here are some distances and sizes – expressed in light-years - of some of the better-known heavenly bodies.  The distance to the brightest star in Earth’s night sky (Sirius) is about 8.7 light-years.  Our home galaxy (The Milky Way Galaxy) is at least 100,000 light-years in diameter.  The distance to the farthest object visible to the unaided eye (The Andromeda Galaxy) is about 2,900,000 light-years.

As an exercise, dear visitor, you do the math and convert the figures in the above paragraph from light-years to kilometers and from light-years to miles.  By doing so, you will see quickly enough why astronomers prefer using light-years!

I will have more to say on this subject in the next edition of Flash's Astronomical Facts.

 Sources:  The Light-Year sites at http://www.howstuffworks.com and http://www.encyclopedia.com, the Alpha Centauri site at http://home.sunrise.ch, the Sirius site at http://antwrp.gsfc.nasa.gov, and the Milky Way Galaxy and Andromeda Galaxy site at http://seds.lpl.arizona.edu
 

For the week beginning January 6, 2002

Flash’s Astronomical Fact #116

In the previous edition of Flash’s Astronomical Facts, I noted that the Earth’s atmosphere is divided into four distinct layers according to how the temperature of the air molecules within those regions varies.  We then examined the two lowermost layers – the troposphere and the stratosphere – in detail.  In this edition, we will examine in detail the two uppermost layers.

The next layer out from the stratosphere extends from about 50 km (30 miles) to about 80 km (50 miles).  It is called the mesosphere, or “middle sphere”.  The temperature of the air molecules within this region once again decrease with altitude, dropping from about 0 degrees C at the lower reaches to about -100 degrees C at the upper reaches.  The air in the mesosphere is thinner than in the stratosphere (although, it should be noted, most meteors burn up in the mesosphere).

The next layer extends from about 80 km (50 miles) to about 600 km (360 miles).  It is called the thermosphere, or “hot sphere”.  It is aptly named, for the temperature of the air molecules once again begins to increase with altitude, rising from about -100 degrees C at the lower reaches to about 1000 - 1500 degrees C at the upper reaches.  The air is thinner than in the mesosphere, but what few atoms are present become heated to extreme temperatures as a consequence of absorbing high-energy radiation (chiefly gamma rays and X-rays) from outer space.  It should be noted that although the individual atoms are extremely hot, the air is so diffuse that there is not much in the way of total heat.

The thermosphere may be divided into two sub-layers.  The lower thermosphere sometimes is called the ionosphere or “sphere of ions” and extends from about 80 km (50 miles) to about 400 km (250 miles).  In this layer, electrons are knocked off of atoms by cosmic radiation bombardment and exist only in the form of ions.  Several subdivisions within the ionosphere  – called the D layer, E layer, and F layer - reflect select frequencies of radio waves.  The layers act something like mirrors, sending radio signals from the ground back towards the planet's surface where they can be heard beyond the horizon.

The upper thermosphere sometimes is called the exosphere or “outer sphere”.  It extends from about 400 km (250 miles) to about 600 km (360 miles).  At the upper reaches of the exosphere, the chemical composition of the atmosphere becomes indistinguishable from the chemical composition of outer space.  At that point, the Earth’s atmosphere may be said to have reached its maximum height.

Beyond the exosphere lies true outer space.

 Sources:  The Earth’s Atmosphere sites at http://newmedia.avs.uakron.edu, http://www.doc.mmu.ac.uk, http://www.jccc.net, and http://www.miami.ci.org
 

For the week beginning December 30, 2001

Flash’s Astronomical Fact #115

The envelope of air that surrounds the Earth is called the atmosphere.  The atmosphere retains and distributes heat, provides life-giving oxygen, and in other ways helps make possible life on our planet. 

But the atmosphere does not have the same composition throughout.  Its physical and chemical characteristics vary with altitude.

Scientists divide the Earth’s atmosphere into four distinct layers according to how the temperature of the air molecules within those regions varies.  How high above the Earth’s surface each layer begins varies with latitude or the overall temperature of the atmosphere.

The bottommost layer of the atmosphere is called the troposphere or “turning sphere”.  The troposphere extends from the Earth’s surface up to an average altitude of about 12 km (8 miles).  Note that I said average altitude.  As I stated above, the height of each atmospheric layer varies with latitude.  Over the poles, the troposphere extends up to about 8 km (5 miles); over the equator, up to about 16 km (10 miles). 

Within the troposphere, temperature decreases fairly steadily with altitude, beginning at an average of 15 degrees C (59 degrees F) at the planet’s surface and then dropping by about 6.5 degrees C for every 1 km elevation.  At the upper reaches of the troposphere, temperatures can drop to as low as –50 degrees C.

About 75% percent of the air molecules in the entire atmosphere are found within the troposphere.  The air within this layer is relatively dense and water vapor is plentiful; hence, almost all weather phenomena occur within the troposphere.  Indeed, the highest of the true clouds are found at the upper reaches of the troposphere.

The next layer outwards is called the stratosphere or “covering sphere”.  The stratosphere extends from an average of about 12 km (8 miles) to about 50 km (30 miles) above the Earth’s surface. The temperature of the air molecules within the stratosphere actually increases with altitude, from about –50 degrees C at the lower reaches to about 0 degrees C at the upper reaches.  This is due to the presence in the stratosphere of ozone, which absorbs high-energy ultraviolet radiation from the Sun. 

Within the stratosphere, air is more diffuse and water vapor is virtually non-existent.  As a consequence, there are no true clouds within the stratosphere.  Stratospheric winds tend to be strong, steady, and horizontal.  Jet planes, therefore, travel through this region whenever possible as it means increased fuel economy and a smoother ride. 

We will examine the two remaining atmospheric layers in the next edition of Flash’s Astronomical Facts.

 Sources:  The Earth’s Atmosphere sites at http://newmedia.avs.uakron.edu, http://www.doc.mmu.ac.uk, http://www.jccc.net, and http://www.miami.ci.org
 

For the week beginning December 23, 2001

Flash’s Astronomical Fact #114

The passing of the old year and the beginning of the new will be heralded by a number of spectacular celestial events, which I will describe in detail below.  Be sure to mark the following dates on your calendar:

December 28, 2001:  Saturn and the Moon will come into conjunction.  Conjunction is the astronomical term for when two celestial bodies reach the same celestial longitude.  During most such Moon/planet conjunctions, the Moon passes either above or below the planet.  But in the early morning hours of December 28, 2001, skywatchers in most of the continental United States will get a rare treat, as the Moon will pass directly in front of Saturn, concealing it from view.  Such an event is called an occultation.  Consult your local newspaper for the exact time when this event will occur in your area.

December 30, 2001:  Not only are we going to have a Full Moon, we are going to have a lunar eclipse.  Unfortunately, the Moon rides high this night, so our satellite world will not enter the darker, central portion of the Earth’s shadow (called the umbra).  Instead, it will enter only the lighter, outer portion of the Earth’s shadow (called the penumbra).  Hence, this eclipse will be what is called a penumbral eclipse.  Though it will not be as spectacular as a total lunar eclipse or even a partial lunar eclipse, it still will be worth watching.  The Moon will take on a dull reddish-brown color as it enters the penumbra.  The eclipse will be visible from start to finish, from Hawaii to across North America (except for the east coast, which will not see the end of the eclipse).

January 1, 2002:  The planet Jupiter will come into opposition during the very early morning hours of New Year’s Day.  Opposition is the astronomical term for when an inner planet  passes directly between the Sun and an outer planet.  In this case, Jupiter will be positioned directly opposite the Sun as seen from the Earth (hence, opposition).  When a planet is at opposition, it rises in the east at sunset, stays out all night, and sets in the west at sunrise.  Moreover, a planet at opposition is also at or near its closest approach to the Earth, as well as being at or near its greatest brilliancy.  Indeed, Jupiter will be brightest for the entire calendar year of 2002 just one hour into the New Year.  As if that were not enough, the planets Saturn and Mars will join Jupiter during the early evening hours of December 31, 2001.

What a way to say goodbye to the old year – and welcome the new.

 Sources:  The Saturn Occultation site at http://www.lunar-occultation.com and The Old Farmer’s Almanac (2001 and 2002 editions), Time Almanac 2001, and The World Almanac and Book of Facts 2002
 

For the week beginning December 16, 2001

Flash’s Astronomical Fact #113

With Christmas coming up in just a few days, this week’s edition of Flash’s Astronomical Facts will relate how the stars gave birth to a popular yuletide practice:  The placement of decorative lights on Christmas trees. 

We begin with the origin of the Christmas tree itself. 

In Europe, the evergreen tree has been used as a pagan symbol of the winter season since at least the 8th century.  Evergreen trees are aptly named because they remain ever green - even during the winter, when all other flora either are entering a period of dormancy or dying from the freezing cold.  Small wonder then that the evergreen tree came to represent also eternal life.  And eternal life in the hereafter is the reward promised to those who accept Jesus Christ as their savior.  As you can see, it all fits together.

Okay, so much for the tree.  But what about the lights?

A famous legend explains how people came to decorate their Christmas trees with lights.  The story goes that Martin Luther, the 16th century Protestant reformer, was walking home one clear winter night when he came upon an evergreen tree.  The stars in the background appeared to be attached to the edges of the tree. It created such a beautiful sight that Martin Luther wanted to replicate it.  Using some lengths of wire, he attached a number of candles to the branches of his home evergreen tree.  When he lit the candles, his tree looked like the tree he saw on his way home.

Unfortunately, there exist no historical records that substantiate that the above incident ever took place. The tale, however delightful, is almost certainly apocryphal. 

But regardless of the veracity of the legend, having an evergreen tree in the house during the Christmas season was a firmly established custom in Germany by the 1600s, although lighting the tree with candles was not a common practice until the 1700s.

Nowadays, Christmas trees are lighted by means of strings of electric light bulbs.  Not only is this far safer, the light from the electric bulbs more closely resembles the starlight that Martin Luther is supposed to have seen.

 Sources:  The Christmas Tree sites at http://www.happywomanmag.com and http://www.ultranet.com
 

For the week beginning December 9, 2001

Flash’s Astronomical Fact #112

What follows is the fourth of an occasional series about the constellations.  It is being presented in two parts, of which this is the second.

In the previous edition of Flash’s Astronomical Facts, we examined the constellations Corona Borealis (The Northern Crown) and Corona Australis (The Southern Crown).  Though both constellations are small, they are noteworthy in that the principal stars of each form patterns that are remarkably similar to each other in both size and shape.

Each of these constellations has some mythology associated with it.  Unfortunately, as a consequence of the stories being handed down largely by word of mouth, some of the details have become muddled.  Keep that caveat in mind as I relate the legends of the celestial crowns.

The myths regarding Corona Australis are neither very long nor very interesting, so let us get the Southern Crown out of the way first.  In classical mythology, Corona Australis originally was the crown of Seleme, the mother of the Greek god Dionysus.  Dionysus placed Seleme’s crown in the heavens in her honor.  But another legend suggests that the Southern Crown fell off of the head of Sagittarius (The Archer), its neighboring constellation.

The mythology of the Northern Crown is much more interesting - and much more epical.

Corona Borealis played a minor role in one of the greatest stories in classical mythology:  Theseus’ battle with the Minotaur. 

The Minotaur, a ferocious beast that was half man and half bull, was confined on the island of Crete within the Labyrinth - a maze so huge, so complex, and so baffling, that no one who entered it could ever find his way back. 

For reasons too complicated to relate in this essay, the city of Athens was obligated to pay tribute to King Minos of Crete every ninth year.  The tribute took the form of seven Athenian youths and seven Athenian maidens.  These unfortunate souls were forced to enter the Labyrinth, where they soon were eaten by the Minotaur.

When the time came for the next group of young people to be rounded up for tribute, a gallant youth named Theseus volunteered to be one of the sacrifices.  Some thought he was just being noble; in actuality, he had a plan to kill the Minotaur and put an end to King Minos' barbaric tribute.

Time out for an aside:  Theseus' ancestry is one of those "muddled details" I mentioned.  In most versions of the story, Theseus is the son of King Aegeus of Athens.  In this version - which includes the origin of Corona Borealis - Theseus is the son of Poseidon, the god of the sea.

Upon arriving in Crete, Theseus proclaimed himself to be the son of Poseidon and demanded an audience with King Minos.  Theseus and Minos made a wager of sorts.  If Theseus could kill the Minotaur barehanded, then Athens' obligation to pay tribute to Minos would be rendered null and void.  In addition, Theseus wished to be the first to enter the Labyrinth, so as to spare the other sacrifices.

Minos agreed to Theseus’ terms – on the condition that the youth first prove that he was indeed the son of Poseidon.  Minos threw his gold ring into the sea and challenged Theseus to find it and bring it back - a task that should be simple enough for someone claiming to have been fathered by the god of the sea. 

With the help of the Nereids (sea nymphs), Theseus not only recovered Minos’ ring, but also was given (either by the Nereid Thetis or the sea queen Amphitrite, accounts differ) a crown fashioned by Hephaestus, the god of the forge.  The crown was a masterful work, a half-circle of gold rosettes adorned with jewels.

When Theseus brought back the crown in addition to the ring, King Minos needed no further convincing of the veracity of Theseus’ claim.  The heroic youth would indeed be the first to enter the Labyrinth.

But while Theseus was confident that he could defeat the Minotaur mano-a-mano, he was less than sure of his ability to find his way back out of the Labyrinth.  That was when Ariadne, the daughter of King Minos, came to Theseus’ aid.  In exchange for the young man’s promise of marriage, Ariadne provided Theseus with a means by which to escape from the Labyrinth:  A ball of magic string. 

Theseus placed the ball of magic string down on the ground near the entrance to the Labyrinth.  The ball unrolled itself, leading Theseus straight to the Minotaur.  After wrestling the creature to the ground and beating it to death with his fists, Theseus escaped the Labyrinth simply by following the string back out the way he came.

King Minos honored his wager with Theseus.  The city of Athens was released from its obligation to send tribute to Minos.  Minos then gave Hephaestus’ crown to Theseus and Ariadne as a wedding present.

But the wedding was never to take place.  The couple set sail for Greece so that Theseus could present his fiancée - now wearing Hephaestus’ crown - to his family.  En route, Ariadne came down with the worst case of mal de mer in history and had to go ashore on the island of Naxos.  From this point forward, accounts differ as to the final fate of Ariadne.

One version states that a violent gust of wind sent the ship far away, stranding Ariadne on the island.  By the time Theseus was able to get back to Naxos, Ariadne had died. The goddess Aphrodite then placed Hephaestus’ crown in the heavens, where, as Corona Borealis, it would serve as an eternal tribute to a marriage that might have been.

Another version suggests that Theseus took the opportunity to abandon Ariadne on the island because she had dared to extract from him a promise of marriage.  Ariadne appealed to the supreme Greek god, Zeus, who dispatched the god Dionysus to comfort her.  Dionysus fell in love with Ariadne.  They married and had four children.  When Ariadne died, Dionysus placed Hephaestus’ crown in the heavens where, as Corona Borealis, it would honor his mortal wife throughout eternity.

Yet another version states that Dionysus already had eyes for Ariadne.  To get his rival out of the way, Dionysus gave Theseus a case of amnesia.  This resulted in Theseus sailing off without his betrothed out of forgetfulness rather than malice.  When Dionysus presented himself to Ariadne, he told her that he was a god.  She challenged him to prove his claim.  So saying, Dionysus threw Hephaestus’ crown skywards.  The jewels became stars and Corona Borealis was born.  Apparently, that was proof enough.  Ariadne accepted Dionysus’ proposal of marriage. 

Other ancient cultures developed their own mythologies about the celestial crowns.  One delightful story from North American Indian lore explains the opening in the circle of the Northern Crown this way:  Originally, Corona Borealis was a full circle, each of its stars being a beautiful fire maiden dancing in the night sky.  The gap occurred when one of the fire maidens became smitten with a handsome male warrior down here on Earth.  That fire maiden left the troupe and descended to Earth to be with him, thus leaving a hole in the choreography.  In essence, she gave up show biz for true love.

 Sources:  The Corona Borealis and Corona Australis sites at http://www.mtsn.tn.it, http://www.dibonsmith.com, 
http://einstein.stcloudstate.edu, http://chandra,harvard.edu, http://seds.lpl.arizona.edu, and Mythology by Edith Hamilton
 

For the week beginning December 2, 2001

Flash’s Astronomical Fact #111

What follows is the fourth of an occasional series about the constellations.  It is being presented in two parts, of which this is the first. 

There are eighty-eight officially recognized constellations in the heavens.  The constellations come in a variety of shapes, depicting animals (both real and fanciful), inanimate objects, and the gods and heroes of classical mythology.  Some constellations are huge, covering vast areas of the night sky.  Others are small, taking up little more than a tiny patch of the fabric of space.

One thing that can be said of the constellations is that - like snowflakes - there are no two exactly alike.

But two constellations put that assertion to the test.  The constellations to which I am referring are Corona Borealis (The Northern Crown) and Corona Australis (The Southern Crown).  Not only are these two constellations similar in both size and shape, they are depicted as representing similar objects!

The brightest stars in each constellation form an incomplete circle, suggesting not a coronet as might have been worn by a European monarch, but rather a half-wreath of laurel leaves as might have been worn by a Roman emperor.

Corona Borealis is a small northern hemisphere constellation located between the large constellations Hercules (The Strongman) and Bootes (The Herdsman).  Comparably small Corona Australis, a southern hemisphere constellation, likewise is sandwiched between two large constellations - in this case Sagittarius (The Archer) and Scorpius (The Scorpion).

Both Corona Borealis and Corona Australis have some mythology associated with them.  But we will examine that aspect of the two crowns in the next edition of Flash’s Astronomical Facts.

 Sources:  The Corona Borealis and Corona Australis sites at http://www.mtsn.tn.it
 

For the week beginning November 25, 2001

Flash’s Astronomical Fact #110

The planet Earth seems to spin on its axis exactly once every twenty-four hours, as steady as clockwork.  In actuality, the clockwork is not all that steady.  The rotation of the Earth varies slightly in the following ways:

Tidal friction is slowing down continuously the Earth’s rotation.  This variation increases the length of the day by about one millisecond per century.  Because this effect has been going on since the formation of our planet, scientists refer to this effect as secular variation.

For reasons not entirely clear, the speed of the Earth’s rotation may increase for a period of, say, five to ten years, then decrease for a similar period.  This effect has increased the length of the day by about forty-four seconds since the year 1900.  The cause of this effect is, as I said, not well understood; but scientists believe that it may be the result of motions within the Earth’s molten interior.  Scientists refer to this effect as irregular variation.

There are two other rotational variations: One of them has a period of six months, the other has a period of one year.  The cumulative effect of these variations is such that each year, the rotation of the Earth falls thirty milliseconds behind on or about June 1, then moves thirty milliseconds ahead on or about October 1.  The annual variation may be caused by the change in wind patterns in both the northern and southern hemispheres.  The semi-annual variation is due mainly to the gravity of the Sun, which produces tidal forces that distort slightly the Earth’s shape.  Because these changes come and go with the seasons, scientists refer to these effects as periodic variations.

The secular and irregular variations were discovered by comparing the rotation of the Earth to the orbital motion of the Moon around the Earth and the planets around the Sun.  The periodic variations were discovered with the help of quartz crystal clocks.  The introduction in 1955 of the cesium atomic clock made possible even more accurate measurements of the irregular and periodic variations.

 Source:  The World Almanac and Book of Facts 2002
 

For the week beginning November 18, 2001

Flash’s Astronomical Fact #109

As noted in last week’s edition of Flash’s Skywatcher’s Almanac, yesterday - November 17, 2001 - was the first day of Ramadan, the holiest month on the Islamic calendar.  During Ramadan, Muslims fast during the daylight hours.

The Islamic calendar is a strictly lunar calendar.  And when I say strictly lunar, I mean STRICTLY lunar.  When the thinnest sliver of a waxing crescent Moon makes its appearance in the sky, a new month begins.

As a consequence of this strict adherence to lunar cycles for religious purposes, the first day of Ramadan comes ten to eleven days earlier than it did the year before.  In 2000, the first day of Ramadan occurred on November 27.  In 2002, the first day of Ramadan will occur on November 6.

 Sources:  The Old Farmer’s Almanac (2000, 2001, and 2002 editions), and The World Almanac and Book of Facts 2002
 

For the week beginning November 11, 2001

Flash’s Astronomical Fact #108

What follows is the fourth of an occasional series about flags with stars.  This entry in the series will be presented in two parts, of which this is the second.

In the previous edition of Flash’s Astronomical Facts, we examined the flag of the State of Arizona.  I finished the essay by noting that the origin of the Arizona flag has been the subject of historical confusion since day one.

In order for you to understand the point of confusion, I must first give you this timeline of events:

February 14, 1912 – Arizona admitted to the Union as the 48th state.
March 16, 1914 – Keel laid for the battleship U.S.S. Arizona.
June 19, 1915 – U.S.S. Arizona launched.
October 17, 1916 - U.S.S. Arizona commissioned.
February 17, 1917 – Arizona State Legislature officially adopts state flag.

Now, to answer your questions:  Yes, the U.S.S. Arizona mentioned in the timeline is indeed the same U.S.S. Arizona that was sunk during the attack on Pearl Harbor.  It was the second battleship to bear the name.

And yes, the timeline is correct.  Between the time that the State of Arizona was granted statehood and the time that its legislature officially adopted a state flag, the United States government started – and completed – construction on the U.S.S. Arizona.

This coincidental timing created a sort of “chicken-or-the-egg” question as it pertains to the origin of the Arizona flag.  Specifically, did the State of Arizona adopt an official state flag, and then present said flag to its namesake battleship?  Or, was the Arizona state flag adopted from a ship’s flag that flew first over the U.S.S. Arizona?  That is the point of historical confusion.

I herewith present the resolution to the confusion.  Charles W. Harris, then Adjutant General of the Territory of Arizona, designed the flag in 1911 - a year before Arizona became a state and three years before construction began on the U.S.S. Arizona.  In other words, it was the state that presented its flag to the battleship, not the other way around.

And just why did it take so long for the State of Arizona to adopt an official state flag?  Priorities, that's why.  Arizona’s political leaders first had to secure statehood for Arizona.  Next, they had to see to it that Arizona’s transition from a territory to a state was a smooth one.  Matters of lesser importance - such as designing and adopting a state flag – were “put on the back burner”.

Eventually, the Arizona State Legislature got around to considering the matter; and, according to history, debate over the flag became quite heated, as Harris' design was not universally liked.  In fact, the governor of Arizona so hated the design that he refused to sign the bill making it the official state flag (the bill became law without his signature, and the flag was adopted). 

Interestingly enough, some of the points of debate were on matters of astronomy.  Some members of the legislature considered rays of sunlight coming off of a star to be “astronomically improbable”.

 Sources:  The Arizona State Flag sites at http://www.ace.unsw.edu.au and http://www.netstate.com
 

For the week beginning November 4, 2001

Flash’s Astronomical Fact #107

What follows is the fourth of an occasional series about flags with stars.  This entry in the series will be presented in two parts, of which this is the first.

The flag of the State of Arizona has one of the boldest designs of any flag in the world.  And as it happens, the flag features not one, but two, design elements of an astronomical nature.

Officially, the flag of the State of Arizona has a hoist (height) of four feet and a fly (length) of six feet.  The banner is divided lengthwise into two horizontal sections of equal area.

The bottom half of the flag is intended to represent a lake.  So naturally, it is solid blue in color.

The upper half of the flag is intended to represent the Arizona sky at sunset.  To achieve this effect, twelve lines extend up and away in a radial pattern from the exact center of the flag to the edges of the upper section.  The twelve lines thus divide the upper section into thirteen projecting rays.  The projecting rays are colored red and yellow (seven red rays alternating with six yellow).

Superimposed over all is a large star in the exact center of the flag.  The star is in the shape of a regular pentagram and oriented so that one point faces upwards.  The star's height is equal to one-half of the hoist.  Thus, on the official four foot by six foot flag, the star's highest point lies one foot from the top edge of the banner, while the two lowest points each lie one foot from the bottom edge.  The star is copper in color, symbolic of Arizona’s vast copper resources.  The copper star rises as the Sun behind it sets.

The flag of the State of Arizona pays homage to the flag of the United States of America in several ways.  First, the large star in the center of the Arizona flag is, as I said, in the shape of a regular pentagram, with one point facing upwards - exactly the same shape and orientation as the stars on the American flag.  Second, the red and blue colors on the Arizona flag are exactly the same shade as those on the U.S. flag.  Finally, the stylized sunset in the upper section of the Arizona flag sports the same number of projecting rays as there are stripes on the American flag - thirteen.

The flag of the State of Arizona has more than just an interesting design.  It has also an interesting origin. An origin that causes historical confusion to this very day.  But we will examine that aspect of the Arizona flag in the next edition of Flash's Astronomical Facts.

 Sources:  The Arizona State Flag sites at http://www.ace.unsw.edu.au and http://www.netstate.com
 

For the week beginning October 28, 2001

Flash’s Astronomical Fact #106

Halloween comes up this Wednesday, October 31, 2001.  As it happens, most of the continental United States will see the Moon achieve Full Moon status in the mid-to-late evening hours of October 31.  Thus, on Halloween, the lunar disc will rise in the east at sunset, stay out all night long, and set in the west at sunrise.

At this time of year, certain astronomical and meteorological conditions combine to make the Full Moon of October look orange as it rises, almost like a giant pumpkin popping up over the eastern horizon.  When such occurs on October 31 (as it will this year), it just makes an already creepy night seem creepier still.

The Halloween Full Moon provides an opportunity to explain a few things about the timing of celestial events.

Whenever an astronomical event is due to occur at a specific hour and minute, that time is posted in Flash’s Skywatcher’s Almanac as Eastern Standard Time (or Eastern Daylight Time, as appropriate).  This is done to conform with the system used in The Old Farmer’s Almanac, the principal source of astronomical data for Flash’s Skywatcher’s Almanac.

When the Moon reaches the point (and I emphasize the word point) in its orbit where the Earth lies exactly between it and the Sun, it has achieved a special orbital position called Full Moon.  It is called Full Moon because the half of the Moon facing the Earth is fully illuminated by the Sun.  Keep in mind that the Moon in its orbit is in continuous motion around the Earth.  Therefore, the instant (and I emphasize the word instant) that the Moon achieves the position of Full Moon, it then enters immediately its waning (shrinking) gibbous phase (for a more detailed examination of lunar phases, see Flash’s Astronomical Fact #29 (for May 7, 2000)).

And at what time on Earth will this instant of the Full Moon occur?  It all depends on your local time zone.  As noted in Flash’s Skywatcher’s Almanac, the Moon achieves fullness at exactly 12:41 a.m. Eastern Standard Time, on November 1, 2001.  This means that fullness will occur at 11:41 p.m. Central Standard Time, on October 31, 2001; 10:41 p.m. Mountain Standard Time, on October 31, 2001; and 9:41 p.m. Pacific Standard Time, on October 31, 2001.

Because each calendar day lasts from one midnight to the next, those Americans living in the Eastern Time Zone technically will not have a Full Moon on Halloween because the Moon will not achieve the position of Full Moon until the early morning hours of November 1.

However, humans instinctively distinguish nightime from daytime by the rising and setting of the Sun, not by some arbitrarily selected demarcation points.  Night is the period between sunset and sunrise.  Therefore, Americans living in the Eastern Time Zone will claim that they also will have a Full Moon on Halloween because the Full Moon will have occurred during Halloween night in some time zone on the Earth.  And no scientific technicalities are going to convince them otherwise.

But, on the other hand, does it really matter?  Even if the Moon does not technically achieve Full Moon on October 31 where you live, it certainly will look big and bright in the sky all throughout Halloween night.  So enjoy this All Hallow’s Eve – made spookier than usual due to the presence in the night sky of the Full Moon.

 Sources:  The Full Moon on Halloween sites at http://www.cnn.com and http://www.almanac.com, and the Full Moon Dates 1900 – 2100 site at http://home.hiwaay.net
 

For the week beginning October 21, 2001

Flash’s Astronomical Fact #105

What follows is the third of an occasional series about the constellations.  It is being presented in two parts, of which this is the second. 

In the previous edition of Flash’s Astronomical Facts, we examined the constellations Ursa Major (The Greater Bear) and Ursa Minor (The Lesser Bear). 

In their pictorial representations on star charts, each of the heavenly bears is depicted as having a long tail - much longer, in fact, than that of any earthly bear.  This oddity raises one of the most frequently asked questions in astronomy:  Why do terrestrial bears have short tails, while celestial bears have long tails?

The long tails are explained by a tall tale; specifically, a legend from Greek mythology.  But before I tell you the story, here is some background information that you need to know.  Although the gods and goddesses of classical mythology had virtually unlimited powers, they did operate under certain restrictions.  Among other things, one god could not cast a spell on another god of comparable or greater power; and one god could not reverse a spell cast by another god of comparable or greater power.

Keep the above information in mind while I relate the story of how the celestial bears came to have long tails.

In Greek mythology, Zeus was the supreme god and Hera was the supreme goddess.  Zeus and Hera reigned over Mt. Olympus as husband and wife.  They were a bit of an odd couple in that Hera was a staunch defender of marriage, while Zeus was forever on the prowl for lovely young maidens.  One day, he set his sights on a mortal beauty named Callisto.  From their relationship, a son - who later would be named Arcas - was conceived.

When Hera found out about the affair and the child that had resulted from it, she became livid with rage.  But since Hera and Zeus were power peers, she could not cast a spell on her cheating husband.  So Hera focused all of her wrath on Callisto.  Wishing to punish the mortal girl in the worst way possible, Hera transformed Callisto into a she-bear.  By this single action, Hera had separated Zeus from Callisto, Callisto from Arcas, and had turned the beautiful girl into an ugly beast.  Hera's revenge was most thorough indeed.

But Hera's action against Callisto, horrific as it was, did not bring a close to the matter as far as the supreme goddess was concerned.  Hera wished also to punish – again, in the worst way possible - the child born of the affair.  Hera waited patiently for Arcas to grow to young manhood and become a fairly proficient hunter. Hera then arranged for Callisto to appear before him.  Hera was hoping that Arcas, out of fear, would bring down the beast by means of his arrows.  In this way, when Hera revealed the bear's true identity to Arcas, the mortal youth would have to live forever with the knowledge that he had killed his own mother!

And that is exactly what happened – almost. Everything was going according to Hera’s fiendish plan when Zeus, having learned of his wife’s intentions, interceded at the last instant and moved Callisto out of the path of Arcas' arrow.

Concluding that enough was enough, Zeus decided that he would spare Callisto and Arcas from any more of Hera’s vengeful actions.  To accomplish this objective, he would bestow on mother and son the ultimate glory - placement in the heavens.  In this way, Callisto and Arcas would achieve immortality among the stars, where they would be honored by both gods and mortals throughout eternity.

Zeus could not reverse his wife’s spell and transform Callisto back into a woman, so he did the next best thing.  Zeus transformed Arcas into a small bear, thereby reuniting mother and son. Next, he tied together the short tails of each bear.  Zeus then swung the bears overhead, like an Argentine gaucho wielding his bola weapon.  When he had built up enough momentum, Zeus cast the bears into the heavens.

But Hera was still angry, this time at Zeus for having bestowed so high an honor on her romantic rival and the child born of that rivalry.  Hera did not wish for Callisto and Arcas to enjoy their new status in the stars, but she could not reverse Zeus’ decision to place the bears in the night sky.  So Hera appealed to Oceanus, the Titan of the Oceans, for help.  Though Oceanus likewise could not reverse Zeus’ decision, he would arrange things so that the new heavenly bears would never again touch the oceans of the Earth.  This he accomplished by positioning both bears near the north celestial pole.  So near in fact, that Polaris - the North Star - represents the end of Arcas’ tail. 

Thus, as the Earth rotates beneath them, Arcas (now Ursa Minor) seems to follow close behind his mother Callisto (now Ursa Major).  And because the constellations both lie so close to the north celestial pole, Ursa Major and Ursa Minor never touch the oceans.  Not from the perspective of an observer in the mid-to-high northern latitudes, anyway.

And that is the story.

Oh, did I forget to mention how the bears acquired their long tails?  I did, didn’t I?

Okay, here is the explanation:

Recall that Zeus swung the bears overhead in order to build up enough momentum to cast them into the heavens.  The action of swinging the bears by their tails caused said tails to become stretched.  And that is how the two celestial bears came to have long tails. 

Hey, I said it was an explanation.  I never said it was a good explanation.

 Sources:  The Constellations sites at http://seds.lpl.arizona.edu, and http://www.lincoln.k12.or.us, and Mythology by Edith Hamilton
 

For the week beginning October 14, 2001

Flash’s Astronomical Fact #104

What follows is the third of an occasional series about the constellations.  It is being presented in two parts, of which this is the first. 

When you look at a good-sized star chart, you will see more on the chart than just stars.  You will see also demarcation lines that divide the heavens into a number of separate and distinct regions, much the same way that county lines divide a state into a number of separate and distinct counties.  There are eighty-eight such bounded regions in the night sky, one for each of the eighty-eight officially recognized constellations.

Within each constellation’s bounded region lie a number of stars, both faint and bright.  And while the faint stars are just as much a part of the constellation as the bright stars, it is the bright stars – and simply because they are bright – that get all the attention.

When the ancients gazed at a constellation, they perceived its bright stars as defining a pattern – a pattern that suggested the shape of an animal, an object, or even a human.  As a result, the ancients pictured the constellations to be such things as fabulous animals, venerated objects, and the gods and heroes of classical mythology.

Stellar cartographers employ two different kinds of visual aids to help the person reading the star chart understand how the ancients could have perceived such patterns in the bright stars of a constellation.  First, as it is a constellation’s bright stars that define the pattern, stellar cartographers draw line segments between said bright stars.  The stars and lines together make a stick figure of sorts.  The stick figure enables the star chart reader to see what the ancients pictured in their minds.  Second, to enhance further the perception, a fanciful picture in outline form is drawn around the stick figure.

Ursa Major (The Greater Bear) and Ursa Minor (The Lesser Bear), two of the northern hemisphere’s most well known constellations, are handled in just that way.  By drawing line segments between the bright stars of Ursa Major, stellar cartographers produce a stick figure that shows how the ancients could have perceived that constellation as a large bear.  Likewise, line segments are drawn between the bright stars of Ursa Minor to show how the ancients could have perceived that constellation as a small bear.

However, when one looks at the fanciful pictures that surround the stick figures of Ursa Major and Ursa Minor, an oddity catches the eye.  The tails of both the Greater Bear and the Lesser Bear are long - much longer than those of any earthly bear.  This anomaly raises one of the most frequently asked questions in astronomy: Why do terrestrial bears have short tails, while celestial bears have long tails?

Are you curious, dear visitor?  Then, I will satisfy your curiosity by answering the question – beginning in the next edition of Flash’s Astronomical Facts.

  Source:  The Constellations site at http://seds.lpl.arizona.edu
 

For the week beginning October 7, 2001

Flash’s Astronomical Fact #103

In the previous edition of Flash’s Astronomical Facts, I enumerated some of Dr. Robert Hutchings Goddard’s many achievements in the field of rocketry.  With such a long string of accomplishments to his credit, the brilliant scientist should have enjoyed universal public acclaim during his lifetime.  Sadly, just the opposite was the case.  Both Goddard and his work were subjected to merciless ridicule in The New York Times and other prominent newspapers of his day.

The trouble started when Goddard published a 1920 report entitled “A Method of Reaching Extreme Altitudes”.  In his paper, Goddard asserted that rockets could achieve higher altitudes than balloons, and therefore would be superior to balloons for carrying aloft scientific instrument packages.  He further asserted that a rocket, if powerful enough, could reach the Moon.

That latter assertion was the beginning of the mocking of Dr. Robert Hutchings Goddard.  Probably because Goddard’s report was too technical for lay journalists to understand, the press reflexively dismissed Goddard’s vision of journeys to other worlds as utter nonsense.  Newspaper editors steadfastly proclaimed Moon flights to be impossible by reason of the fact that there is no air in the vacuum of space for the rocket to “push against”.  Not only was their pronouncement a brazen misreading of Newton’s Third Law of Motion, Goddard would prove - through static testing - that it was indeed possible for a rocket to fly through a vacuum.

Nevertheless, newspaper editors - not about to let themselves be hampered by their lack of scientific acumen - labeled Goddard a crackpot, and even gave him a derisive nickname:  “Moon Man”.

As far as Goddard was concerned, the feeling was mutual.  Goddard felt - entirely justifiably - that he had been subjected to mockery without having first been given a fair opportunity to present his case in a way that would be understandable to the general public.  Thus began a lifelong mutual dislike between Goddard and the mainstream press.

Unfortunately, Goddard’s personality quirks served only to reinforce the press’ perception of him.  While far from being a crackpot, Goddard had his share of eccentricities.  He was withdrawn, reclusive, often preferring to work in isolation.  In these and other ways, he was indeed the stereotypical obsessed scientist, single-mindedly relentless in his pursuit of knowledge.

However, Goddard seemed not to care what the press thought of him.  If nothing else, he at least enjoyed the respect of his scientific colleagues.  And he had his work to do.

There was another equally sad aspect to Goddard’s life.  He did not live to see his ultimate dream realized.  He died 24 years before the first Moon landing.

But, in the final analysis, it was Goddard who emerged victorious.  The Apollo series of Moon missions proved irrefutably that rockets could indeed travel through space and carry men to other worlds.  To its credit, The New York Times printed a belated apology to Goddard.  In an editorial published the day after the launch of Apollo XI, the newspaper conceded that the “Moon Man” had been right from the beginning.

Goddard would receive posthumously the accolades that eluded him during his lifetime.  Including having NASA’s Greenbelt, Maryland research facility named the Goddard Space Flight Center in his honor.

“Every vision is a joke – until the first man accomplishes it,” Goddard once said.

Yes, and what visions.  Weather satellites, deep-space probes, men walking on the Moon, space stations, and global communications - all of the benefits we derive from space that we take for granted.  But not one of them would have been possible without the pioneering work of Dr. Robert Hutchings Goddard.

You young people should follow Goddard’s example.  Goddard’s story re-affirms the fact that nothing in life that is worthwhile ever comes easily; and that all kinds of setbacks will be encountered along the way; and that success is never guaranteed.

But Goddard’s story re-affirms also the fact that, by combining a momentary flash of insight with decades of hard work, one man can make a difference.  One man can change the world.

Study hard, kiddies.

 Sources:  The Robert Hutchings Goddard sites at http://www.clarku.edu, http://www.istp.gsfc.nasa.gov, http://www.gsfc.nasa.gov, http://140.232.15/goddardfolder, http://www.spaceline.org, and http://inventors.about.com
 

For the week beginning September 30, 2001

Flash’s Astronomical Fact #102

In the previous edition of Flash’s Astronomical Facts, I related the story of how space scientist Dr. Robert Hutchings Goddard became (in 1926) the first to launch successfully a liquid-fueled rocket.

While the concept of the liquid-fueled rocket is universally regarded as Goddard’s most important contribution to the science of rocketry, it was by no means his only one.  Goddard racked up an impressive list of achievements - including a number of “firsts” - over the course of his nearly thirty years of tireless, dedicated research. Among other things, Goddard…

…was the first to work out the fundamental mathematics of launching a rocket to the Moon (1912).

…received (in 1914) two U.S. Patents: One for the concept of the liquid-fueled rocket, the other for the concept of the multi-stage rocket.  In all, Goddard would accumulate 214 U.S. Patents over the course of his career.

..was the first to send a scientific payload aloft aboard a rocket (in 1929, he sent a camera, a thermometer, and a barometer to high altitude).

…was the first to develop a gyroscopic stabilizing apparatus for rockets (1932).

…was the first to position deflector vanes in the rocket motor blast as a means of providing guidance (1932).

…designed the first man-made object (a rocket) to travel faster than sound (1935).

…was the first to launch successfully a rocket with the engine pivoted on gimbals and guided by a gyroscopic mechanism (1937).

…was the first to send a rocket to an altitude of 9000 feet (his highest flight) (1937).

With his track record, Goddard was able to secure funding for his research from such bodies as the Smithsonian Institution, and the Daniel & Florence Guggenheim Foundation.  In addition, he was granted leaves of absence from Clark University to conduct his experiments.

One would suppose that Goddard's successes in the field of rocketry brought him universal public acclaim during his lifetime.  And one would be wrong.  We will examine that aspect of Goddard’s life in the next edition of Flash’s Astronomical Facts.

 Sources:  The Robert Hutchings Goddard sites at http://www.clarku.edu, http://www.istp.gsfc.nasa.gov, http://www.gsfc.nasa.gov, http://inventors.about.com, and http://140.232.15/goddardfolder
 

For the week beginning September 23, 2001

Flash’s Astronomical Fact #101

In the previous edition of Flash’s Astronomical Facts, I related a brief biography of American scientist Dr. Robert Hutchings Goddard.  However -  as you are about to see - the story of "The Father of Modern Rocketry” is very much worthy of more detailed examination. 

Goddard was a consummate workaholic.  Even while carrying a heavy workload as a full professor of physics and Director of the Physical Laboratories at Clark University, Goddard devoted every available spare minute of his time to his pioneering research in the field of rocketry.

Goddard was one of those rare scientists, someone who was equally adept at tackling the practical as well as the theoretical.  Not only did he work out the mathematics and physics of rocket propulsion, he designed and built working models of rockets.

Goddard’s greatest contribution to the science of rocketry was the concept of the liquid-fueled rocket.  Since their invention by the Chinese some 800 years before, all rockets had been powered by solid fuels of one sort or another.  Unfortunately, all such fuels produce a relatively low exhaust velocity.  Enough to send fireworks into the sky or launch a military rocket at a foe on the battlefield; but certainly not enough to send payloads to high altitudes, let alone into orbit, much less breaking free of the Earth’s gravitational field.  Goddard believed that rockets powered by liquid fuels could produce exhaust velocities sufficient to send payloads into outer space.

On March 16, 1926, Goddard became the first to launch successfully a rocket powered by liquid fuels.  Using gasoline as the fuel and liquid oxygen as the oxidizer, his experimental rocket achieved a maximum altitude of 41 feet.  The flight lasted all of 2.5 seconds.  It was the first “baby step” of a concept that would result eventually in a “giant leap”.

If that were all that Goddard had accomplished in the field of rocketry, his place in history would have been secured.  But Goddard’s experiments, performed over a period of thirty years, would lead to a number of significant breakthroughs – which we will examine in the next edition of Flash’s Astronomical Facts.

 Sources:  The Robert Hutchings Goddard sites at http://www.clarku.edu, http://www.istp.gsfc.nasa.gov, http://www.gsfc.nasa.gov, and http://www.allstar.fiu.edu
 

For the week beginning September 16, 2001

Flash’s Astronomical Fact #100

In commemoration of the 100th edition of Flash’s Astronomical Fact of the Week, I - the Grand Master of The Official Flash Kellam Website - herewith present the first of a multi-part series on one of history’s greatest space scientists.

One of NASA’s most important research facilities is the Goddard Space Flight Center in Greenbelt, Maryland.  It was dedicated on May 1, 1959, and is named for an American scientist, Dr. Robert Hutchings Goddard (1882 – 1945).

And just who was Dr. Robert Hutchings Goddard?

Goddard, a brilliant physicist and engineer, is universally considered to be “The Father of Modern Rocketry” - and with good reason.

Goddard’s story began when he was seven years of age.  Like Sir Isaac Newton, Robert Hutchings Goddard had an epiphany involving a tree.  Only in Goddard’s case, it was a cherry tree rather than an apple tree.

The date was October 19, 1899.  Goddard had climbed up a family friend’s cherry tree.  Soon, he began to daydream.  From high up in the tree, he looked down on the meadow below, and envisioned how a rocket would look rising into the sky on its way to Mars. 

Goddard had climbed up the tree to prune some branches.  He climbed down the tree ready to dedicate his life to making his vision a reality.

October 19 became Goddard’s “Anniversary Day”.  Every October 19, Goddard would plan his activities for the next twelve months.

But not everything went according to plan.  Goddard was hampered by occasional bouts of sickness.  Illness caused him to miss nearly two years of school (1899-1901).  Later, he spent many months (1913-1914) recovering from a case of tuberculosis.

Goddard’s enthusiasm sometimes got him into trouble.  In 1907, while a student at the Worcester Polytechnic Institute, he was nearly expelled when an experiment involving a rocket motor powered by powdered fuels went awry, sending black smoke pouring out of the basement of the physics building.

Despite those and other setbacks, Goddard continued his education.  Listed below are the highlights of his rise through the ranks of academia:

Bachelor of Science degree from Worcester Polytechnic Institute (1908).
Master of Arts degree from Clark University (1911).
Ph.D. in physics from Clark University (1911).
Research instructor in physics, Princeton University (1912-1913).
Instructor in physics, Clark College (1914-1915).
Assistant professor of physics, Clark College (1915-1919).
Associate professor of physics, Clark College (1919-1920).
Full professor of physics, Clark University (1920-1943).
Director of Physical Laboratories, Clark University (1923-1943).

Along the way, Dr. Goddard would hold memberships in several of America’s most prestigious scientific societies.

Even if Dr. Goddard had done nothing else during his life, he still could claim to have had a brilliant career as one of America’s most accomplished scientists and educators. 

But there is much more to Goddard’s life; too much to tell in just one sitting.  So I will have more to say on the life of Dr. Robert Hutchings Goddard in the next edition of Flash’s Astronomical Facts.

 Sources:  The Dr. Robert Hutchings Goddard sites at http://www.clarku.edu, http://www.istp.gsfc.nasa.gov, and http://www.gsfc.nasa.gov
 

For the week beginning September 9, 2001

Flash’s Astronomical Fact #99

In the previous edition of Flash’s Astronomical Facts, we discussed the basics of radio astronomy:  The science of studying celestial bodies by means of the radio waves they transmit.  In this edition, I will relate in brief the brief history of radio astronomy.

In 1932, Karl Jansky, a Bell Telephone Laboratories engineer, was assigned to track down the source of a mysterious static that was interfering with radiotelephone communications.  He found the source of the interference, but found also that it was not terrestrial in nature.  Jansky’s investigation had revealed the existence of interstellar radio waves.

But while the scientific community did not dispute Jansky’s findings, neither did it see immediately how interstellar radio waves might be employed as a tool of astronomical research. The pioneering work in radio astronomy was literally a one-man undertaking.  In 1937, Grote Reber assembled in his back yard a thirty-one foot parabolic receiving dish.  By 1944, he had completed the first map of radio sources in the Milky Way Galaxy.

Radio astronomy has grown enormously since then.  Today, thousands of parabolic dishes and rectangular receiving arrays dot the landscape around the world, aiding astronomers in their scientific inquiries.

Radio astronomy will be discussed in more detail in future editions of Flash’s Astronomical Facts.

 Sources:  Voyage Through the Universe/The New Astronomy, Voyage Through the Universe/The Third Planet, a Time-Life Book Series
 

For the week beginning September 2, 2001

Flash’s Astronomical Fact #98

In the previous edition of Flash’s Astronomical Facts, I described the basics of optical astronomy:  The science of studying celestial bodies by means of the visible light they transmit.  Visible light, a form of electromagnetic (EM) radiation, propagates through space at a particular (and particularly narrow) range of frequencies - frequencies to which our eyes are receptive.

But optical astronomy, however useful, has its limits as a tool of astronomical research.  For instance, nebulae - vast clouds of interstellar gas and dust - block waves of visible light.

However, visible light comprises only a very narrow band of the EM spectrum.  Do celestial bodies emit or reflect other frequencies of EM radiation?  And could scientists study the heavens in those frequencies?

Celestial bodies do, in fact, transmit EM radiation in many frequencies of spectrum.  And scientists have instruments capable of detecting EM radiation of those frequencies.

But most such instruments are useless to Earth-bound astronomers because our planet’s atmosphere reflects or absorbs virtually all frequencies of EM radiation save visible light.  Cosmic rays, gamma rays, X-rays, and all but a select few frequencies of ultraviolet, infrared, and microwave radiation never reach the Earth’s surface from outer space.  Thus, the same atmosphere that protects life on our planet from being fried to a crisp by interstellar radiation of those frequencies also makes it impossible for Earth-bound astronomers to study the heavens in those frequencies.

However, there is a way for Earth-bound astronomers to study celestial bodies other than by means of visible light.  There exists another form of EM radiation that is capable of reaching our planet’s surface from outer space; a form that, like visible light, poses no threat to life on Earth:  Radio waves.

Scientific instruments can detect radio waves from beyond the Earth just as surely as your nightstand instrument can pick up signals from your local station.  By means of special imaging systems, astronomers can produce computer-generated pictures showing how an interstellar radio source would appear to someone whose eyes were sensitive to EM radiation of the radio frequency band.  And unlike waves of visible light, radio waves can pass through interstellar nebulae - thus allowing astronomers to see what lies beyond.   The science of studying celestial bodies by means of the radio waves they transmit is called radio astronomy.

In the next edition of Flash’s Astronomical Facts, I will relate the brief - very brief - history of radio astronomy.

 Sources:  Voyage Through the Universe/The New Astronomy, Voyage Through the Universe/The Third Planet, a Time-Life Book Series
 

For the week beginning August 26, 2001

Flash’s Astronomical Fact #97

Beyond the limits of the Earth lie stars, planets, and other bright objects.  Known collectively as celestial bodies, they are like dazzling ornaments sewn into the fabric of space.  Without these adornments, the night sky would be naught but a dull shroud of black.

We are able to see the celestial bodies of the night sky because said bodies emit or reflect visible light:  Waves of electromagnetic (EM) radiation propagating through space at a particular (and particularly narrow) range of frequencies - frequencies to which our eyes are receptive.

In addition to making skywatching possible, visible light makes possible also the scientific study of outer space.  By means of telescopes and other optical instruments, the visible light from distant bodies can be gathered and magnified, thus affording astronomers a better view of the heavens than any they could hope to obtain using the eye alone.  The science of studying celestial bodies by means of the visible light they transmit is called optical astronomy.

Optical astronomy has revealed many of the secrets of the universe.  However, the method does have its limits.  For instance, dispersed throughout our galaxy are vast clouds of interstellar gas and dust, called nebulae.  Nebulae can block waves of visible light, thus making it impossible for astronomers to see what lies beyond.

However, science is nothing if not resilient.  When one technique proves ineffectual, scientists investigate alternatives.

Do celestial bodies transmit forms of EM radiation other than visible light?  Do there exist scientific instruments capable of detecting EM radiation of those frequencies?  And can celestial bodies be studied in those frequencies?

It is a fact that celestial bodies do emit or reflect frequencies of EM radiation other than visible light; and it is also a fact that scientists have instruments capable of detecting EM radiation of those frequencies.  Unfortunately, Earth-bound astronomers cannot study the heavens in most of those frequencies because of a minor impediment:  Our planet’s atmosphere.

The Earth’s atmosphere absorbs or reflects most all frequencies of EM radiation save visible light.  Cosmic rays, gamma rays, X-rays, and all but a select few frequencies of ultraviolet, infrared, and microwave radiation never reach our planet’s surface from outer space.  Which is good, because most all frequencies of EM radiation other than visible light are – in one way or another, to one degree or another - inimical to life on Earth.  But, in shielding us from interstellar radiation of those frequencies, the atmosphere precludes Earth-bound astronomers from studying the heavens in those frequencies.

However, there is a way for Earth-bound astronomers to study the heavens other than by means of visible light.  We will examine that aspect of astronomy in the next edition of Flash’s Astronomical Facts. 

 Sources:  Voyage Through the Universe/The New Astronomy and Voyage Through the Universe/The Third Planet, a Time-Life Book Series
 

For the week beginning August 19, 2001

Flash’s Astronomical Fact #96

At the time of the formation of the Solar System, the innermost planet – Mercury – spun on its axis at a dizzying rate, completing one full rotation in perhaps as little as eight Earth hours.

Today, several billion years later, it takes Mercury 1,407 Earth hours – more than fifty-eight Earth days – to complete one full rotation.

Obviously, something has stolen a great deal of Mercury’s rotational velocity.  And the thieving culprit is… tidal forces.

Tidal forces result from the gravitational interaction between two or more massed bodies.  The Sun's powerful gravity produces tides on every planet in the Solar System to one extent or another.  But it is Mercury - the planet closest to the Sun - that experiences tidal effects to the greatest degree.

A complex interplay of gravitational forces between the Earth, the Sun, and the Moon produces on our planet ocean tides and - to a far lesser extent - land tides.  But Mercury has neither moons nor oceans.  Consequently, only the Sun produces any significant tides on Mercury - and then only in the form of land tides.

Because Mercury is a large body and not a single point, the side of the planet that faces the Sun (the near side) is closer to the Sun than the side that faces away from the Sun (the far side).  Since gravitational force is inversely proportional to distance, the Sun's gravitational pull is greater on Mercury's near side than on its far side.

And exactly as you might intuit, the Sun's gravitational attraction is strongest at the point on Mercury's near side that faces directly the Sun.  This causes the formation at that point of a land tide "bulge". 

At the same time, another tidal bulge forms on Mercury's far side at the point directly opposite the near-side bulge.  This is because, at that point on the far side, the Sun's gravitational pull is at its weakest.  As a result, the rest of the planet - for lack of a better term - leaves the far side behind in order to move towards the Sun.  Thus, the planet has twin tidal bulges, one each at the points of strongest and weakest gravitational attraction.

Now, as Mercury orbits the Sun, the near-side bulge does not face directly towards the Sun, nor does the far-side bulge face directly away from the Sun; rather, both bulges are offset at a slight angle to a line directly between Mercury and the Sun.  This happens because a point on the rigid surface of a land mass can neither bulge immediately nor spring back readily - or, at least, certainly not as quickly as the fluid surface of an ocean.  Thus, each time a tidal bulge is created at a particular point on the surface of Mercury, it retains that shape for a brief time even after the planet's rotation carries that point away from the Sun.  And keep in mind that, because the planet is rotating, a new point on the planet's surface comes to face the Sun even as the previous point is carried away.  In other words, tidal bulging is a continuous process.  And while these land tides are small - no more than a few centimeters height differential - the near-side bulge remains the point closest to the Sun even after the planet's rotation carries it away from the line of direct gravitational attraction.

And that is what is causing the planet to slow down.  While the planet’s rotation seeks to carry the near-side bulge away from the Sun, the Sun’s gravity tries to pull it back in the direction opposite.  Thus, with each rotation, the planet loses an infinitesimal amount of rotational velocity.  And over the course of billions of years, that infinitesimal amount adds up to a lot.

And what is Mercury’s long-term fate? Barring some cosmic event of cataclysmic proportions, the process of tidal slowing will continue until, finally, Mercury and the Sun will become gravitationally locked.  When that happens, one side of Mercury will face perpetually the Sun, the same way (and for the same reason) that one side of the Moon now faces perpetually the Earth.

 Source:  Voyage Through the Universe/The Near Planets, a Time-Life Book Series
 

For the week beginning August 12, 2001

Flash’s Astronomical Fact #95

The Solar System consists of nine planets. From innermost to outermost, they are:  Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto.

Five extraterrestrial worlds - Mercury, Venus, Mars, Jupiter, and Saturn - were known to the ancients because said worlds reflect enough sunlight to reveal their presence to Earthly observers - even those viewing the heavens with just the unaided eye.

The remaining extraterrestrial planets  - Uranus, Neptune, and Pluto - are too small and/or too distant and/or too dark to reflect enough sunlight to make their existence known to naked-eye skywatchers.  Thus, these worlds remained unknown until after the invention of the telescope in 1608.  Uranus was discovered in 1781; Neptune in 1846; and Pluto in 1930.

Because their reflected sunlight is visible to the unaided eye, Mercury, Venus, Mars, Jupiter, and Saturn are known collectively as the visible planets.  Uranus, Neptune, and Pluto are not among the visible planets.

At least, not usually.  When viewing conditions are at their most favorable, Uranus - the planet next out beyond Saturn – can be seen with the unaided eye.

Just such favorable conditions are due shortly.

On August 15, 2001, Uranus will come into an orbital position called opposition (that is, Uranus will be directly opposite the Sun as seen from the Earth).  Uranus will rise in the east at dusk, stay out all night, and set in the west at dawn.  A full discussion of the concept of opposition is beyond the scope of this essay.  But these are the essential points:  When Uranus (or, for that matter, any outer planet) is at opposition, it is also at or near its closest approach to Earth.  Moreover, a planet at opposition presents its entire lighted half to the Earth.  In other words, an outer planet at opposition is just about as close and as bright as it ever can be.

Just three days later, on August 18, 2001, there will be a New Moon (that is, the Moon will come directly between the Sun and the Earth).  With the Moon’s lighted half facing fully away from the Earth, the night sky will be optimally dark. 

This combination of circumstances (Uranus at near-maximum brightness, the Earth's night sky at near-maximum darkness) makes August 18, 2001 the day on which you will have the best chance to see the planet Uranus with your unaided eye.  Uranus will arc low in the north in the vicinity of the constellation Capricornus (The Sea Goat).  Capricornus is a relatively faint constellation, but its brightest stars form a quasi-triangular shape that some have likened to an upside-down bicorn hat (such as would have been worn by Napoleon).  At the triangle's left corner is the constellation's brightest star, Delta Capricorni, known also as Deneb Algedi.  The planet Uranus will be slightly above and to the right of Deneb Algedi.

As you do when you go meteor hunting, find a safe location far away from city lights, give your eyes time to adjust to the darkness, then make an attempt to find the planet Uranus.  Take along a folding lounge chair.  Not only will the lounge chair afford you greater comfort, it will enable you to keep your head steady. Take along also a telescope or a good pair of binoculars so that you can view the planet with both the aided and the unaided eye.

Uranus has a magnitude of 6.0.  A full discussion of the concept of visual magnitude likewise is beyond the scope of this essay.  But this is the essential point:  Magnitude 6.0 objects are the faintest objects in the night sky that are visible with the unaided eye.

Catching a glimpse of our solar system’s elusive seventh planet with the naked eye alone is a difficult proposition even under the best of circumstances.  That having been said, August 18, 2001 will be your best chance for many years to come; so mark that date on your calendar.  If your eyesight is good and the weather is clear, there is a good chance that you will be able to see the planet Uranus with your unaided eye.

One more thing:  Here is a clue that will enable you to distinguish Uranus from the stars.  Uranus is green in color and shines steadily.  Stars twinkle – and none of them are green.

 Sources:  The Old Farmer’s Almanac, Voyage Through the Universe/Atlas, a Time/Life Book series, the Uranus Opposition site at http://www.skypub.com, the Capriconus sites at http://www.astro.uiuc.edu and http://www.r-clarke.org.uk, the “Why do Stars Twinkle while Planets Shine Steadily?” sites at http://ww.dsy.de and http://exosci.com, and the Physics FAQ site at http://www.math.ucr.edu
 

For the week beginning August 5, 2001

Flash’s Astronomical Fact #94

The first artificial satellite was launched on October 4, 1957.  The only instrument it carried was a radio transmitter to establish its presence.

Later satellites would carry aloft more instruments - such as detection equipment designed to take measurements of the space environment, and radio transmitters to telemeter the data to Earth.  The data provided by such satellites gave Earth-bound scientists a much clearer picture of the nature and structure of outer space.  The Van Allen radiation belts that surround the Earth were detected first by satellite instruments.

Around this same time, scientists began to ponder other uses for satellites beyond basic scientific investigation. Some wondered if satellites could be employed for weather observation. 

Thus was born the concept for the Television and Infra-Red Observation Satellite (TIROS).

The idea was to mount a television camera on a satellite, place it into orbit, and have it transmit to Earth real-time images of cloud movements; no different in principle than having an aerial reconnaissance plane photograph troop movements.  By tracking the movements of clouds, the positions of the accompanying highs, lows, and fronts could be determined.  Another camera mounted on the satellite, sensitive to infra-red radiation, would detect heat waves.  By measuring the intensity of the heat waves, the temperature of the atmosphere could be determined.  These satellite-mounted instruments thus would provide weather forecasters with a much clearer overall picture than anything they could discern even by analyzing reports from hundreds of ground stations.

The problem was, nothing like this had ever before been attempted.  And the only way to find out if the concept was feasible was to put up the money, build the satellites, and take the chance.

Ultimately, they did take the chance, and well that they did.  The TIROS program turned out to be a smashing success.  A total of ten TIROS satellites, designated TIROS-1 through TIROS-10, were built and launched between the years 1958 and 1967.  The first satellite in the series to be sent aloft, TIROS-1, was launched on April 1, 1960.   It transmitted to Earth that same day the first television pictures of our planet ever taken from orbit.

The most important purpose served by TIROS satellites was to track the movements of hurricanes.  The images they returned to Earth aided meteorologists in forecasting the course of hurricanes, thus providing plenty of advance warning to communities in harm’s way.  By giving people the time they need to evacuate, TIROS and successor weather satellites have saved countless lives.

TIROS satellites were built by the Radio Corporation of America (RCA).  To save money on production costs, each TIROS satellite resembled closely all of the others in the series.  A typical TIROS satellite was roughly cylindrical in shape, some 107 cm (42 inches) in diameter and 48 cm (19 inches) high.  It was constructed mostly of aluminum, and weighed 122 kg (270 pounds).  TIROS was powered by some 9200 solar cells placed on the outside of the satellite.  These solar cells charged continuously some 63 nickel-cadmium (NiCad) batteries. Mounted on the bottom of TIROS were two cameras, one a low-resolution television camera, the other an infra-red camera.  Also mounted on the bottom were a series of transmitting antennae.  Three pairs of solid-propellant rockets, attached to the perimeter of TIROS, could be employed to correct the orbiting satellite’s attitude relative to the Earth, thereby assuring that the cameras always would be looking down towards the planet’s surface.

A typical TIROS satellite was launched by a three-stage Delta rocket and set to go around the Earth in a circular polar orbit (that is, one that would take the satellite alternately over the north and south geographic poles).  TIROS orbited the Earth at a height of 600 km (373 miles).

There was a specific reason for placing TIROS satellites in polar orbit, rather than the usual equatorial orbit.  As the satellite orbited the poles, the Earth would rotate beneath; thus, a single TIROS eventually would pass over - and photograph - the entire surface of the Earth.  By April 1962, enough operational TIROS satellites were in orbit at the same time to give twenty-four hour coverage of the whole planet.

All of the original ten TIROS satellites long since have gone out of operation.  But, the TIROS program was so successful, it led to a number of successor programs, such as TOS (TIROS Operational System); ITOS (Improved TIROS Operational System); and, most recently, TIROS-N (for Next Generation).

Each of the original TIROS satellites was truly a pioneer.  Knowledge acquired by the deployment of each TIROS led to improvements in instrumentation, data programming, and operational systems.  And not just for later missions in the TIROS program, but for satellites in general.

 Sources:  The TIROS mission sites at http://sumadi.jpl.nasa.gov and http://www.earth.nasa.gov
 

For the week beginning July 29, 2001

Flash’s Astronomical Fact #93

The following true story is going to sound very familiar to anyone who has ever mislaid his car keys.

During Space Shuttle mission STS-33 (November 22-27, 1989), astronaut Manley L. “Sonny” Carter, Jr. lost his wristwatch somewhere aboard the Discovery.

The wristwatch was found aboard the Discovery by astronaut Loren J. Shriver - during Space Shuttle mission STS-31 (April 24-29, 1990).

Yes, you read that right – five months (and another launch) later!

Talk about lost in space.

 Source:  The Space Factoids site at http://www.spacetoday.org
 

For the week beginning July 22, 2001

Flash’s Astronomical Fact #92

The questions that follow pertain to the largest bathroom in your home or apartment.  First, where in that bathroom do you store the spare rolls of toilet paper?  And exactly how many spare rolls are in storage there right now?  Most importantly, can you access those stores from the seated position?

I did not ask the above questions in an effort to be funny.  I am trying to make a serious point.  If you have a desperate need for an item that is not available, then you have a problem on your hands.  The same applies to an astronaut aboard a spacecraft.  The difference is, if you run out of toilet paper, you can hop down to the supermarket and buy some.  What is an astronaut orbiting several hundred miles above the Earth’s surface supposed to do?

Planning a space mission is no easy task.  If the astronauts are to have a successful (that is, productive) flight, project managers first must determine - among other things - what kinds of supplies and equipment will be needed over the course of the mission.  Then, they must arrange for said supplies and equipment to be procured, and in the right amounts.  Finally, they must see to it that said supplies and equipment are stowed properly aboard the spacecraft before launch. 

In the early days of space exploration, manned space flights were very brief (in some cases, as little as fifteen minutes duration).  The astronaut needed next to nothing in the way of supplies and equipment beyond his spacesuit. 

But, as manned space flights became longer in duration, and astronauts were called upon to perform more tasks, it became necessary to procure and send aloft more supplies and equipment.  Not just in greater quantity, but in greater variety. 

Today's astronauts, operating aboard the Space Shuttle, may have to deal with as many as 5,000 loose items.  These items include - but are not limited to - tools, spare parts, food rations, and scientific instruments.  And the problem surely will be compounded aboard the International Space Station (ISS), where as many as 50,000 loose items might be on board at any one time. 

And yes, it is necessary to keep track of each and every one of those loose items.  And not just for inventory control and cost accounting purposes.  In a critical situation, the ability to locate a particular item could be of crucial importance.  For instance, suppose that a vital piece of equipment aboard the ISS needs repairs, but the astronaut cannot find the tool he needs to effect those repairs.  Did somebody place the tool in the wrong storage cabinet? Is the tool being used by another astronaut in a different section of the station?  Is it just floating around someplace?  Where is it?

To get a better handle on the problem, NASA is planning to “tag” each and every loose item with a microchip as thin as a postage stamp and about one-fourth the size.  Each tag will hold in its electronic memory all of the pertinent information about the object to which it is attached; information such as the item's name, its inventory control number, its cost, its proper place aboard the station, etc.  These electronic tags (and the data they hold) will be read at the incredible rate of 15,000 tags per second by means of a portable solar-powered infrared transmitter.  In this way, station personnel will never lose anything that is loose.

 Source:  The Space Factoids site at http://www.spacetoday.org
 

For the week beginning July 15, 2001

Flash’s Astronomical Fact #91

A handful of the world’s astronomical scientists remain engaged in the search for extraterrestrial intelligence.  By means of sophisticated receiving instruments, the investigators hope one day to pick up radio transmissions from intelligent beings living on other planets.

Of course, the probability of picking up a radio signal from an alien civilization depends on how many alien civilizations are out there.  And how many alien civilizations are out there depends on… what?

That was the question pondered by American astronomer Dr. Frank Drake.

In 1961, Drake developed a formula for estimating the number (N) of communicative intelligent civilizations in the galaxy.  This formula, called the Drake Equation, may be expressed as follows:

Below, I will define the variables of the Drake Equation and give you the numerical values that were assigned to them by scientists attending a 1961 conference on the possibilities of extraterrestrial life.

R_* is the rate of star formation in the galaxy.  Scientists estimate that, on average, ten stars form in the Milky Way Galaxy every year.  Therefore, R_*  = 10.

f_p is the fraction of stars that have planets.  The scientists at the conference posited that whenever a star forms, planets invariably form with it.  Thus, f_p = 1.

n_e is the number of “Earth-like” planets in each star system.  Drake was of the belief that at least one planet in every star system should be capable of supporting life as we know it.  Therefore, n_e = 1.

f_l is the fraction of those planets capable of supporting life that actually have life.  Those attending the conference presumed that any planet that is able to support life would - eventually - produce life.  Thus, f_l = 1.

f_i is the fraction of those planets with life that develop intelligent life.  The attending scientists believed that only one life-bearing planet in ten would give rise to intelligent life.  Therefore, f_i = 0.1.

f_c is the fraction of those planets with intelligent life that develop both the ability and the desire to communicate by radio.  This prospect was given only a one-in-ten chance.  Thus, f_c = 0.1.

L is the number for civilization life span (that is, the number of years that an intelligent civilization will continue to exist after developing radio communication).  Determining a numerical value for this variable produced the widest range of disagreement among the conference attendees - and for good reason. 

Because of the short span of time between the developments here on Earth of the first Marconi wireless transmitter (1894) and the first Alamogordo nuclear bomb (1945), the scientists deemed it reasonable to assume that any civilization that possessed the capability of radio communication almost certainly possessed - or soon would possess - nuclear weapons as well.

Keep in mind that this conference was held in the year 1961.  The Cold War was in full swing and the Cuban Missile Crisis was only a few months away.  Perhaps expressing their own immediate hopes and fears, the astronomers at the conference came up with a wide numerical range for L.

Some of the attending scientists - possibly echoing the fatalistic view commonly heard during the 1960’s - believed that any civilization possessed of nuclear weapons was doomed to destroy itself, if only accidentally.  Therefore, they gave communicative intelligent civilizations (us as well as them) little hope for long-term survival.  Their figure for L was 1,000 years.

But other scientists at the conference gave communicative intelligent civilizations (terrestrial as well as extraterrestrial) a little more credit.  They held the view that any race smart enough to invent nuclear weapons also would be wise enough not to use them.  Therefore, civilization could continue for as long as the planet was capable of supporting life.  Their figure for L was 1,000,000,000 years.

Substituting the values for the variables, the Drake Equation produced the following figure for N:

N = 10 x 1 x 1 x 1 x 0.1 x 0.1 x (1,000 to 1,000,000,000) = 100 to 100,000,000

Thus, the Drake Equation suggested that there should be from 100 to 100,000,000 worlds in the Milky Way Galaxy inhabited by intelligent beings capable of radio communication.  Admittedly, six orders of magnitude does not exactly narrow down the figure.

And therein lies the weakness of the Drake Equation.  The Drake Equation can provide little more than an educated guess as to the number of communicative intelligent civilizations in the galaxy; largely because not all of the numerical values assigned to the several variables are based on hard science.  Some values, such as the rate of star formation, can be determined objectively.  Other values, such as civilization life span, are completely subjective.  This subjectivity is what gives us the wide-ranging figure for N.

And therein lies the strength of the Drake Equation.  Because some of the values assigned to the several variables are based in whole or in part on opinion, the Drake Equation does one thing marvelously well:  It spurs discussion.

Whatever its faults, the Drake Equation remains fascinating in that it incorporates just about every aspect of science, from natural sciences to applied sciences to social sciences.

How about you?  What values would you assign to the variables of the Drake Equation?  And on what basis would you determine those values?  And after running the numbers, what figure would you get for N?

Get together with your friends and play the Drake Equation game.  Have everybody in the group run his or her numbers.  Then get ready to defend your figure for N in the lively debate that is sure to follow.

 Sources:  The Drake Equation sites at http://www.setileague.org and http://www.seti.org, the Marconi Radio site at http://www.alpcom.it, Voyage Through the Universe/Life Search, a Time-Life Book Series, Cosmos by Carl Sagan, and A Timetable of Inventions and Discoveries by Kevin Desmond
 

For the week beginning July 8, 2001

Flash’s Astronomical Fact #90

What follows is the third of an occasional series about flags with stars.  This entry in the series will be presented in three parts, of which this is the third.

In the two previous editions of Flash’s Astronomical Facts, we examined first how the American flag came to have its familiar design elements.  Then, we began a review of how the flag is revised to reflect the admission to the Union of new states.

Per the Flag Act of 1818, the stripes on the American flag are fixed at thirteen in number to represent the Thirteen Original Colonies that founded the United States.  But, whenever a new state (or block of new states) is admitted to the Union, the stars in the canton are increased in number accordingly and re-arranged into a new stylized pattern.  The revised flag is then introduced to, and becomes the official banner of, the United States on the next Fourth of July.

Over the years, there have been twenty-seven official flags of the United States.  Some of these flags had to be changed to reflect the admission of a single state.  Some lasted only one year.  Seven times in our history, the flag had to be changed because of the admission of a single state, only to be revised the year following.

The United States flag with the longest tenure to date was the 48-star flag, which served as America’s official banner for 47 years (1912 – 1959).  Ironically, the longest tenure was followed by one of the shortest.  With the admission to the Union of the state of Alaska in 1959, a 49-star flag was adopted, only to have to be revised the very next year with the admission to the Union of the state of Hawaii in 1960.

The current 50-star United States flag now has been in use for 41 years (1960 – present).  With America's territories and possessions disinclined to apply for statehood at this time and the District of Columbia statehood movement in remission, it is very likely that the present-day Stars and Stripes soon will attain the longest tenure of any official American flag.

Here are just some of the distinctions held by the flag of the United States of America:

The current American flag boasts fifty stars, the most to be found on any national banner with stars.  The flag of Brazil, the runner-up at twenty-seven stars, does not even come close.

The Star-Spangled Banner now has been in continuous use for 224 years, just one year fewer than the nation it represents.  True, the stars in the union have changed with the times.  But the basic design has been there since day one.  Only a handful of national banners, such as the flag of Denmark, can boast greater longevity.

And, as we examined a few weeks ago, it is the only flag ever to be planted on the surface of the Moon.

While the flags of other nations may have interesting designs of their own, no national banner is more readily recognized the world over than the American flag.  Its colors, lines, and design elements are known to all, from Peoria to Timbuktu – to the Sea of Tranquility.

 Sources:  An Album for Americans, by David H. Appel, The Boy Scout Handbook, and the American flag sites at http://www.icss.com, http://www.anyflag.com, http://www.midcoast.com, http://www.crwflags.com, and http://www.unicover.com
 

For the week beginning July 1, 2001

Flash’s Astronomical Fact #89

What follows is the third of an occasional series about flags with stars.  This entry in the series will be presented in three parts, of which this is the second.

In the previous edition of Flash’s Astronomical Facts, we examined how the American flag came to have its familiar design elements:  The horizontal stripes of red and white, and the blue union spangled with stars.

The first official flag of the United States sported thirteen stars in its union, one for each of America’s Thirteen Original Colonies.  Later, those same thirteen stars would represent the thirteen states of the newly independent United States of America.  The stars in the union were arranged in a stylized pattern to create an imaginary constellation.

Each of the stars on the American flag is equal in size to all of the others.  This is to symbolize that every state, regardless of its geographical area or population, is considered to be equally important to the whole of the Union.

Oh, and contrary to popular belief, no one particular star is intended to represent any one particular state. To link stars to states in such a way would be in conflict with our national goal to create “a more perfect Union”.

Following the admission to the Union of two new states (Vermont (1791) and Kentucky (1792)), it became necessary to revise the flag.  In 1795, the powers that be increased the number of stars in the blue union to fifteen and re-arranged them into a new stylized pattern.  But they increased also the number of stripes to fifteen since both the stars and the stripes were intended originally to represent the colonies (now states).  This revised flag would serve as America's official banner for the next 23 years.  Just such a fifteen-star, fifteen-stripe flag flew over Ft. McHenry while Francis Scott Key wrote the words for what later would become America's national anthem.

The admission to the Union of five more new states made yet another revision of the flag necessary in the year 1818.  Thankfully, somebody realized that if the number of stripes on the flag kept increasing in accordance with the number of states, the flag's field might eventually be composed of red and white pinstripes.  To prevent this - and to formalize the procedures by which the flag would be revised - Congress passed the Flag Act of 1818.  Per this legislation, the number of stars in the canton increases by one for each new state admitted to the Union; but the stripes are held forever to thirteen in number to represent the Thirteen Original Colonies that founded the United States.

I will have more to say on the American flag in the next edition of Flash’s Astronomical Facts.  And be sure to let your flag fly on the Fourth of July. 

 Sources:  An Album for Americans, by David H. Appel, The Boy Scout Handbook, and the American flag sites at http://www.icss.com, http://www.anyflag.com, http://www.midcoast.com, http://www.crwflags.com, and http://www.unicover.com
 

For the week beginning June 24, 2001

Flash’s Astronomical Fact #88

What follows is the third of an occasional series about flags with stars.  This entry in the series will be presented in three parts, of which this is the first.

With American Independence Day coming up on July 4, there is no better time than now to examine the single most famous of all starred flags:  The flag of the United States of America.

The American flag has one of the most interesting histories of any national banner; mainly because the flag, like the republic for which it stands, has changed over time.

We will begin by relating the story of how the Stars and Stripes came to have stars and stripes.

From the year 1707 through the Revolutionary War, the flag that flew over the American colonies was the British merchant banner, known also as the Queen Anne flag.  The Queen Anne flag was entirely red, save for a box in the banner's upper left hand corner (this box is called the flag's canton or union).  Occupying the canton of the Queen Anne flag was a smaller version of the British national banner, called the Union Jack.  The Union Jack is composed of a blue field overlaid by crosses of St. Andrew (white) and St. George (red).

The first formal (though not official) flag of the United States was the so-called Grand Union flag.  The Grand Union flag looked exactly like the Queen Anne flag - with one significant difference:  Whereas the Queen Anne flag sported a field of solid red, the field of the Grand Union flag was composed of alternating red and white horizontal stripes.  The symbolism was simple and straightforward.  By taking the red field of the British merchant banner and separating it with white stripes, the Patriots were letting it be known that the colonies were separating from England. 

The seven red stripes and six white stripes made for a total of thirteen stripes, one for each of the Thirteen Original Colonies.  To symbolize that each of the colonies was of equal importance, the stripes were made equal in width, and no one particular stripe is intended to represent any one particular colony.  The Union Jack in the canton was retained to acknowledge that England was America’s country of origin.  The Grand Union flag, known also as the Continental Colors, was adopted by George Washington and first flown over his headquarters outside Boston on January 1, 1776.  The Grand Union flag became the banner under which the Patriots fought during the early days of the Revolutionary War. 

However, many people did not like the design of the Continental Colors.  The presence in the canton of the Union Jack, intended simply as a symbolic acknowledgement of the mother country, was misinterpreted as being symbolic of America’s ambivalence towards independence.  Remember, at the time of the American Revolution, not everyone in the colonies favored rebellion.  A substantial number of colonists, called Loyalists, wished for America to remain part of the British Empire.  Thus, the Grand Union flag, with its combination of design elements, looked like the perfect banner - the perfect banner for a nation that could not make up its mind, that is.

To eliminate any ambiguities, the flag was re-designed.  The red and white horizontal stripes were retained, and they would serve well enough to acknowledge England as the mother country and the colonies' separation from her.  But the crosses of St. Andrew and St. George were removed entirely from the flag’s canton.  Into the blue union were placed thirteen small, white, five-pointed stars (called pentagrams). As with the stripes, there was one star for each of the Thirteen Original Colonies.  The stars in the union were arranged in a stylized pattern to create an imaginary constellation.  By using stars to represent the colonies, the Patriots were, symbolically, making "an appeal to heaven" for divine guidance and deliverance. 

The Continental Congress officially approved and adopted the re-designed flag on June 14, 1777.  Americans still celebrate June 14 as Flag Day in commemoration of this event.

We will examine further the American flag - particularly its stars - in the next edition of Flash’s Astronomical Facts.

 Sources:  An Album for Americans, by David H. Appel, The Boy Scout Handbook, and the American flag sites at http://www.icss.com, http://www.anyflag.com, http://www.midcoast.com, http://www.crwflags.com, and http://www.unicover.com
 

For the week beginning June 17, 2001

Flash’s Astronomical Fact #87

Sometimes, the worlds of science fact and science fiction overlap in fascinating ways.  Consider the following:

Mimas (pronounced “My-muss”) is the innermost of Saturn’s nine largest moons.  British astronomer Sir William Herschel discovered Mimas in the year 1789.  In classical mythology, Mimas was one of the Titans slain by Hercules.  Mimas is 392 km (244 miles) in diameter, making it the largest of Saturn’s so-called “inner moons”, the ones that maintain the shape of Saturn’s rings through their gravitational influence.

As featured in the movie Star Wars (1977), the Galactic Empire’s supreme weapon was the Death Star, a battle station the size of a small moon.  The Death Star was almost perfectly spherical in shape, save for a single large parabolic depression in its northern (upper) hemisphere.  This parabolic depression was the focusing lens for the superlaser, a directed-energy beam capable of destroying an entire planet.  The focusing lens was huge, its diameter being about one-third the diameter of the Death Star itself.

Well, those two sets of facts are all very interesting, you may be thinking.  But what does one have to do with the other?

Just keep reading.  It all will become clear in due course.

During Voyager I’s flyby of the planet Saturn in 1980, its cameras took close-up pictures of several of Saturn’s moons (Mimas among them), which allowed their surface details to be discerned with unprecedented clarity.  Mimas’ most prominent surface feature is an immense meteor impact crater.  To judge by the size of the crater, the meteor that struck Mimas had to have been enormous (that is, enormous relative to the size of the satellite).  Fracturing on the surface of Mimas directly opposite the crater suggests strongly that the meteor came quite close to reducing the Saturnian moon to rubble.  The crater is officially named Herschel, after the discoverer of Mimas.

Again, that is all fine and well.  But what is the connection between Mimas and the Death Star?

This is the connection.

Relative to the size of the body struck, Herschel is one of the largest impact craters in the entire solar system.  Herschel is about 130 km (81 miles) in diameter, which makes the crater about one-third the diameter of Mimas itself.  As a result, the satellite Mimas bears an uncanny resemblance to the Galactic Empire’s ultimate weapon. 

And here is where science fact meets science fiction.  The crater known officially as Herschel it is known unofficially as... Deathstar.

 Sources:  The Mimas sites at http://www.deepspace.ucsb.edu, http://www.badastronomy.com and Voyage Through the Universe/Moons and Rings, a Time-Life Book Series
 

For the week beginning June 10, 2001

Flash’s Astronomical Fact #86

In the two previous editions of Flash’s Astronomical Facts, we examined some of the political and engineering obstacles that had to be overcome in order to raise an American flag on the Moon. In this edition, the last of the series, we will review – among other things – how well it went when the astronauts of Apollo XI actually planted the Stars and Stripes on the lunar surface.

The NASA engineering team of Jack Kinzler (Chief of Technical Services Division) and Dave McGraw (Deputy Division Chief) had worked out all of the technical problems.  They had designed a flagpole assembly that was compact, lightweight, and – most importantly – deployable by moonwalking astronauts whose range of motion would be limited by their bulky, pressurized spacesuits.

They had managed also to keep costs low.  The 3 foot x 5 foot nylon flag was purchased for $5.50, and the aluminum tubing for the pole cost another $75.00.  The insulating materials and protective shroud needed to shield the flag and flagpole assembly from heat damage during the descent and touchdown phases (the shroud was attached to the outside of the LEM (Lunar Excursion Module) so as to be readily accessible to the astronauts) cost only a few hundred dollars more.

Several prototype assemblies were produced; not only to prove that the equipment would work as intended, but also to provide extra sets for the astronauts to put together during EVA (Extra-Vehicular Activity) training.

Everything at NASA is done in accordance with strict engineering protocols - and packing the flag and flagpole assembly for flight aboard Apollo XI was no exception.  The simple act of packaging flag and flagpole into a sleeve of insulated material required that five people check and double-check every phase of a precise, written, twelve-step procedure.  Placing the insulated sleeve into the protective shroud required four more precise steps.  Securing the protective shroud to the lunar descent ladder required another eleven precise steps.

The final decision to raise the Star-Spangled Banner on the Moon was made at the last minute, and by that I mean the verylast minute.  Kinzler, along with George Low (Manager of the ApolloSpacecraft Program), and Low’s personal secretary had to charter a Lear jet to make it to the Kennedy Space Center on time.  The flag package, along with a commemorative plaque, was attached to the exterior of the Lunar Excursion Module at 4:00 in the morning as the Saturn V booster sat on the launch pad.  Kinzler personally supervised the installation.

So, for all that effort, how did things go on the Moon?

Not as well as they might have.  To be certain that the flagpole was seated firmly and securely into the ground, NASA engineers figured that the base portion would have to be driven into the lunar surface to a depth of eighteen inches.  In fact, the engineers had painted a red ring around the base portion at the eighteen inch mark as an aid to the astronauts in judging the depth of penetration.

Despite their best efforts, however, the astronauts could drive the base only about nine inches - half the required distance - into the ground.  To this day, it remains uncertain as to whether the flag is still standing or if it was blown over by the ascent module’s engine blast.

Another problem arose when the horizontal crossbar was deployed.  The astronauts were unable to telescope it to its full length.  Therefore, the flag was not stretched to its full width.  Instead, the flag sported a slight “ripple”.  Actually, that turned out to be both good news and bad news.  The good news was, the ripple gave the impression of a waving flag.  The effect was so dramatic that future Apollo astronauts deliberately deployed their own flags in the same way.  The bad news was, the ripple gave the impression of a waving flag.  Conspiracy theorists who believe that the lunar landings were a hoax have long proclaimed this “ripple effect” to be irrefutable proof that NASA staged the whole event, possibly out in the southwest desert.  Only blowing winds could produce such a ripple in the flag, they say; and they will not be convinced otherwise. 

Still, on balance, it was well worthwhile.  The flag raising took only ten minutes out of the two and one-half hours that the astronauts actually were traversing the lunar surface.  But who remembers anything about all of those dull scientific experiments that Armstrong and Aldrin conducted during the balance of their moonwalk?  What we remember is the awe-inspiring image of the astronauts posing alongside the American flag.

Happy Flag Day, everyone!  And be sure to fly yours on June 14.

 Source:  The Moon Flag site at http://www.jsc.nasa.gov
 

For the week beginning June 3, 2001

Flash’s Astronomical Fact #85

In the previous edition of Flash’s Astronomical Facts, we reviewed the political ramifications of planting an American flag on the surface of the Moon.  In this edition, we will examine the technical obstacles that had to be surmounted in order to accomplish that great historical feat.

It may seem an easy thing to do: Just stow flag and flagpole aboard the Lunar Excursion Module (LEM), and put it all together when you get to the Moon.

Unfortunately, nothing involving space travel is ever that simple.  In order for Apollo XI astronauts Armstrong and Aldrin to raise the Star-Spangled Banner on the Moon, NASA engineers first had to overcome a number of technical problems. 

Robert Gilruth, Director of the Manned Spacecraft Center, charged Jack Kinzler, Chief of Technical Services Division, with the task of designing a flagpole assembly that could be set up on the Moon by spacesuited astronauts.  After his design was approved, Kinzler, in collaboration with Deputy Division Chief Dave McGraw, worked out the engineering specifics.  Described below are some of the problems they encountered - and how they solved them.

Because the Moon has no atmosphere, winds never blow across the lunar surface.  Consequently, the flag would always hang limp on the flagpole – unless some kind of horizontal support were provided.  The solution was to sew along the top edge of the nylon flag a hem through which a crossbar could be fed.  The crossbar would keep the flag upright along its width, so that it would appear to be waving in the wind.

Weight and space go for a premium on a space vehicle.  Therefore, the flag and flagpole assembly had to be light in weight and small to stow.  Moreover, it had to be placed aboard the craft where it would not interfere with the astronauts during flight, yet be readily accessible after touchdown.  Clever engineering solved all of these problems.  By using lightweight materials, flag and flagpole together weighed only nine pounds and seven ounces. The flagpole itself was a two-part assembly.  Both of its vertical sections could be collapsed like a mariner's spyglass for compact storage.  The horizontal crossbar, attached to the upper vertical section by means of a locking hinge, was likewise collapsible.  So that the flag and flagpole assembly would be readily accessible to the moonwalking astronauts, the components were packed into an insulated shroud (described below), and attached to the left side of the LEM’s lunar descent ladder.

The two-part assembly made it possible for the astronauts to set up the flag despite being constrained in their ability to reach, bend, and – most importantly - grasp by their bulky, pressurized spacesuits.  The assembly would be accomplished in two stages.  Stage 1:  The lower vertical section (the base) would be driven into the ground by means of a geologist’s hammer.  Once seated firmly into the Moon's surface, the lower vertical section would then be telescoped up to its full height.  Stage 2:  The upper vertical section (with attached horizontal crossbar) would then be assembled as follows:  First, the horizontal crossbar would be fed through the flag’s upper edge hem.  Second, the crossbar would be swung above the ninety-degree mark and then lowered back to ninety degrees where a catch would lock it in the horizontal position.  Third, the crossbar would be telescoped outwards to extend the flag to its full width.  Fourth, the upper vertical section would then be telescoped up to its full height.  Finally, the upper vertical section would be fitted into the lower vertical section.

The outer portion of the LEM would experience temperatures of up to 250 degrees F during the descent phase, and 2,000 degrees F (briefly) during the touchdown phase.  But the nylon flag could not withstand temperatures greater than 300 degrees F.  Therefore, flag and flagpole were packed inside a sleeve of thermal insulating material, which then was closed by means of a Velcro strip.  This sleeve in turn was placed inside an aluminum tube that was covered with Thermoflex insulation.  Finally, the insulated aluminum tube was slipped into a cylindrical shroud made of stainless steel.  The thermal protection worked.  The flag would never experience temperatures above 180 degrees F.

And so, with all of the technical problems resolved, the American flag was ready for its journey to the Moon.

But did you know that Apollo XI came close to taking off without the American flag on board?  We will examine that part of the story (and review what happened when the assembly actually was assembled) in the next edition of Flash’s Astronomical Facts.

 Source:  The Moon Flag site at http://www.jsc.nasa.gov
 

For the week beginning May 27, 2001

Flash’s Astronomical Fact #84

With Flag Day coming up on June 14, now is a good time to review one of the most significant events in vexillological history:  The raising of the American flag on the Moon.

That American astronauts made planting a flag on the surface of our satellite world look easy belies the fact that NASA engineers had to solve beforehand a number of very tricky technical problems (which we will examine in the next edition of Flash’s Astronomical Facts).  But even harder to handle than the engineering obstacles were the political ramifications.

It might seem odd that an act as simple as raising a flag on the Moon could ignite controversy; until you consider the role that flags have played throughout the history of discovery.

Explorers traditionally have carried their national banners with them on their journeys, to be raised over whatever new lands they might discover.  The flags served to indicate first landfall, definitive proof that “We were here first”.

However, flags have served also to indicate conquest.  And after lands are conquered, they are invariably appropriated.

It was just that dual symbolism that led to concerns when it became known that serious consideration was being given to having agents of the American government (i.e., American astronauts) plant an American flag on the surface of the Moon. 

Prior to the Apollo Moon flights, the United Nations adopted (on January 27, 1967) the Treaty on Principles Governing Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies.  This treaty (thankfully known simply as the Outer Space Treaty) states, in part, that all celestial bodies are the “common heritage of mankind” and are not subject to “appropriation” by any nation.  And the United States of America is a signatory to that treaty.

America’s critics, ever ready to believe the worst, saw the plan to raise the Stars and Stripes on the Moon as part of a plot by the United States to claim title to the Earth’s satellite world in violation of the treaty.  To allay such concerns, the United States issued a carefully worded document stating - clearly and unequivocally - that the placement of an American flag on the Moon would be done simply as a symbol of achievement and not of appropriation.  As you might expect, this declaration did little to assuage those who were predisposed to hate America. 

On February 25, 1969, NASA formed the Committee on Symbolic Activities for the First Lunar Landing.  The Committee’s task was to recommend symbolic activities that would not compromise crew safety or interfere with mission objectives, yet would signalize that the first Moon landing, this historic forward step of mankind, was accomplished first by the United States.

To placate America’s critics, some suggested planting on the Moon the United Nations flag in addition to the U.S. flag.  Some proposed raising the United Nations flag in lieu of the U.S. flag.  Some suggested that, instead of flags (with all their nationalistic baggage), a series of commemorative plaques be placed on the Moon.  Someone even thought that it would be clever to make a small metal U.S. flag one of the components of the solar wind experiment package.  And mind you, these were the more serious proposals!

But ultimately, one political consideration trumped all of the others.  The flight of Apollo XI was to be funded solely by the U.S. taxpayer.  This pretty much ensured that only the Star-Spangled Banner would be planted on the lunar surface.  After all, the argument went, “If the other nations of the world are not sharing the expense, then why should we Americans share the glory?”  Indeed, it is difficult to argue with that proposition.

And so, in the end, here is what was decided: Apollo XI astronauts would raise a 3 foot by 5 foot U.S. flag on the surface of the Moon, but also would carry aboard the lunar landing craft a set of 4 inch by 6 inch miniature flags of all fifty U.S. states, the District of Columbia, all U.S. territories, the U.N. member nations, and non-member nations, to be presented to their respective governors and heads of state upon return. 

Now, were there protests when the American flag - and only the American flag - was raised on the Moon?  A few one-world socialists and third-world crybabies pouted, whined, and threw tantrums.  But they turned out to be few and far between.  For as people across the globe watched on television as the flag of the United States was being raised on the Moon, they were compelled to confront a simple, yet profound truth:  Men from the planet Earth were standing on another world!

When you stop to consider the significance of that, arguments over flags suddenly become unimportant.

Okay, so much for the politics.  But what about the technical aspects involved in raising a flag on the Moon?  We will examine that part of the story in the next edition of Flash’s Astronomical Facts. 

 Source:  The Moon Flag site at http://www.jsc.nasa.gov
 

For the week beginning May 20, 2001

Flash’s Astronomical Fact #83

The Earth’s Moon sports a number of interesting surface features; and one of the most fascinating is a geologic fault called the Rupes Recta.  Translated literally from the Latin, Rupes Recta means “straight rock”.

Part of the allure of the Rupes Recta comes from the almost magical way that the feature (which is more like a fault strip than a fault line) seems alternately to blend in with, and then stand out against, the lunar surface.  This happens because the Rupes Recta lies almost directly on a line from north to south, with the fault’s eastern edge being slightly higher than the western edge.  Consequently, at those times when it is illuminated from the Moon’s west, the Rupes Recta’s entire surface is bathed in sunlight, and seems to blend in with its surroundings.  But at those times when it is illuminated from the Moon’s east, the Rupes Recta’s eastern edge casts a fairly wide shadow towards the Moon’s west, as though the Sun were projecting its rays over the top of a precipice.  This is what prompted early astronomers - who could see the stark shadow even in their crude telescopes - to give the feature its common name: The Straight Wall.

As it turns out, the name Straight Wall is misleading.  The term "wall" connotes a steep vertical cliff.  In actuality, the Rupes Recta takes the shape of a gentle, oblique slope (properly called a scarp).  And just how gentle is this slope?  The height differential between the top (eastern) edge and the bottom (western) edge of the fault varies from 240-300 meters (790-980 feet).  Yet the fault has a width of 2500 meters (8200 feet).  Apply a little elementary trigonometry, and it works out that the scarp has a slope of about seven degrees.

The Straight Wall is located on the eastern shore of the Mare Nubium (the so-called “Sea of Clouds”).  The exact lunar coordinates of this feature are 22.1 degrees south latitude and 7.8 degrees west longitude.  That is to say, the Rupes Recta lies just a little to the west and somewhat to the south of the exact center of the Moon's face. 

The best time to look for the Straight Wall is when the Moon is in its waxing gibbous phase (that is, a few days after First Quarter).  The shadow of the Rupes Recta will appear as a dark vertical line on an otherwise bright patch of the Moon's surface.  The prominent shadow can be seen even in the small backyard telescopes of amateur astronomers. 

As I said, the Wall part of the name is something of a misnomer; but the Straight part is not.  The Rupes Recta is indeed straight.  And just how straight is straight?  The Straight Wall extends for 110 km (68 miles) in an almost perfectly straight line!

 Sources:  The Straight Wall sites at http://www.salzgeber.at, http://science.ksc.nasa.gov, http://www.lafterhall.com, and http://lunar.arc.nasa.gov
 

For the week beginning May 13, 2001

Flash’s Astronomical Fact #82

Astronauts and cosmonauts never wear “off-the-rack” garments.  Every piece of their working apparel – from their coveralls to their flight suits to the Extravehicular Maneuvering Units they wear during spacewalks – has to be individually tailored to fit the intended wearer.  This is done for more than just the sake of a space explorer’s comfort.  An ill-fitting garment can compromise also work efficiency, and even safety.

In the earliest days of space exploration, such “custom-fitting” was not limited to the astronauts’ attire.  The seats in which they reposed during flight also had to be built to the man.

All of the original Mercury Seven astronauts were military pilots.  As such, they were accustomed to flying aircraft from the seated position.  The decision was made that, as astronauts, they would fly their space capsules from the same position - the only difference being that their seats would be rotated 90 degrees rearward.  Within the capsule, the astronaut would lie on his back with his legs up and bent at the knees.  In this position, the astronaut’s eyes would be facing the direction of flight at all times (except during re-entry).

The seats were fabricated from resilient materials that could compress and then rebound as needed to cushion the astronaut during blastoff.  Each seat had to be contoured to fit precisely the astronaut using it.  Each of the seven Mercury astronauts would use his individually-molded seat not only during actual flight, but also during every aspect of his training that involved subjecting his body to high-g forces (rocket sleds, centrifuges, etc.).

When not in use, the seven seats were set upright against the wall of a storeroom.  The presence of the empty seats, each contoured to match the body of a particular Mercury astronaut, gave the storeroom a whimsical nickname – “The Throne Room”.

 Source:  Life in Space, a Time/Life book
 

For the week beginning May 6, 2001

Flash’s Astronomical Fact #81

In an inspired bit of whimsy, astronaut Gus Grissom gave his Gemini III capsule the nickname Molly Brown, after the famed survivor of the Titanic disaster.  It was Grissom's humorous way of expressing his hope that the spacecraft would prove to be as unsinkable as the lady.

If Grissom seemed preoccupied with the possibility of his Gemini capsule sinking, it was not without good reason.  Consider what almost happened to him on his first space mission – Mercury-Redstone IV, a.k.a. Liberty Bell 7.  Shortly after splashdown, explosive bolts on the hatch of Grissom's Mercury capsule fired prematurely.  With the hatch blown and Navy recovery crews not yet in position, Liberty Bell 7 began to ship water and eventually would sink into the Atlantic Ocean.  And Grissom came close to ending up on the bottom of the sea with it.  Consequently, one could hardly blame Grissom for employing every possible means - rational or whimsical - of ensuring a safe (and unsaturated) mission.

So, did the flight of Gemini III end in a manner more to Gus Grissom's liking?

True to its name, the Molly Brown did not sink into the ocean.  It remained watertight after splashdown. This time, a Grissom-commanded capsule would stay on the surface.

That is not to say that Grissom, and his crewmate John Young, got off scot free.  Gemini III splashed down some eighty kilometers (fifty miles) short of the Navy recovery ship U.S.S. Intrepid.   Recovery personnel would not arrive on the scene for another thirty minutes.  In the interim, Grissom and Young had to wait inside the capsule as it bobbed up and down and up and down in the rough water.  As a result, both men came down with a touch of seasickness.

In addition, the unbearable tropical heat forced the astronauts to doff their spacesuits and strip to their long johns.  Inside the sealed Gemini III capsule, conditions were stifling.  But mission commander Grissom - doubtless drawing on the lessons of his near-drowning - flat-out refused to open the hatch until the recovery crews had fitted a flotation collar around the capsule.  When Grissom and Young were winched aboard a recovery helicopter, they were clad only in their underwear.

So that the astronauts would not lose their dignity in addition to their garments, Grissom and Young were issued Navy medical robes to don before they stepped out of the recovery helicopter and onto the deck of the Intrepid.

But - those slight discomforts and indignities notwithstanding - the astronauts were never in any real danger during the recovery phase.

One last note:  Grissom's whimsical act of re-naming his spacecraft the Molly Brown resulted in Gemini III being the only capsule in the series with a nickname.

 Sources:  The Gemini Missions site at http://www.nauts.com, and Life in Space, a Time/Life book
 

For the week beginning April 29, 2001

Flash’s Astronomical Fact #80

Motion pictures dealing with space travel have a lineage that reaches back to the very beginnings of filmmaking.  Long, long before the Star Wars series, long before Forbidden Planet, and even before the Flash Gordon serials, a groundbreaking science-fiction movie set the pattern for all of the cinematic space sagas to come.

The movie to which I am referring is Le Voyage dans la Lune (A Trip to the Moon) (French; 1902), the first space adventure film in motion picture history.  This 14-minute silent gem is both a cinematic classic and a technical masterpiece.

A Trip to the Moon was the brainchild of pioneering French filmmaker Georges Melies.

Melies was bitten by the filmmaking bug in the year 1895.  Before that, he was a professional stage magician. Melies applied his expertise in the arts of illusion to his new career as a cinematographer.  He specialized in trick photography, becoming renowned as a "film magician".  Throughout his early years as a filmmaker, Melies was forever experimenting with new or improved camera techniques - sometimes while right in the middle of shooting a movie!  Melies was one of the first filmmakers to shoot multiple scenes and then edit them together in chronological order so that the movie would tell a story.

A Trip to the Moon is generally considered to be Melies’ crowning achievement.  Melies not only produced and directed the film, he wrote the script, designed the sets, and designed the costumes.  He was also the star of the show (the leader of the Moon expedition was played by Melies). 

The script for A Trip to the Moon incorporates elements from both Jules Verne’s From the Earth to the Moon (1865), and H.G. Wells’ The First Men in the Moon (1901).  Rather than being a serious depiction of man’s first journey to another world, Melies' story is instead a delightfully whimsical fantasy.

I will not give away any of the plot, save to mention that this movie features one of the most memorable scenes in the entire history of motion pictures:  The artillery-shell spacecraft hitting the “Man-in-the-Moon” squarely in his eye.

With the centennial of A Trip to the Moon fast approaching, now would be an excellent time to see this incredible movie for yourself (it is available on home video), and I recommend highly that you do.  Nearly one hundred years after its debut, the eerie surrealism of A Trip to the Moon still has the power to hold audiences spellbound.

 Sources:  The A Trip to the Moon site at http://ww.geocities.com and the Georges Melies site at http://www.nwlink.com
 

For the week beginning April 22, 2001

Flash’s Astronomical Fact #79

Astronomy is the name given to the branch of science that makes inquiries into the nature and operation of the heavens.  Literally translated, “astronomy” means “the system of laws (that govern the workings) of the stars”.

Like many branches of science, astronomy has a number of sub-branches, or what are called related sciences.  Just as biology can be sub-divided into zoology (the study of animals) and botany (the study of plants), so too can astronomy be sub-divided into a number of specialized fields of investigation.

In no particular order, here are astronomy’s principal related sciences:

Astrometry, meaning “to measure the stars”, is the science of determining the locations and motions of the stars.  Astrometry is known also as positional astronomy.

Astronautics, meaning “sailing among the stars”, is the science of space travel and related space technologies.

Astrophysics is the study of physics as it applies to the stars and other heavenly bodies.  Astrophysics is concerned primarily (though not exclusively) with how stars come into being, how they generate energy, and how they change over time.

When science came to recognize that extraterrestrial life was a real possibility, a new sub-branch of astronomy arose: Astrobiology.

The term “astrobiology” is, of course, a variation on “astrophysics”.  However, the term is something of a misnomer.  Astrobiology, literally translated, means “the study of the stars’ living organisms”.  However, living organisms seldom find stars to be particularly hospitable locales.

Consequently, the term “astrobiology” is now having to compete with not one, but two, new terms.  Exobiology, meaning “the study of living organisms outside (the boundaries of the Earth)”. Xenobiology, meaning “the study of living organisms alien (to the Earth)”.  Both of the new terms are equal and interchangeable with astrobiology. But which one of the three terms ultimately will prevail remains to be seen.

Astrochemistry, another variation on astrophysics, is the study of chemistry as it applies not only to the stars, but also to other heavenly bodies and even the interstellar medium between stars.  Findings made by astrochemists often prove invaluable to both astrophysicists and astrobiologists.

Astrodynamics, another variation on astrophysics, is the study of dynamics as it applies to spacecraft.  Just as its terrestrial counterpart, aerodynamics, seeks to understand how aircraft fly through the atmosphere, astrodynamics seeks to understand how spacecraft travel through space; particularly how the gravitational attraction of massed bodies (such as the Sun and the planets), affects the motion of spacecraft.  The work of astrodynamicists often proves helpful to astronautical engineers when it comes to the design of spacecraft.

The next two related sciences - cosmogony and cosmology - have similar spellings and, therefore, are easily - and often - confused.

Cosmogony, meaning “the creation of the Universe”, is the study of how the features (stars, galaxies, etc.) of which the Universe is comprised came to be.

Cosmology, meaning “the study of the Universe”, makes inquiries into the origin and evolution of the Universe as a whole.  Another way that cosmology differs from cosmogony is that cosmology deals also with philosophical and theological issues in addition to scientific ones.  Cosmologists maintain a strict wall of separation between the physical and the metaphysical.  But investigate the metaphysical they will.

Ethnoastronomy is concerned with skylore.  It is the study of how astronomy figures into the traditions, legends, and mythology of various ethnic groups.

Uranography, meaning “to draw the heavens”, is the art and science of mapping and charting the Universe.  It is the astronomical analog of cartography, the art and science of mapping and charting the Earth.  The term uranography comes from Uranus, who - in classical mythology - was the heavens personified.

Bioastronomy only recently has come on the scene.  Bioastronomy differs from astrobiology in that bioastronomy is concerned solely with the search for extraterrestrial intelligence.

The last sub-branch of astronomy that I will describe herein is astrology.  Astrology means “the study of the stars”, but the study is by no means a scientific one.  Astrology is a pseudo-science (that is, a false science).

All that I will say on the subject in this essay is that astrology is predicated on the mistaken belief that the relative positions of the stars and planets have an effect on human affairs.

 Sources:  The Sky Sciences site at http://www.factmonster.com, the Cosmology/Cosmogony site at http://zebu.uoregon.edu, the Astrodynamics/Astronautics site at http:///www.geocities.com/ResearchTriangle/Facility/2435, the Bioastronomy site at http://www.seti-inst.edu, and Webster’s New World Dictionary
 

For the week beginning April 15, 2001

Flash’s Astronomical Fact #78

Sometimes, heavenly bodies that appear to be dull and uninteresting when viewed with the unaided eye become dazzling and awe-inspiring when viewed through a telescope.

Case in point:  Deep-sky object NGC 4755, the Kappa Crucis cluster.

The southern constellation Crux (The (Southern) Cross) is the smallest of all of the eighty-eight officially recognized constellations.  European explorers were awed by its four brightest stars, which formed the unmistakable shape of a Latin (Christian) cross. The rest of the tiny constellation was, however, spectacularly unspectacular.

Near Crux’s second brightest star (Beta Crucis) lies a faint object that appeared to be the constellation’s tenth brightest star.  It was, therefore, named Kappa Crucis (beta being the second letter in the Greek alphabet, kappa the tenth).  But, initially, very little was noted about Kappa Crucis beyond its existence.

However, when astronomer Abbe Lacaille viewed Kappa Crucis through his telescope during his 1751-52 visit to South Africa, he saw its true nature in all its glory.  Kappa Crucis, as it turned out, was not a single star, but in fact a star cluster.

The Kappa Crucis cluster is classified as an open cluster, meaning that its stars are fairly well dispersed. The Kappa Crucis cluster consists of approximately 100 stars, some of them of the supergiant class.  Though the cluster’s supergiant stars shine more brightly than 100,000 Suns, the Kappa Crucis cluster still looks faint because it is very far away (6800 – 7800 light years).  As stars go, those of the Kappa Crucis cluster are very young, perhaps as little as 7.1 million years old.  This in turn makes the Kappa Crucis cluster one of the youngest of all known star clusters.

One of the central stars of the Kappa Crucis cluster is a red supergiant, surrounded by a number of blue supergiants.  To keep the star charts straight, it was decided that the single red supergiant would be designated as Kappa Crucis, with the surrounding stars to be considered constituents of the Kappa Crucis cluster.

The stars of the Kappa Crucis cluster are not limited in color to red and blue.  A number of yellow and white supergiants also are part of the cluster.  This multitude of colors prompted Sir John Herschel to liken the Kappa Crucis cluster to “a casket of variously coloured precious stones”.  His description was the genesis of the star cluster’s popular name:  The Jewel Box.

The Jewel Box is universally considered to be one of the most beautiful of all heavenly bodies.  Anyone who sees it certainly will agree – but only if he sees it through a telescope.

 Sources:  The Jewel Box sites at http://antwrp.gsfc.nasa.gov, http://www.aao.gov.au, http://seds.lpl.arizona.edu, and http://www.dibonsmith.com
 

For the week beginning April 8, 2001

Flash’s Astronomical Fact #77

Here is a classic space trivia question.

Prior to the advent of the Voyager II probe and the Hubble Space Telescope, the planet Uranus had only five known moons.  The moons – Uranus’ five largest – were named (in alphabetical order) Ariel, Miranda, Oberon, Titania, and Umbriel.

Now, here is the trivia question:  Of those five moons, which one was not – I repeat, not - named for a character from the works of William Shakespeare?

Well, how about it, all you Shakespeare aficionados?  Can you tackle that question?

How about all you classical literature buffs?  Do you know the source of the name of the non-Shakespearian moon?

Okay, here are the answers:

Ariel was a mischievous airy spirit from Shakespeare’s The Tempest.

Miranda was the daughter of the magician Prospero, also from The Tempest.

Oberon was the fairy king in Shakespeare’s A Midsummer Night’s Dream.

Titania was the fairy queen (and Oberon’s wife), again from A Midsummer Night’s Dream.

Umbriel was the heroine in Alexander Pope’s The Rape of the Lock.

In 1985-86, the Voyager II probe discovered ten more Uranian satellites.  They also have been named for characters from Shakespeare and Pope.

In recent years, five more confirmed moons and one suspected moon have been discovered for Uranus, bringing the total number of Uranian satellites to at least twenty, possibly twenty-one.  The five confirmed moons have been given tentative names, again from Shakespeare and Pope.  If and when the suspected moon is verified to be a Uranian satellite, it also will be given a tentative name, again from Shakespeare or Pope.

In their nomenclature, the moons of Uranus are unique.  They are the only bodies in the Solar System that are named for characters from classical literature rather than classical mythology.

 Source:  The Uranian Moons site at http://seds.lpl.arizona.edu
 

For the week beginning April 1, 2001

Flash’s Astronomical Fact #76

Today is April 1, 2001.

In the United States and many European nations, the first day of April is called April Fools (or All Fools) Day.  On April Fools Day, pranksters come out in force, loaded to bear with all manner of tricks intended to test the gullibility of the unwary.

April Fools Day came into being several centuries ago; and there is some dispute as to its exact origin.  With that caveat, what follows is the consensus opinion as to how April Fools Day came to be part of Western secular culture.  It has to do with calendars.

The Julian calendar (named for Julius Caeser) had been in use since the days of ancient Rome and was the standard datekeeper throughout most of Europe.  Though the Julian calendar provided for a Leap Day, it still was a tiny bit out of sync with the solar cycle.  Each year, the calendar lost about 11 minutes.  By the time the 1500s rolled around, all of those “tiny bits” had accumulated to the point that the Julian calendar was ten days behind the seasons.

Obviously, the calendar needed some refinements. Pope Gregory XIII, aided by astronomer/mathematician Father Christopher Clavius, S.J., modified the old Julian calendar so as to keep it in sync with the seasons.  The new Gregorian calendar meant, among other things, that New Year’s Day would now be celebrated on January 1, rather than at the time of the March Equinox, as was then the custom.

Though the new calendar was a marked improvement over the old, Gregory XIII did not have the authority to compel the nations of Europe to use it.  That authority rested with each nation’s sovereign leader (i.e., the king or queen of that nation).

When French King Charles IX gave the Gregorian calendar his blessing, it meant that - henceforth - France would recognize January 1 as New Year’s Day.  And that single change would prove to be the genesis of April Fools Day.

As I said, most of the nations of Europe welcomed the New Year on or about the first day of Spring.  But in Renaissance France, New Year festivities were a week-long affair, beginning on March 25 and culminating on April 1.

In 16th century Europe, communications were slow.  Months, even years, passed before some French folk heard of their sovereign’s decree regarding the calendar change.  Others heard of it almost immediately, but stubbornly refused to recognize January 1 as New Year’s Day because they did not want to abandon their traditional week-long celebration.

And so, for this reason or that reason, some people continued to celebrate the New Year as they had before - right through April 1.  The rest of the population looked upon them with contempt for their non-conformity.  Anyone caught celebrating the New Year on April 1 was called, with derisive intent, a “Poisson d’Avril”, which is French for “April Fish”.  How “fish” came to be used as a pejorative description for the April celebrants is unclear.  It may have had something to do with the fact that the March Equinox coincided with the night sky appearance of the constellation Pisces (the Fishes).

In any case, it became popular to subject to ridicule those who still celebrated the coming of the New Year in the traditional manner.  The ridicule was effected by means of pranks.  The very first April Fish prank was to tag April 1 celebrants as such by surreptitiously pasting paper fish onto the backs of their shirts, sort of a 16th century version of the “Kick Me” sign.  As you might imagine, the practitioners soon were pasting paper fish onto the backs of anyone they wished to antagonize, regardless of when he celebrated the New Year.

Eventually, pasting paper fish onto people’s backs became passé.  Folks started using their imagination to create new kinds of pranks (Hey, Francois, your bootlace is untied).  Another popular prank was to trick April Fish into going on “fool’s errands” (Hey, Jacques, you have to get home.  Your house is on fire.).  When the mark came to realize that he had been had, the trickster would shout “April Fish!” at his hapless victim.

In the years that followed, the custom of playing pranks on April 1 spread from France to the rest of continental Europe to the British Isles and, ultimately, to America.  Along the way, the enigmatic “April Fish” gave way to the more natural “April Fool”.

Bottom line:  When you sing “Auld Lang Syne”, make sure that you are doing so on January 1.  Do it three months hence, and you truly will be an “April Fool”.

 Source:  The April Fools Day site at http://wilstar.com
 

For the week beginning March 25, 2001

Flash’s Astronomical Fact #75

When the Soviets put the first man (Yuri Gagarin) into space, they needed a name for this new kind of explorer. It was decided that Soviet space explorers would be called ‘’cosmonauts”.

The United States also wanted to put men into space; but wanted also for American space explorers to go by a different name, so as to distinguish ours from theirs.  American space explorers were dubbed “astronauts”.

Cosmonauts and astronauts are spearheading man’s leap into the future; yet, the roots of their names reach back to the earliest days of seafaring.

The root common to both words is “naut”. “Naut” comes from the Greek word nautes, meaning “sailor”. Though originally intended to refer just to a sea-going traveler, “naut” has come to refer to any traveler, whatever he may traverse in order to get from point A to point B.

In the late 18th century, two Frenchmen (the Montgolfier brothers) invented the hot-air balloon.  Those who went aloft in such balloons looked as though they were sailing through the sky aboard flying boats.  In short order, the French came up with an appropriate term to describe a balloon traveler.  Put the root “aero” (from the Greek word aer, meaning “air”) in front of the root “naut”, and you have an “aeronaut”, or “air sailor”.

When balloons (and later airplanes) began conveying passengers, it became necessary to distinguish those who were directing the craft from those who were just going along for the ride.  The term “aeronaut” fell largely into disuse, to be replaced by the more specific term “pilot”, referring to someone who steers a craft - any kind of craft.

But though it had become a linguistic relic, the word "aeronaut” furnished the base for the names given to space travelers.  Replace the “aero” with “cosmo” (from the Greek word cosmos, meaning “universe”), and you have a "cosmonaut" or “universe sailor”.  Replace the “aero” with “astro” (from the Greek word astron, meaning “star”), and you have an "astronaut" or “star sailor”. 

By the way, here is an interesting side note:  It was the French - with a remarkably insightful eye to the future - who coined the name for the scientific study of space travel -  "astronautics".  This was way back in the year 1927, around the time of the first serious experiments with liquid-fueled rockets.

Nowadays, space explorers hail from a number of countries.  Almost all non-American/non-Russian space explorers call themselves astronauts.  The term has come to refer to any space explorer, regardless of his nationality.

But Russian space explorers - doubtless filled with fond memories of the glory days of the old Soviet space program - still call themselves cosmonauts; and probably always will.  Even in the new Russian Republic, old traditions die hard.

 Source:  Webster’s New World Dictionary
 

For the week beginning March 18, 2001

Flash’s Astronomical Fact #74

The previous edition of Flash’s Astronomical Facts examined two of the Milky Way Galaxy’s satellite galaxies:  The Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC).

The Large Magellanic Cloud made headlines in the year 1987.  On February 24 of that year, a new supernova burst onto the scene as one of the stars in the LMC exploded.  And this was no ordinary supernova.  For the first time since the year 1604, a supernova in the Earth’s night sky was bright enough to be seen with the unaided eye.  Moreover, it was the first visible supernova to occur since the invention of the telescope (1608).

The supernova was designated SN 1987A. SN 1987A was first observed telescopically by Ian Shelton of the University of Toronto, who at the time was working out of the Las Campanas Observatory in Chile (SN 1987A was not visible from North America).  SN 1987A occurred near a region of the LMC known as the Tarantula Nebula, which lies some 170,000 light years away.  The progenitor star (that is, the star that became SN 1987A) had been designated previously Sanduleak –69 202.

Astronomers classified SN 1987A as a Type II Supernova.  A full discussion of supernova classifications is beyond the scope of this essay.  But here is what is interesting.  Before SN 1987A, the only stars believed capable of becoming Type II Supernovas were red supergiants.  But Sanduleak –69 202 was a blue supergiant.  Sanduleak –69 202 was eighteen times as massive as our Sun; but, at the same time, it was also twenty times smaller than a typical red supergiant.

For a time, astronomers were puzzled as to how a blue supergiant could exhibit the characteristics of a Type II Supernova.  They had to deal also with another perplexing fact.  SN 1987A was not nearly as bright as a Type II Supernova should have been.

Scientists eventually came up with a theory to explain the anomalies.  They postulated that older blue supergiant stars such as Sanduleak –69 202 could have higher temperatures than younger blue supergiants of similar size.  Accordingly, Supernova 1987A did not appear as bright as it should have for two reasons:  First, Sanduleak –69 202, as noted above, was much smaller than a typical red supergiant, the usual progenitor of a Type II Supernova.  Second, as an older and hotter blue supergiant, Sanduleak –69 202 radiated most of its energy in the form of invisible ultraviolet (UV) rays rather than visible light rays.

When Sanduleak –69 202 went nova, SN 1987A continued to radiate energy in the form of invisible UV rays.  Only after a period of expansion and cooling did SN 1987A begin to emit its energy as waves of visible light.  But, by that point in the expansion process, most of the energy already had been expended in the form of invisible UV rays.

In brief, though the progenitor star was energetic enough to explode into a Type II Supernova, SN 1987A did not display most of its expended energy in a form of light that was visible to the eye.

SN 1987A no longer is visible to the unaided eye, but still continues to be studied by ground-based optical and radio telescopes, as well as by the orbiting Hubble Space Telescope (HST).

In fact, the HST took a somewhat baffling picture of SN 1987A in 1994.  The picture showed two glowing rings of gas in the vicinity of SN 1987A, each with a diameter (in 1994) of some 1.3 light-years.  Astronomers believe that the twin rings are associated with SN 1987A, because they are mirror images of each other and situated on either side of the supernova.  However, the exact nature of these rings has yet to be explained fully.  Once again, SN 1987A has presented scientists with a mystery; only this mystery has yet to be solved conclusively. Stay tuned.

 Sources:  The Supernova 1987A sites at http://zebu.uoregon.edu, http://www.phy.ustu.edu, http://astrosun.tm.cornell.edu, and http://www.onlineastronomy.com
 

For the week beginning March 11, 2001

Flash’s Astronomical Fact #73

Our Milky Way Galaxy is surrounded by a number of smaller galaxies.  These smaller galaxies are gravitationally bound to the Milky Way Galaxy and move with it through space.  They sometimes are referred to as "satellite galaxies" because they orbit the Milky Way Galaxy just as satellites orbit planets.

The two biggest of these satellite galaxies are also two of the closest.  They are the Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC).

Both galaxies are so named because they were observed by Ferdinand Magellan and his crew during history’s first around-the-world voyage.  Rounding the tip of South America meant traveling farther into the southern latitudes than any European explorer had ever traveled before.  Thus, Magellan and his crew were the first to see what no European explorer had ever seen before.

Though both the LMC and the SMC are galaxies, they both are called “clouds” because of their wispy outlines.  Both are classified as irregular galaxies because each lacks for a regular structure.  Both are visible to the unaided eye.  Both lie close to the glowing band of the Milky Way. 

In fact, both the LMC and the SMC once were thought to be offshoots of the Milky Way.  However, this is not the case.  The LMC and the SMC simply lie along nearly the same line of sight as the Milky Way.  Both the LMC and the SMC are situated far beyond the confines of the Milky Way Galaxy.

The LMC and the SMC lie close to each other on the sky’s dome, a mere 22 degrees apart.  Less than 100,000 light-years separate the LMC from the SMC.  The LMC is found in the vicinity of the constellation Dorado (The Goldfish).  The SMC lies in the region of the constellation Tucana (The Toucan).

The LMC, as you might surmise, got its name because it appears to be bigger than the SMC.  And this is not due simply to the fact that the LMC is situated closer to the Milky Way Galaxy than the SMC.  The LMC really is larger – nearly four times larger - than the SMC.

Here are the numbers:  The LMC lies about 163,000 – 196,000 light-years from the Earth (by comparison, our own Milky Way Galaxy has a diameter of 100,000 light-years).  The LMC covers about five degrees of the sky and contains an estimated fifteen billion stars.

The SMC, by comparison, lies about 196,000 – 228,000 light-years from the Earth.  The SMC covers about two degrees of the sky and contains about five billion stars.

The LMC caused quite a stir in the year 1987.  We will discuss that in the next edition of Flash’s Astronomical Facts.

 Sources:  The Magellanic Cloud sites at http://www.britannica.com and http://www.il-st-acad-sci.org, and Galaxies by Timothy Ferris
 

For the week beginning March 4, 2001

Flash’s Astronomical Fact #72

Dealing with numbers sometimes can be difficult - especially when the numbers with which you are dealing are incomprehensibly large (a not uncommon occurrence in the study of astronomy).

Using standard units of measure, such as kilometers or miles, I easily could tell you how large a heavenly body is or what distance separates it from another heavenly body.  It would be simply a matter of obtaining the figures from the appropriate reference work.

But what would those figures mean?  More to the point, what would those figures mean to you?

Take, for instance, the question, “How big is the Sun?”

Per my reference sources, the Sun's diameter is about 1,392,400 km (865,400 miles).

That is all fine and well.  But how can the figure alone give you a true appreciation for the Sun’s immensity? It is, after all, nothing more than a number.  A fairly large number to be sure.  But a number nevertheless.

Thankfully, there is a way to give figures real meaning:  Make comparisons.  That is, instead of looking at one number in the absolute, look at two or more in the relative.

Here is an example of what I mean.  We already have the figure for the Sun's diameter.  Now, obtain the figure for the Earth's diameter.  Again, per my reference sources, the Earth’s diameter is 12,758 km (7,929 miles).

Now, compare the figures, and what does it mean?

Among other things, it means this:  If you were to run the numbers, you would find that the Sun, if it were hollow, could contain over one million planet Earths!

Yeah, wow.  That gives you a bit of perspective on the matter, does it not?

Or, consider these figures:  The mean distance from the Earth to the Moon is about 384,400 km (238,900 miles).  Which means that the Moon's orbital diameter is twice that, or about 768,800 km (477,800 miles).  Now, compare the figure for the Moon's orbital diameter to the figure for the diameter of the Sun, and what does it mean? 

Among other things, it means this: If the Sun were hollow and the Earth placed at the Sun’s center, the Sun could contain the entire Earth-Moon system – with plenty of room to spare!

Yeah, wow again.

So, as you study astronomy, look around for other comparisons.  It is comparisons that give figures meaning.

 Sources:  Time Almanac 2001 and the Moon site at http://seds.lpl.arizona.edu
 

For the week beginning February 25, 2001

Flash’s Astronomical Fact #71

What follows is the second of an occasional series about flags with stars.

The stars in the night sky exist in the realm of heaven.  They are within our sight, yet beyond our reach.  And certainly, they do seem to be free.  Small wonder then that stars have long symbolized faith, hope, and liberty in many cultures.  Small wonder also that stars adorn many national and state banners. 

With Texas Independence Day coming up on March 2, now is a good time to examine one of the most famous of all starred flags:  The flag of the state of Texas.

The present-day flag of the state of Texas - called the Lone Star flag - consists of a broad vertical stripe of blue on the left, and two broad horizontal stripes (white on top, red below) on the right.  The blue stripe sports a single large, white, five-pointed star.  The star that adorns the Texas flag, like the stars on the American flag, is in the shape of a regular pentagram and oriented so that one point faces upwards.

You may know that the flags of six different nations have flown over Texas at various times in its history.  You may know also that Texas came into being by revolting from Mexico, and - as is the case in most revolutions - the rebels fought under a variety of battle flags. 

However, we will not be examining each and every flag, famous or obscure, ever to fly over Texas.  The sole topic of this essay is the Texas flag. 

Please keep in mind that I am going to be relating events that occurred over 150 years ago.  Many official records have been lost, and many accounts may be more legend than fact.  With those caveats, here is the story...

We begin in the year 1835.  Having abrograted the Mexican Constitution of 1824, Mexican president Antonio Lopez de Santa Anna's rule was becoming increasingly tyrannical.  Relations between the national government of Mexico and its northern region of Texas were beginning to deteriorate.  Skirmishes between the Mexican army and settlers from the United States (called Texians) were becoming increasingly frequent.  Though Texas would not formally declare independence from Mexico until March 2, 1836, the Texians already were in a civil war - in fact if not in name.

But it was hard for the Texians to get organized, as they were not exactly of one mind when it came to their political beliefs.  About the only thing holding them together was their mutual dislike of the rule of Santa Anna.  But even that thread (at least in the early going) was tenuous at best.  So strong were the ideological agendas fracturing the Texians that many factions designed and flew their own flags in support of their own causes.

The most famous of these War for Texas Independence era flags was a variation on the flag of Mexico.  The basic green, white, and red tricolor was retained, but the great seal of Mexico - the “eagle and serpent” insignia - in the middle (white) stripe was replaced by the number “1824”, written in large black numerals. The “1824” referred to the Mexican Constitution of 1824.  The Texians' specific grievance against Santa Anna was his failure to honor certain rights that the Texians asserted were clearly protected by the 1824 Constitution. The “1824” flag, therefore, was the Texians’ way of saying to Santa Anna, “Had you respected our rights under the Constitution of 1824, we would not now be rebelling.”  Or, to put it in simpler language, “This is all your fault!”  If any flag actually flew over the Alamo during the famous siege of 1836, it would have been this one.

As I said, the rebels fought under a number of battle flags during the War for Texas Independence.  Because the rebelling Texians had roots in the United States, it should come as no surprise that many of these battle flags sported the same red, white, and blue colors and five-pointed stars of the United States flag.  One battle flag in particular bore an uncanny resemblance to the Lone Star flag.  It was designed by Sarah Dodson for her husband’s company of Harrisburg, Kentucky volunteers.  It consisted of a blue, white and red tricolor, indistinguishable from the present-day flag of France save for the presence of a single large, white, five-pointed star in the blue stripe.  If the white and red stripes could have been rotated ninety degrees to the right, the Sarah Dodson flag would have looked exactly like the present-day flag of Texas! 

After the fall of the Alamo on March 6, 1836, the Texians finally got their act together.  On April 21, 1836, the Texians defeated the Mexican army at the Battle of San Jacinto.  Santa Anna was captured and impelled to sign an order evacuating his troops.  The northern region had been effectively ceded.  A new nation, the Republic of Texas, was born.

The now fully independent Texans understandably wanted a flag for their new republic that was uniquely their own. A number of people submitted suggestions for the design of the new flag, some of them variations on the numerous battle flags under which the War for Independence had been fought, although we will not examine these in detail.

The first official flag of the Republic of Texas was the David G. Burnet flag.  It consisted of a blue field adorned with a single gold star.  It was adopted on December 10, 1836.

A little over two years later, on January 24, 1839, the Lone Star flag, the flag still in use today, became the official banner of the Republic of Texas.  Although the designer of the flag is not known with certainty, it is believed that Senator William Wharton, who introduced the bill that made the Lone Star flag the official banner, was also the designer of same. 

As Texas was an independent republic for the first few years of its existence (1836-1845), the flag of Texas has the distinction of having served as the official banner for both a country and a state.

It is also worth noting that it was the flag that gave Texas its famous sobriquet:  “The Lone Star State”.  This is the only case where a state got its nickname from its flag rather than from its people (Indiana - Hoosier State), ideals (Wyoming  – Equality State), or natural wonders (Washington – Evergreen State). 

The Texas flag holds one more distinction.  It is, quite probably, the state flag most recognizable by all Americans, even those who do not live in Texas.  Residents of other states, some of whom would have difficulty recognizing on sight or describing from memory their own state flag, can identify easily the bright hues, clean lines, and bold design of the flag of the Lone Star State.

 Sources:  Texas Monthly magazine (May, 1998), The Texas flag site at http://www.lsjunction.com, the Flags of the World site at http://www.ace.unsw.edu.au, The Battle of San Jacinto site at http://www.tamu.edu, and the Texas history sites at http://www.texasalmanac.com, http://www.pinette.net, and http://encarta.msn.com
 

For the week beginning February 18, 2001

Flash’s Astronomical Fact #70

Space vehicles, orbiting satellites, and deep-space probes face a variety of dangers in the so-called “void” of outer space.  These dangers include (but are not limited to) solar heat, atomic particles, micrometeorites, cosmic rays, and even man-made orbiting debris.

What effects would these hazards have on materials and systems deployed in space for many years or decades?  And how could the effects be determined and quantified?

Obviously, the only way to find out what effects long-term exposure to space has on materials and systems is to send those materials and systems into space and expose them long-term.

Thus was born the concept for the Long Duration Exposure Facility (LDEF).

The LDEF was a satellite some ten meters (thirty feet) long and four and a quarter meters (fourteen feet) in diameter. It weighed about 9,750 kilos (21,500 pounds) fully loaded.  It remains one of the largest and heaviest payloads ever deployed or retrieved by Space Shuttle.

The LDEF looked something like a fourteen-faceted crystal floating in space.  It had twelve sides along its long axis plus two flat ends.  Seventy-two experiment trays were fitted along the long axis, six trays on each of the twelve sides.  Eight additional trays were placed on one end and six on the other, for a grand total of eighty-six trays.

Fifty-seven different experiments were allocated among the eighty-six trays.  The experiments consisted mostly of materials or system components to be exposed to the space environment.  Some 200 investigators prepared the experiment trays.  They represented thirty-three private companies, twenty-one universities, nine Department of Defense concerns, seven NASA centers, and eight foreign nations.

Space Shuttle Challenger deployed the LDEF on April 7, 1984.  It was placed in a circular orbit some 400 kilometers (275 nautical miles) in height and at an orbital inclination of 28.4 degrees.  The facility was deployed without any propulsion systems, lest the experiments be subjected to acceleration forces or contaminated by exhaust fumes from jet firings.  Nevertheless, through the clever manipulation of gravity gradients and inertial forces, the LDEF orbited the Earth with three-axis stability.  That is, it maintained the same attitude relative to our planet for the entirety of its mission.  One of the rows on the long axis (Row 3) faced continuously the direction of orbit.  The row opposite (Row 9) faced continuously the direction opposite.  The end with six experiment trays faced continuously the Earth, while the end with eight experiment trays faced continuously open space.

The LDEF exposed to the hazards of space over 10,000 different substances, such as metals, polymers, ceramics, composite materials, fibers, paints, sealants, adhesives, and lubricants.

The LDEF originally was scheduled to remain in orbit for only about one year.  But delays in the Space Shuttle program had created backlogs that pushed the scheduled retrieval date to late 1986.  However, in the wake of the Challenger disaster of January 28, 1986, the entire Space Shuttle program was suspended and the fleet grounded.  As a consequence, the mission of the LDEF was extended indefinitely.

Around about late 1988, solar activity was approaching its maximum.  The increase in solar activity had created atmospheric drag that in turn had caused the facility’s orbit to decay.  The race was on to retrieve the facility before it fell to Earth.

After many months of delays, the LDEF finally was retrieved by Space Shuttle Columbia on January 12, 1990.  The LDEF had been in space for five years and nine months, and had completed 32,422 orbits of the Earth.  The retrieval occurred none to soon.  The facility had dropped to an orbital height of 286 kilometers (179 nautical miles) and was only a month or so away from re-entering the Earth’s atmosphere.

After its return to Earth, the LDEF experiment trays were deintegrated (removed) from the satellite and returned to the corporations and universities that had prepared them.  The trays were then subjected to extensive scientific evaluation, quantifying everything from physical deterioration to chemical decomposition.  Some materials had disintegrated completely from exposure to the space environment, while others had held up remarkably well.

The LDEF provided valuable information regarding the effects of long-term space exposure on various materials. Among other things, it was found that Dacron fibers disintegrate under exposure to atomic oxygen, a highly reactive form of oxygen found in Low Earth Orbit.  As a result, the use of Dacron to sew together the multi-layer insulation (MLI) mats used in space vehicles has been discontinued.

 Sources:  The Long Duration Exposure Facility sites at http://www.ksc.nasa.gov and http://seats-www.larc.nasa.gov
 

For the week beginning February 11, 2001

Flash’s Astronomical Fact #69

In the previous edition of Flash’s Astronomical Facts, I told you how a Space Shuttle Launch Vehicle is assembled. In this edition, I will relate how certain failures in that assembly contributed to the Challenger disaster of 1986.

To review in brief:  The Launch Vehicle consists of four separate components:  The Orbiter itself; a large External Tank that holds two separate internal tanks of liquid fuel and liquid oxidizer; and twin Solid Rocket Boosters (SRBs).  The SRBs are constructed from a number of cylindrical sections, set one atop the other and bolted together.  To prevent hot gases from leaking around the joints, the sections are sealed (among other ways) by means of two encircling gaskets of rubberized material.  These gaskets are called O-rings.

Under conditions of extreme cold, the O-rings become too inflexible to perform their task of sealing the joints between sections.  When launch directors cleared the Challenger for liftoff, the outside temperature was 36 degrees F.  Engineering specifications state that the O-rings become unreliable if the temperature drops below 51 degrees F.

Here, in brief, is the sequence of events that culminated in the loss of the Space Shuttle and her crew of seven: 

The Challenger lifted off from Kennedy Space Center's Pad 39-B at 11:38 a.m. EST on January 28, 1986.

Trouble began almost from the very moment of launch.  Videotapes reviewed after the disaster showed an anomalous puff of blackish smoke emerging from the right SRB just one second after liftoff.  The smoke, indicative of O-ring failure, was leaking from an aft field joint at a point facing the External Tank.  Engineers later speculated that the leak had then become temporarily sealed by solid fuel debris.  Otherwise, the Challenger disaster might have occurred mere seconds after launch, and at a much lower altitude. 

58 seconds after liftoff, as shown on enhanced videotape footage, the first flicker of a jet of hot gas was seen to emerge from the right Solid Rocket Booster at the point of smoke leakage.  Like an acetylene torch, the jet of leaking gas began to cut into the bottom of the External Tank, where the lower internal tank of liquid hydrogen was located.

59 seconds into the launch, the jet was now well-defined and continuous, visible even in un-enhanced videotape footage.

64 seconds after liftoff, the liquid hydrogen tank was breached.  Orange flames could be seen between the External Tank and the belly of the Orbiter.  At this point, the Launch Vehicle had suffered considerable structural damage, setting up a vicious cycle.  The more structural damage the Launch Vehicle suffered, the more aerodynamically unstable it became.  The more aerodynamically unstable it became, the more structural damage it suffered.

72 seconds into the launch, the hydrogen tank suffered a major breach, causing the pressurized liquid hydrogen to burst forth out of the bottom of the tank in a massive rush.  This action created an opposite reaction, sending the hydrogen tank thrusting upwards.  It crashed into the bottom of the upper internal tank of liquid oxygen.  Meanwhile, the right SRB had torn loose from the lower strut connecting it to the External Tank.  The right SRB swiveled inwards on the upper connecting strut, sending its nose crashing into the External Tank at a point where the liquid oxygen was stored.  Thus, almost simultaneously, the oxygen tank was rammed at two points.  The force of the impacts breached the liquid oxygen tank.

73 seconds after liftoff, with the fuel and oxidizer tanks both now breached, the liquid hydrogen and liquid oxygen vaporized and combined almost instantly to form a highly explosive mixture.  The mixture detonated, blasting both the Space Shuttle and the External Tank to bits.  The twin Solid Rocket Boosters, now disengaged from the External Tank, spiraled away wildly.  Ground controllers destroyed the SRBs by remote control 30 seconds later.

Spectators who had gathered to observe the launch – including members of the astronauts’ families - could only watch in disbelief as showers of debris and tendrils of smoke descended to Earth.

And so, a billion-dollar spacecraft was lost as the consequence of the failure of $900 worth of rubber gaskets.

But how on Earth could this happen?  How could the most advanced flying machine ever built, the cumulative work of the world’s top aerospace engineers, fail so utterly?  A thorough discussion of the details of the Challenger disaster is beyond the scope of this webpage.  However, whole volumes have been written on the subject and are worth reading.  They tell a disturbing story of how mechanical failures and human failings combined to create a disaster waiting to happen.  And one that must not happen again.

 Sources:  The Challenger Disaster sites at http://ww.jlhs.nhusd.k12.ca.us and http://www.ksc.nasa.gov
 

For the week beginning February 4, 2001

Flash’s Astronomical Fact #68

In the previous edition of Flash’s Astronomical Facts, I recounted briefly the Challenger disaster of January 28, 1986.  Some 73 seconds after launch, a tremendous explosion destroyed the Space Shuttle, resulting in the deaths of the seven astronauts aboard her.  As the craft was only about 15 kilometers (9 miles) above the Earth at the time of the explosion, spectators on the ground as well as millions of television viewers could see with their own eyes that something had gone horribly wrong.

On February 3, 1986, President Ronald Reagan issued an Executive Order establishing a blue ribbon commission to investigate the accident and determine what had caused the loss of the Orbiter and her crew.

To understand fully what happened, quite a bit of setup will be necessary.  In this edition, I will describe how the Space Shuttle is assembled and made ready for launch.  Next week, I will relate how certain aspects of the Challenger assembly failed, leading to the disaster.

The Space Shuttle at launch consists of four principle components.

The first component is the Space Shuttle itself, the winged vehicle with which we all are familiar.  This component is called the Orbiter.

Attached to the belly of the Orbiter is a component larger than the Space Shuttle itself.  This component is called the External Tank (ET).  Within the ET are two separate tanks.  The lower tank holds the supply of liquid hydrogen fuel.  The upper tank is filled with liquid oxygen oxidizer.

Attached to either side of the ET are the last two components, the twin Solid Rocket Boosters (SRBs).  The SRBs are about as tall as the ET, but smaller in diameter.  The SRBs are filled with a solid fuel composed primarily of ammonium perchlorate mixed with powdered aluminum.

When the Space Shuttle Orbiter, External Tank, and twin Solid Rocket Boosters are fitted together as described above, the entire assembly is called the Launch Vehicle.

In the first few minutes following liftoff, it is the twin SRBs that do most of the work.  The SRBs’ stores of solid fuel provide enough thrust to lift the craft to the upper reaches of the Earth’s atmosphere.  At a point when their stores of solid fuel are nearly exhausted, the SRBs are separated from the External Tank by means of explosive bolts.  After that, the craft continues its ascent on liquid stores alone.  When the supplies of liquid fuel and liquid oxidizer are almost depleted, the ET is separated from the Orbiter.  The Space Shuttle then proceeds with the remainder of its mission.

At least, that is ideally how things should go.

Now, let us examine in detail the structure of an SRB.

Although it may appear that the SRBs are single units, they consist actually of a number of cylindrical sections set one atop the other.  The sections are joined together by means of what are called tang and clevis joints.  That is, if you were to take a cross section of a cylinder, you would see that the bottom rim is shaped like an “I”.  That is the tang.  The top rim is shaped like a “U”.  That is the clevis.  A tang and clevis joint achieves closure by dropping the “I” into the “U”.  A number of transverse bolts are then fitted through the tang and clevis to hold the sections together.

Though the sections are engineered to fit one into the other, they still will be subject to terrific amounts of heat and vibration during the times that the SRBs are expending their stores of solid fuel.  Under such forces, the sections could expand and buckle, allowing hot gases to leak around the joints.

To prevent hot gases from escaping, the sections are sealed by filling the clevis with a pliable fireproof putty and fitting it with two encircling gaskets of rubberized material.  These flexible gaskets, called O-rings, expand or contact with the movements of the cylindrical sections.  Thus, the joints between sections remain airtight.

At least, that is ideally how it should work.

The O-rings have a weakness.  Exposure to cold makes the rubberized material less flexible, and therefore less able to fulfill its task of sealing the cylindrical sections.  In fact, the engineering specifications state that the O-rings become unreliable if the temperature drops below 51 degrees F.

Temperature at launch time on that fateful day:
36 degrees F.

We will examine how the failure of the O-rings led to the Challenger disaster in the next edition of Flash’s Astronomical Facts.

 Sources:  The Challenger Disaster sites at http://ww.jlhs.nhusd.k12.ca.us and http://www.ksc.nasa.gov
 

For the week beginning January 28, 2001

Flash’s Astronomical Fact #67

This is January 28, 2001.

Exactly fifteen years ago today, lives were shattered and the U.S. space effort was suspended as the consequence of a terrible disaster.

On January 28, 1986, Space Shuttle Challenger lifted off from Florida’s Kennedy Space Center for a planned six-day voyage.  The mission, designated Flight 51-L, was to be the twenty-fifth Space Shuttle flight and the tenth for the orbiter Challenger.

But, a little under one minute after liftoff, a jet of hot gas burst forth from one of the two Solid Rocket Boosters. Like an acetylene torch, the fiery jet cut into the large External Tank, which was filled with both liquid hydrogen and liquid oxygen.  As the Challenger approached an altitude of nine miles, the liquid hydrogen tank was breached.  The leaking hydrogen vaporized, caught fire, and enveloped the entire Launch Vehicle in orange flames.  Seconds later, the liquid oxygen tank also was breached.  A tremendous explosion followed, blasting both the External Tank and the Space Shuttle orbiter to bits.  The twin Solid Rocket Boosters, still expending their fuel, spiraled away, out of control.  The debris fell into the Atlantic Ocean near the Florida coast.

As a consequence of the disaster, the entire orbiter fleet was grounded pending investigation.  Space Shuttle flights would not resume until thirty-two months later.

But it was the human toll that was most tragic.  The Challenger’s crew of seven was killed, the greatest loss of life in a single incident in the history of space exploration.

So, lest we forget, those killed were:

Francis Scobee, commander
Michael Smith, pilot
Judith Resnick, mission specialist 1
Ellison Onizuka, mission specialist 2
Ronald McNair, mission specialist 3
Gregory Jarvis, payload specialist 1
Sharon Christa McAuliffe, payload specialist 2

But exactly what caused the disaster? We will explore that question in the next two editions of Flash’s Astronomical Facts.

 Sources:  The ChallengerDisaster sites at http://ww.jlhs.nhusd.k12.ca.us and http://www.ksc.nasa.gov
 

For the week beginning January 21, 2001

Flash’s Astronomical Fact #66

Quite probably you have had occasion to see a ring around the Moon.  This ring, called a halo, is created when moonlight passes through high-altitude cirrus or cirrostratus clouds.

Cirrus and cirrostratus clouds are not composed of water vapor, but of ice crystals.  These crystals, no more than 20.5 microns in diameter, look like hexagonal (six-sided) columns.  Moonlight is refracted (bent) as it enters one facet of the crystal and is refracted a second time as it emerges out of the facet opposite. The total angle of refraction is always 22 degrees; hence, the ring around the Moon always has a radius of 22 degrees of arc.

The same kind of ice crystals can create a similar halo effect around the Sun.  Again, the angle of refraction is always 22 degrees; hence, a solar halo, like its lunar counterpart, always has a radius of 22 degrees of arc.

The presence of slightly larger ice crystals sometimes can create a larger, secondary halo, thus putting two rings around the Sun or Moon.  The secondary halo always has a radius of 46 degrees of arc.

The ring usually is bright white; but under certain conditions, the halo can exhibit rainbow colors.  In such case, the red end of the spectrum is always on the inner portion of the ring, the violet end on the outer portion.

When meteorological conditions cause the ice crystals to align themselves in special ways, some additional phenomena may be seen.  For instance, when the ice crystals line up with their long axes horizontal, a bright patch of light called a “tangent arc” may sometimes be seen along the halo, usually on the top.  At other times, you might see colored images resembling the disc of the Sun appear on the top and bottom or left and right sides of the halo.  These discs are called parhelia, known also as “sun dogs” (their lunar counterparts are called “moon dogs” or “mock moons”).  “Sun pillars” and “sun crosses” also may be seen.  By the way, be sure to wear proper eye protection when you view any solar phenomena.  At minimum, look only at the halo, and then only out of the corner of your eye.

Folklore says that the appearance of a ring around the Moon means that rain is imminent.  And there is some credence to this truism.  The cirrus or cirrostratus clouds that contain the light-bending ice crystals are indeed harbingers of rain.  An old verse from weather folklore says:  Ring around the sun, time to have some fun/Ring around the moon, rain coming soon.

The cirrus or cirrostratus clouds that create lunar halos usually lie 500 – 600 miles away.  Thus, if you see a lunar halo, and the weather front is moving towards your area at 20 miles per hour, expect rain in 25-30 hours.

Keep in mind that a ring around the Moon is, in and of itself, no guarantee of rain.  The cirrus or cirrostratus clouds must be moving towards, not away from, your area.  Moreover, local weather conditions (temperature, air pressure, etc.) must be favorable for precipitation.

That having been said, rain has followed the appearance of a lunar halo often enough to earn a place in meteorological folklore.

 Sources:  The Moon Halo sites at http://ww2010.atmos.uiuc.edu, http://encarta.msn.com, http://www.fwkc.com, http://www.itss.raytheon.com, and http://www.britannica.com, and the Weather Folklore site at http://www.iup.com
 

For the week beginning January 14, 2001

Flash’s Astronomical Fact #65

Just as the Earth and the other planets orbit the Sun, the Solar System orbits the center of our Milky Way Galaxy.

The Earth lies at a distance of 150 million kilometers (93 million miles) from the Sun.  It takes the Earth one year to complete one orbit of the Sun.  The Sun lies some 28,000 light years from the galactic center.  It takes the Solar System 220-225 million years to complete one orbit of the center of the Milky Way Galaxy.  This period is called a cosmic year.

In the 4.6 billion years since the formation of the Solar System, the Sun - and its family of planets - has orbited the center of the Milky Way Galaxy only about 20 or 21 times.  Put another way:  If you are a student in the middle of your college years, then you have - in your lifetime - completed as many orbits of the Sun as the Solar System - in its lifetime - has completed orbits of the galactic center.

 Sources:  The Milky Way Galaxy site at http://seds.lpl.arizona.edu and the Space Trivia site at http://www.absolutetrivia.com
 

For the week beginning January 7, 2001

Flash’s Astronomical Fact #64

Now that we are officially in the new millennium…

According to the United States Naval Observatory, the third millennium (2001-3000 AD) will consist of exactly 365,242 days.

Yes, that includes leap years.

 Source:  The U.S. Naval Observatory site at http://www.usno.navy.mil
 

For the week beginning December 31, 2000

Flash’s Astronomical Fact #63

Last year at this time, the year 2000 was fast approaching.  The event was deemed highly significant because - they said - not only were we about to enter a new year, but also a new millennium.

But “they” were wrong.  The year two thousand has three zeroes, granted.  But we were not about to enter a new millennium.

As I explained in Flash’s Astronomical Fact #11 (January 2, 2000), the year 2000 is NOT – I repeat – NOT the first year of the third millennium.  It is the last year of the second millennium.

How so, you ask?  It has to do with the way years are counted.  You see, though it is hard to believe, THERE IS NO YEAR ZERO!  The sequence of years goes like this:  … 3 BC, 2 BC, 1 BC, 1 AD, 2 AD, 3 AD ...

As a result, the counting begins with one, not zero.  1 was the first year of the first millennium.  1001 was the first year of the second millennium.  And 2001 will be the first year of the third millennium.  Live it, love it, learn it, get used to it.

And, as I said last year, my purpose in reporting this fact was not to be a party pooper, but just to speak a simple truth.  A falsehood popularly believed to be true is still a falsehood.

In any case, it soon will be academic.  When the last stroke of midnight tolls this evening, it will be January 1, 2001.  We will finally, actually, really-for-real have entered the third millennium.

 Source:  The millennium site at http://greenwich2000.co.uk
 

For the week beginning December 24, 2000

Flash’s Astronomical Fact #62

Civilian time divides the twenty-four hour clock into two twelve-hour periods:  The morning hours, designated as ante meridian or a.m.; and the evening hours, designated as post meridian or p.m.  The demarcation point between a.m. and p.m. is noon; and the demarcation point between p.m. and a.m. is midnight.

Now, when people speak of noon and midnight, the question always arises:  Is noon designated as a.m. or p.m.?  And what about midnight?

In common usage, noon is designated as p.m. (hence 12:00:00 p.m. noon); and midnight is designated as a.m. (hence 12:00:00 a.m. midnight).

However, neither is technically correct.

Noon and midnight do not fall into either a.m. or p.m.  Noon, in the strictest sense, exists for only an instant.  As I said, it is the demarcation point between a.m. and p.m. (with the emphasis on point).  Midnight – the demarcation point between p.m. and a.m. – likewise exists for only an instant.  Proper to say 12:00:00 n. (noon) and 12:00:00 m. (midnight)

It may seem as though I am picking nits.  But the definitions of noon and midnight will become very significant next week.  As we will see in the next edition of Flash’s Astronomical Facts.

 Source:  The Noon and Midnight site at http://www.earthandsky.org
 

For the week beginning December 17, 2000

Flash’s Astronomical Fact #61

Why do stars appear to twinkle while planets seem to shine steadily?  This is one of the most frequently asked questions in astronomy.

The reason is not hard to understand, but it will require a bit of setup to explain fully.  Just bear with me.

The stars in the night sky are very big, but lie very, very far away.  The planets, by contrast, are much smaller, but lie much, much closer.  The result is that the distant stars appear to be pinpoints of light, while the closer planets are more like dots.

The Earth’s atmosphere is turbulent.  Which is to say, the air is in constant, random motion.  Moreover, the atmosphere consists of layers of air of various temperatures and different densities.  The result is that light incoming from outer space is refracted and scattered long before it reaches our eye.

Here is the reason that stars twinkle.  Because a star appears to be a pinpoint in the night sky, it sends - for all practical purposes - a single beam of light towards us.  When that single beam hits the atmosphere, its light is refracted and scattered.  Though the light the star sends towards the Earth is a continuous beam, it is a beam that is alternately moving towards and then away from our eye.  Thus, the star seems to wax and wane every fraction of a second. Hence, to our eye, the star appears to twinkle.

It is different with the planets.  As I said, a planet appears in the night sky to be not a pinpoint, but a dot.  That larger dot sends not just one, but many beams of light towards us.  True, each and every one of those individual beams of light coming from the planet is refracted and scattered, just as is the single beam of starlight.  But, because there are many beams coming at us from across the span of the planet’s dot, only the fringe beams will be scattered away from our eye, while at the same time the bulk of the beams in between will be scattered towards it.  The result is that a large majority of the light beams from the planet are scattered towards our eye at any given fraction of a second.  Since most of the light from the planet falls on our eye continuously, the planet never seems to wax or wane.  Hence, to our eye, the planet seems to shine steadily.

With Christmastime drawing near, you can perform a simple experiment that will give you a rough idea of this concept. All that you need are a couple of strong rubber bands and a string of miniature Christmas lights that are able to be set so as to flash on and off rapidly.  Ideally, the string should have bulbs of one single color, although a multicolor strand will do the job adequately.  CAUTION:  If you are one of our younger visitors, ask an adult to help you.

Hang the string over a low tree branch or similar object.  Wait until it gets dark, then plug in the strand, setting the light controls to flash on and off rapidly.  It is best to stand back and view from a distance.

The individual bulbs flashing on and off will simulate the light from a star being scattered alternately towards and away from your eye.  The miniature bulbs, like the stars, will seem to twinkle.

Now, using the rubber bands, gather a dozen or more bulbs into a single bundle, with all of the lights pointing in one direction.

Then, look at the bundle of miniature bulbs. Do not concentrate on any one bulb within the bundle.  Look at the bundle as a whole.  At least half of the bulbs in the bundle will be on at any given time, which will simulate the light beams from a planet.  The bundle will appear to shine steadily (or at least, more steadily than any of the single bulbs nearby).

Granted, this is a crude approximation.  But it should make the concept clear.

 Source:  The “Why do Stars Twinkle while Planets Shine Steadily?” sites at http://ww.dsy.de and http://exosci.com, and the Physics FAQ site at http://www.math.ucr.edu
 

For the week beginning December 10, 2000

Flash’s Astronomical Fact #60

In ancient times, astrologers presumed that those born under the sign of the planet Jupiter would grow up to be a jolly lot, full of high spirits and good humor.  Another name for Jupiter is Jove.  This is how we got the word that describes a happy and convivial fellow - jovial!

 Source:  Webster’s New World Dictionary
 

For the week beginning December 3, 2000

Flash’s Astronomical Fact #59

What follows is the second of an occasional series about the constellations.

Most of the constellations in the night sky depict animals (both real and fanciful), scientific instruments, and the gods and heroes of classical mythology.  One notable exception is the southern hemisphere constellation Scutum Sobiescianum (pronounced “Scoot-um Soh-bee-ess-kee-ahn-um”) (The Shield of Sobieski).  Scutum is one of the few constellations that pays homage to an actual historical figure.

Here, in brief, is the history of Scutum.

Jan Sobieski (1624-1696) was the eldest son of Jakob Sobieski, the castellan of Crakow.  Jan Sobieski was a brilliant military strategist.  By 1665, he had become the field commander of the Polish army.

In Jan Sobieski’s time, the main threat to Poland (and, for that matter, all of Europe) was the Ottoman Empire. The envoys to the king of Poland had been forced to cede all of the Ukraine to the Turks.  But Jan Sobieski continued to fight to defend his native Poland.

In November of 1673, the king of Poland died.  Jan Sobieski left the front lines to present himself in Warsaw as a candidate for the throne (this kingship was an elected position).  On May 21, 1674, Jan Sobieski became King Jan III of Poland.  Then, it was back to the war. 

On March 31, 1683, King Jan III signed the Treaty of Warsaw with Emperor Leopold I.  The Treaty obligated King Jan III to defend Vienna, but also gave him the imprimatur to command the armies of Europe as a single fighting force.  On September 12, 1683, a climactic battle took place near Vienna, with Jan Sobieski taking personal charge of the Polish cavalry.  Jan Sobieski’s combined forces broke the Turkish army, and its leaders fled in panic.  The Ottoman Empire was finished in Europe.  Jan Sobieski’s victory had assured that the continent would remain Christian.

In 1690, Polish astronomer Johannes Hevelius decided to honor his countryman by creating a new constellation, Scutum Sobiescianum.  This constellation (along with Canes Venatici, Lacerta, Leo Minor, Lynx, Sextans, and Vulpecula) was incorporated into his posthumous catalogue Prodromus Astronomiae.

Hevelius was not alone when it came to creating new constellations.  Other astronomers of the era were doing the same.  Naturally, almost all of these one-man creations were relegated to history when the constellations were standardized.  But Scutum managed to become one of the eighty-eight officially recognized constellations.

How? 

Well, as they say, it is not what you know, but whom you know – and timing is everything.

Hevelius’ contemporary, John Flamsteed, was a stellar cartographer who devised a numbering system for cataloging the stars (a system still in use today).  Flamsteed gave Hevelius’ new constellations credence by accepting them into his catalogue of 1725.  When the Astronomical Congress of 1928 met to establish the official constellations, great consideration was given to Flamsteed’s catalog (Hevelius’ constellations included) because of the former’s pioneering work in astronomy.

Thus, through a series of historical coincidences, Scutum made the “final cut”.

Scutum is a small constellation (in fact, fifth smallest overall).  Its stars are relatively faint.  And the design, to be honest, is not all that impressive.  Its three brightest stars define two long lines that suggest a curved shield viewed from edge-on.  A bundle of stars behind the long lines suggest the handgrips of the shield.  As I said, not much to see from our earthly vantage point.

But, when one thinks about it, perhaps it is appropriate that the shield is aligned the way that it is.  Just as the Turks saw the original shield of Sobieski head-on, so too now will any cosmic invader view its stellar counterpart head-on.  Sobieski’s shield, thus perfectly oriented in the night sky, stands ready to defend the other constellations from whatever may befall.

 Source:  The Scutum site at http://www.dibonsmith.com and the Jan Sobieski sites at http://www.campus.northpark.edu and http://www.britannica.com and Webster's New World Dictionary
 

For the week beginning November 26, 2000

Flash’s Astronomical Fact #58

In the previous edition of Flash’s Astronomical Facts, I described the two basic kinds of star clusters.  In this edition, we will discuss the long-term destinies of each.

The stars within open clusters are widely dispersed, which means that the gravitational attractions between them are very weak. This - coupled with the fact that open clusters usually form within galaxies - means that the constituent stars of open clusters are subject to influence by a variety of internal and external forces. Over time, the individual stars may leave the collective for a number of reasons.  Stars may be pulled out of the cluster by strong gravitational bodies (such as a massive supergiant star passing nearby).  Or, interaction between two stars within the cluster may cause each to hurl the other out of the collective.  Finally, some of the stars may simply drift away.

Every time a star leaves the cluster, the system’s total gravity becomes that much weaker.  This makes it easier for the next star to leave the cluster, which in turn makes the departure following easier still.  The process accelerates until only one star remains - at which point the open cluster simply ceases to exist.  Open clusters such as the Praesepe Cluster in Cancer (The Crab) may continue as a collective for at most several hundred million years.  Relatively short on cosmic time scales.

Globular clusters, by contrast, usually form outside the main body of a galaxy.  As such, gravitational forces external to the cluster are weak, and internal forces are strong.  Globular clusters may, therefore, last considerably longer than open clusters - up to several billion years! 

As one example, the stars within globular cluster M13 in the constellation Hercules (The Legendary Strongman) are estimated to be at least 12 billion years old.  These stars have lasted as long as they have because they are among the most sedate in the universe, using their stores of hydrogen fuel at a miserly rate.  Since the stars in a globular cluster form at approximately the same time, this suggests by extension that the M13 cluster itself is nearly as old as its constituent stars.  Indeed, M13 is thought to have formed concurrent with the Milky Way Galaxy itself! 

Star charts mark the locations of most of the clusters that are visible to the unaided eye.  Through a telescope - even a backyard telescope - these clusters make for spectacular viewing.

 Sources:  The Star Cluster sites at http://www.britannica.com, http://www.kopernik.org, http://seds.lpl.arizona.edu, http://www.infoplease.lycos, the Alpha Centauri site at http://homesunrise.ch, and Galaxies by Timothy Ferris
 

For the week beginning November 19, 2000

Flash’s Astronomical Fact #57

In this edition of Flash’s Astronomical Facts, we will discuss star clusters.

Exactly as you might surmise, a star cluster is indeed an assemblage of many, many stars.  But there is much more to it than that.  To qualify as a star cluster, the stellar congregation must move through space as a unit - usually as the consequence of the stars being bound to each other by their mutual gravitational attractions.  In addition, the stars in the cluster must be determined to have had a common origin, such as having been born from the same cloud of interstellar gas.

Star clusters come in two general types, which I will describe below.  Examples of both are visible to the unaided eye and as such have been observed since ancient times.

A cluster of the first type is known as an open cluster (known formerly as a galactic cluster, although the latter term has fallen largely into disuse).  As the term suggests, an open cluster is indeed one in which there is much space between the constituent stars.  One example of an open cluster is M44 in the constellation Cancer (The Crab).  M44 is known also as the Praesepe (pronounced “Pry-suh-pay”) Cluster.  It is visible to the unaided eye only as a fuzzy patch of light; but through a telescope, the Praesepe Cluster can be seen as some 350 individual stars, 200 of which have been confirmed as being part of the cluster.  The Praesepe Cluster lies relatively close to the Earth, at some 577 light years.  It looks something like a swarm of bees buzzing around a hive, which is how it got its nickname:  The Beehive.

Open clusters suggest the existence of closed clusters, wherein the stars are packed together more tightly. Such is exactly the case, although a cluster of this second type is known by the term globular cluster.  One example of a globular cluster is M13 in the constellation Hercules (The Legendary Strongman).  Through a telescope, M13 appears to be roughly spherical in shape (hence the term, globular cluster).  Like the Beehive, M13 is visible to the unaided eye as an indistinct patch of light.  But unlike the Beehive, M13 lies much farther away - over 22,200 light years from the Earth!  You would suppose that for anything to lie so far away and yet be visible to the unaided eye, it must be gigantic.  And you would be right.  M13 consists of a central core of tightly packed stars some one hundred light years in diameter, surrounded by an outer shell of less concentrated stars that extends up to a diameter of two hundred light years.  Most of M13’s several hundred thousand constituent stars are found in the central region, which gives the stars a spacing of about one light year apart (by contrast, our nearest visible stellar neighbor is the Alpha Centauri system, some 4.3 light years in the distance).

The long-term fates of open and globular star clusters are markedly different.  We will examine that aspect in the next edition of Flash’s Astronomical Facts.

 Sources:  The Star Cluster sites at http://www.britannica.com, http://www.kopernik.org, http://seds.lpl.arizona.edu, http://www.infoplease.lycos, the Alpha Centauri site at http://homesunrise.ch, and Galaxies by Timothy Ferris
 

For the week beginning November 12, 2000

Flash’s Astronomical Fact #56

What follows is the first of an occasional series about flags with stars.

Many of the world’s national banners bear stars.  The flag of the United States of America, for example, sports fifty stars - one for each of its fifty states.  The fifty stars are arranged in the blue union in a stylized pattern intended to represent an imaginary constellation.

In fact, this is the way that stars are presented in most of the national banners that have them.  They are symbolic representations, and therefore bear little resemblance to the actual stars in the heavens.  Granted, several of the flags of southern hemisphere nations sport the Southern Cross; but even these often are stylized representations.

However, one national banner - established 111 years ago this week - has an honest-to-goodness star chart built right into it!

The flag to which I am referring is that of the nation of Brazil.

The Brazilian flag is a rectangle of green, symbolic of its lush tropical forests.  In the middle of the green rectangle is a yellow diamond, symbolic of its mineral wealth.  In the middle of the yellow diamond is a blue circle representing the globe of the Earth.  As one looks at the blue globe, one is looking down from a point high above Rio de Janeiro, Brazil’s largest city.  A white band representing the equator (again, from the point of view of an observer high above) arcs across the blue globe.  Written in large block letters within the white band are the words “ORDEM E PROGRESSO”.  “Ordem e Progresso” is Portuguese (Brazil’s official language) for “Order and Progress”, Brazil’s national motto.

When I said that the flag of Brazil has a bona fide star chart built right into it, I meant exactly that.  Within the blue globe are twenty-seven small, white, five-pointed stars, arranged to resemble the night sky over Rio de Janeiro on November 15, 1889 at 8:30 p.m., local time (that was the exact moment when the monarchy was overthrown and a federal republic established in its place.  The flag of the new Brazilian republic was established just four days later.) The stars come in five different sizes, representing their relative (not astronomical) magnitudes.

But here is where it gets interesting.  If you were to compare the arrangement of the stars within the blue globe to a star chart, you might notice that the constellations are "flopped" (that is, they are reversed, as though you were looking at them in a mirror).  Remember, you are looking down from above.  Way, way, above.  The stars in the blue globe do not appear as they would to an Earth observer looking up – but to God looking down!

The twenty-seven stars represent the twenty-six states of Brazil, plus the Federal District.  Unlike the flag of the United States, where no star represents any particular state, each of the stars in the Brazilian flag represents a particular Brazilian state or the Federal District.

But, like the flag of the United States, the Brazilian flag must add stars as new states are formed; or remove one if two states are merged into one.

However, the Brazilians have not always been diligent in making the necessary changes to their flag.  Following the 1975 merger of two states into one, the flag was never changed to conform.  For a four-year period (1975-1979), the Brazilian flag had one star too many!

 Sources:  The Brazil sites at http://totw.digibel.be and http://www.emultaeme.com and the Brazil History sites at http://www.emayzine.com and http://www.geocities.com
 

For the week beginning November 5, 2000

Flash’s Astronomical Fact #55

In this edition of Flash’s Astronomical Facts, I will tell you how the Space Shuttles got their names.

America’s first Space Shuttle was slated to be named the Constitution, in honor of the upcoming bicentennial of the United States Constitution.  But the craft was re-named the Enterprisein response to a letter-writing campaign by fans of the television series "Star Trek".  The Enterprise was used to conduct a number of atmospheric test flights between February and November of 1977.  The test vehicle is now the property of the Smithsonian Institution.

The first Space Shuttle actually to fly in space was the Columbia.  Its maiden voyage occurred on April 12, 1981.  The Space Shuttle Columbia was named after a sloop captained by American explorer Robert Gray.  On May 11, 1792, Captain Gray’s Columbia braved a sandbar at the mouth of a river in the Pacific Northwest – and discovered the Columbia River.  Columbia, of course, is derived from Christopher Columbus.  Columbia is the feminine form of America personified.

1982 was the year of America’s second Space Shuttle, the Challenger.  Challenger was named after a British Naval research vessel that explored the Pacific and Atlantic Oceans in the 1870’s.

1983 brought forth the Discovery. Discoverywas named after one of two ships commanded by British explorer James Cook.  Captain Cook’s Discovery explored the Pacific Ocean in the 1770’s.

1985 was the year of Atlantis. Atlantis was named after America’s first oceanographic research vessel.  The sea-going Atlantis, a steel-hulled ketch, was the primary research vessel of the Woods Hole Oceanographic Institute from 1930 to 1966.

The U.S. space effort was set back in the wake of the Challenger disaster of January 28, 1986.  It was not until 1991 that America once again had a four-orbiter fleet with the coming of Endeavour.  Endeavour was named after the first ship commanded by Captain James Cook.  Its maiden voyage of August 1768 took it to the South Seas to observe the planet Venus transit(that is, cross the disc of) the Sun.  Measurements of the transit gave astronomers clues as to the Earth’s distance from the Sun.

But perhaps what is most noteworthy about the voyage of the Endeavour is the fact that it was the first sailing vessel to convey scientists to the scene of discovery.  Previously, researchers had to settle for reviewing the ship’s logs and crew reports. While these documents gave them some insights, it was not the same as having a professional scientist on site.  Captain Cook’s Endeavour proved the viability of bringing scientists “along for the ride”.  The space-faring Endeavour (and the other Shuttles in the fleet) carries on this tradition by carrying aloft space scientists known as “mission specialists”.

 Source:  The Space Shuttle Names site at http://science.ksc.nasa.gov
 

For the week beginning October 29, 2000

Flash’s Astronomical Fact #54

What follows is the first of an occasional series about the constellations.

One of the things you learn in life is that there is a great deal of difference between height and stature.

Case in point:  The southern hemisphere constellation Crux (The (Southern) Cross).

Of all the constellations in the night sky, Crux is the smallest.  Sandwiched between such giant constellations as Centaurus (The Centaur) and Carina (The Keel (of Argo)), stellar cartographers could allocate only a small patch of sky to tiny Crux.

But, what the constellation lacks in size, it more than makes up for it in significance.

Though it is the smallest of all constellations, it is also one of the most distinctive.  Its four brightest stars form the unmistakable shape of a cross.  So bright are the constellation’s stars and so eye-catching its shape, Crux stands out even against the background stars of the Milky Way.

In a very real sense, Crux got its start simply by being such a standout.  Pre-Christian Greek and Roman astronomers had assigned the stars of present-day Crux to Centaurus, their stellar centaur. But sixteenth-century European astronomers, exploring the southern hemisphere, could not look at that truly remarkable cross shape and not make Crux a constellation in its own right.  So they did.

But the importance of Crux goes far beyond its being bright and distinctive.  Crux has been invaluable to southern hemisphere mariners for centuries.  Crux can help a lost traveler find the direction of true south.  The method for doing so is described below.

First, some background:  Crux is shaped like a Latin (that is, Christian) cross.  Which is to say, the crossbar (short axis) is bisected almost evenly by the upright (long axis); but the upright is bisected unevenly by the crossbar.  The “head” is short and the “foot” is long. 

At the bottom of the foot, you will find Crux’s brightest star, Acrux (Acrux is an abbreviation of the star’s scientific designation, Alpha Crucis).  Acrux’s brightness is accounted for by the fact that it is not a single star, but a system of two stars revolving around their mutual center of gravity (such a pairing of stars is called a binary system).  Acrux lies closest to the south celestial pole.

Now, to find true south by using Crux, extend the foot below Acrux for four times the length of the long axis.  Expressed another way, make the long axis five times longer than it is.

You will find no visible star at the bottom of the extended foot.  Nevertheless, this imaginary point in space stands directly above true south.  Simply drop straight down from the imaginary point to the horizon.  The point on the horizon directly beneath the imaginary point in space marks the direction of true south.

Brightness, distinctiveness, and usefulness. All of these factors combine to make Crux the most easily recognized – and well known – of all southern hemisphere constellations.  For a small constellation, it has a big impact.

And just how much impact has Crux had on the peoples, history, and culture of the southern hemisphere?  Consider this:  A schematic of the Southern Cross can be found on the flags of five southern hemisphere nations:  Australia, Brazil, New Zealand, Papua New Guinea, and Samoa.  Now, that is impact!

 Sources:  What’s What by David Fisher and Reginald Bragonier, Jr., Army Field Manual FM 21-76, Survival, Evasion, and Escape, and the Southern Cross sites at http://www.windows.umich.edu and http://www.dibonsmith.com and the Flags of the World site at http://fotw.digibel.be

The Flags of the World site is an excellent website devoted to the study of flags.  National, state, and territorial banners from around the world are displayed in full color, with descriptions and origins.  Many historical banners also are listed.  The site uses an extensive cross-indexing system for fast access to desired information.
 

For the week beginning October 22, 2000

Flash’s Astronomical Fact #53

What do the keys on a piano keyboard and the constellations in the night sky have in common? 

Give up?

There are exactly the same number of each - eighty-eight.

The next edition of Flash’s Astronomical Facts will feature the constellation Crux (The (Southern) Cross). This will be the first of an occasional series about the constellations.  Eventually, we will examine all eighty-eight constellations officially recognized by the International Astronomical Union.

 Sources:  Time Almanac 2000 and http://www.pianoworld.com
 

For the week beginning October 15, 2000

Flash’s Astronomical Fact #52

What follows is the first of an occasional series about attempts to measure the velocity of light. 

The velocity of light (designated by the letter c) is one of the most important values in the sciences of astronomy and physics.

The first serious – if ultimately futile – attempt to measure the velocity of light was undertaken by the Renaissance Man himself, Galileo Galilei (1564–1642).

In Galileo’s time, there was no value for c.  Certainly, it was known that light was faster than sound (you see the lightning before you hear the thunder); but exactly how fast, no one knew. Some suggested that light was not simply very fast, but infinitely fast.

Galileo tried to attach a number to the velocity of light, using a variation on a method that around the same period had been used to determine a rough value for the speed of sound.

Galileo ascended a hill, carrying with him a timepiece and a lantern.  An assistant, carrying only a lantern, climbed a second hill.  The peaks were a measured distance (d) apart.

When darkness fell, the experiment began.  Noting the time (t₁), Galileo opened the shutter on his lantern.  His assistant, as he previously had been instructed, opened the shutter on his lantern the instant he saw the light from Galileo’s lantern.  Galileo then recorded the time (t₂) that he saw the light from the lantern of his assistant.

The velocity of light would be, therefore, the distance traveled divided by the elapsed time:

Unfortunately, Galileo's technique, while sound in concept, failed in practice.  Human reflexes are simply too slow to measure by the above method a value as high as the velocity of light.  To give you an idea of the enormity of the problem:  If the peaks in Galileo’s experiment were 7500 meters apart, light would have needed only 50-millionths of one second to travel from the first hill to the second and back again.  50-millionths of one second is far faster than the typical human reaction time of one-tenth to one-half of one second.  Indeed, Galileo found that his assistant could react no faster when the two men were six feet apart than when they were a mile apart.  As if that were not enough, no Renaissance era clock could measure so short an interval of time as 50-millionths of one second.

About all that Galileo could conclude from his experiment was that light, if not infinitely fast, was certainly very fast.  At the very least, too fast to measure using lanterns on hilltops. No, determining a value for c would seem to require that the light be tracked over an enormously long distance; or timed by much faster (and much more accurate) timing devices; or both.

 Sources:  Understanding Physics by Isaac Asimov and A Contemporary View of Elementary Physics by Borowitz & Bornstein.
 

For the week beginning October 8, 2000

Flash’s Astronomical Fact #51

American astronaut James A. Lovell accomplished a number of “firsts” during his career in space.

On December 4, 1965, Lovell and fellow astronaut Frank Borman flew Gemini VII into an orbital rendezvous with Gemini VI (launched December 15, 1965, with astronauts Schirra and Stafford).  He thus was part of the first orbital link-up between two manned maneuverable craft.

On December 21, 1968, Lovell and fellow astronauts Frank Borman and Bill Anders set out aboard Apollo VIII on the first journey to the moon.  That meant also that Lovell and his crewmates were the first to escape the Earth’s gravitational influence, as well as the first to see the entire Earth from space.  The mission of Apollo VIII was to test lunar orbital procedures.  It circled the Moon ten times and returned safely to the Earth, exactly as intended.  This meant more firsts:  Lovell and his crewmates were the first to go into orbit around the Moon and the first to see with their own eyes the far side of the Moon.

On April 11, 1970, Lovell and fellow astronauts Fred Haise and Jack Swigert set out aboard Apollo XIII on what was intended to be the third lunar landing mission.  Finally, Lovell had a first that he could call his own.  He was the first man to make two separate journeys to the Moon.

But, as we all know, disaster struck. Three days outbound from the Earth en route to the Moon, an oxygen tank aboard the command module exploded, severely damaging Apollo XIII.  The lunar landing mission had to be aborted.  The crippled spacecraft circled the Moon and returned safely to the Earth.  But this gave Lovell another first; and one he doubtless would just as soon do without. At the conclusion of the Apollo program, Lovell became – and to this day remains – the first (and only) man to have circled the Moon twice without having set foot on it at least once.

(Before you ask:  The other multiple Moon mission men were:  David Scott (command module pilot aboard Apollo IX, walked on the Moon as commander of Apollo XV); John Young (command module pilot aboard Apollo X, walked on the Moon as commander of Apollo XVI); and Eugene Cernan (lunar module pilot aboard Apollo X, walked on the Moon as commander of Apollo XVII).)

 Sources:  Life in Space, A Time/Life book, and the James Lovell site at http://ca.yahoo.com
 

For the week beginning October 1, 2000

Flash’s Astronomical Fact #50

In the previous edition of Flash’s Astronomical Facts, I told you about the Earth’s magnetic field.  In this edition, I will tell you about the magnetic field surrounding another planet in our solar system – Jupiter.

In a nutshell, the Earth’s magnetic field is generated by the motions of its outer core’s molten iron/nickel against its inner core’s solid iron.

But Jupiter has no such interior structure.  Scientists believe that Jupiter’s core is composed of silicate materials and some iron.  Moreover, Jupiter’s rocky core is surrounded not by molten metals, but by gases such as hydrogen, helium, and methane. How then can Jupiter have a magnetic field at all – let alone one 20,000 times as powerful as the Earth’s?

Here is how.

Atmospheric pressure at Jupiter’s core is about three million times greater than atmospheric pressure at sea level on the Earth.  So great is this pressure that it overcomes the nuclear forces that ordinarily hold atoms together.  Atoms of hydrogen are – quite literally – crushed apart to form an irregular array of free protons interspersed with free electrons.  Since the electrons no longer are bound to any one particular proton, they are able to move freely through this quasi-crystalline array.  In other words, hydrogen in this state is electrically conductive, just as though it were a metal.  As a result, this form of hydrogen is called liquid metallic hydrogen. This outer shell of liquid metallic hydrogen, some 40,000 kilometers (25,000 miles) thick, is the functional equivalent of a metal core. 

Jupiter’s outer shell of liquid metallic hydrogen rotates at a speed different from the surrounding atmosphere, which creates a dynamo effect.  Electrons are induced to move through the layer of liquid metallic hydrogen, which produces a powerful electric current.  This in turn produces Jupiter’s comparably powerful magnetic field.

 Sources:  Voyage Through the Universe/The Far Planets, Voyage Through the Universe/The Third Planet, a Time-Life Book Series, and Secrets of the Universe
 

For the week beginning September 24, 2000

Flash’s Astronomical Fact #49

That the Earth is surrounded by a magnetic field is an accepted scientific fact.  That the Earth’s magnetic field is generated by dynamics far beneath the planet’s surface also is an accepted scientific fact.  But the exact nature of those dynamics is not completely understood.  Part of the problem, of course, lies in the fact that it is impossible for scientists to study by direct observation goings-on occurring so deep within the planet.

That having been said, scientists can draw certain inferences based on indirect observations.  What follows is the consensus scientific opinion as to how the Earth’s magnetic field is generated.

First, some background information: The chemical elements iron and nickel conduct easily lines of magnetic force. This is because they have a high degree of what scientists call magnetic permeability.  In layman’s terms, it means that iron and nickel make good magnets.  Hence, iron and nickel are known collectively as ferromagnetic elements (the prefix “ferro” refers to ferrum, the Latin name for iron).

The structure of the Earth’s interior is not uniform throughout, but instead is composed of a number of layers, like those of an onion.  Each layer has its own distinct chemical composition and physical characteristics. 

At the very center of the Earth is a sphere believed to be composed of pure iron.  It has a radius of about 1200 kilometers (720 miles).  Temperatures in this sphere, known as the inner core, range from approximately 4300 degrees C (7770 degrees F) at the outer edges to 5000 degrees C (9030 degrees F.) at the very center.  5000 degrees C is a temperature greater than that of the surface of the Sun!

Surrounding the inner core is a shell called the outer core.  The outer core extends some 2200 kilometers (1320 miles) beyond the limits of the inner core.  This shell is believed to be composed of iron with a small percentage of nickel, as well as trace amounts of sulphur and oxygen.  The outer core is somewhat cooler than the inner core, with temperatures ranging from 4300 degrees C (7770 degrees F) at the boundary between inner and outer cores to around 3700 degrees C (6700 degrees F) at the outer edges.

As you see, the inner and outer cores have slightly different chemical compositions.  Moreover, both exist in a state of matter different from the other.  Whereas the outer core is molten, the inner core is solid.

No doubt you are thinking, “Wait a minute.  Is that right?  How can the cooler outer core be molten while the much hotter inner core is solid?  Should not the inner core also be molten?”

So one would suppose.  But read on.

The reason that the inner core is solid is because it is under tremendous pressure due to all of the mass above it - including the mass of the outer core.  Though temperatures within the inner core are indeed greater than the melting point of iron, the immense pressure restrains the motion of the iron molecules of which the inner core is composed.  In other words, though it is hot enough to be a liquid, it cannot flow freely like a liquid.  Hence, the inner core is solid. 

The outer core, on the other hand, is not under nearly as much pressure.  It is hot enough to be a liquid andis free to flow like a liquid.  Hence, the metals in the outer core exist in a molten state.

As I said above, that portion of the outer core’s molten iron/nickel that is nearer our planet’s surface is relatively cool, while that nearer the inner core is relatively hot.  This causes the molten iron/nickel alternately to rise and sink within the outer core, in much the same way (and for the same reason) that boiling water roils in a saucepan.  These circular gyres are called convection currents. But these convection currents are not the only motions occurring within the outer core.  The outer core as a whole also moves laterally, due to the Earth’s rotation on its axis.  All of these motions together serve to create what is called the dynamo effect.  In other words, the Earth’s inner and outer cores combine to form the functional equivalent of an electric generator.  The mechanical motion of the outer core’s molten iron/nickel against the inner core’s solid iron induces electrons to move through the ferromagnetic metal.   This produces a fairly strong electric current, which in turn creates a fairly strong magnetic field.

Our planet’s magnetic field does more than just enable people to find their way in the wilderness by means of a magnetic compass.  The magnetic field also shields our planet from otherwise deadly bombardments of high-energy particles from the Sun.

Other planets in our solar system also have magnetic fields.  But some are produced in ways markedly different from the Earth’s.  We will examine one such planet in the next edition of Flash’s Astronomical Facts.

 Sources:  Voyage Through the Universe/The Third Planet, a Time-Life Book Series and the Earth’s Magnetic Field sites at http://www.siesmo.unr.edu, http://seds.lpl.arizona.edu, http://image.gsfc.nasa.gov, and http://pubs.usgs.gov
 

For the week beginning September 17, 2000

Flash’s Astronomical Fact #48

Fact 1:  The planet Neptune takes 164.79 Earth years to complete one orbit around the Sun.  Fact 2: Neptune was discovered on September 23, 1846.

Hold it.  If Neptune was discovered only 154 years ago, then the planet has yet to complete one orbit around the Sun since its discovery.  That being the case, how do astronomers know that it has an orbital period of 164.79 years?

How they know is because Neptune’s orbital period was not determined by observation (yet).  Instead, its orbital period was determined mathematically, using Kepler’s Third Law of Planetary Motion.

In a nutshell, Kepler’s Third Law of Planetary Motion states that the square of a planet’s orbital period is equal to the cube of its relative mean distance from the Sun.  Don’t panic.  Stay with me.  I’ll do the math.

The Earth’s mean distance from the Sun is about 93,000,000 miles.  Neptune’s mean distance from the Sun is about 2,798,800,000 miles.  Expressed another way, Neptune lies about 30.09 times as far away from the Sun as does the Earth.

Take the cube of 30.09 (that is, multiply 30.09 by itself three times).  30.09 x 30.09 x 30.09 = 27,243.729. Take the square root of 27,243.729, and you have 165.05.  (If you take into account the eccentricities of the planet’s elliptical orbit, you get the actual orbital period of 164.79 Earth years.)

Using Kepler’s Third Law of Planetary Motion, not only is it possible to calculate any planet’s orbital period in Earth years, you could calculate any planet’s orbital period relative to the orbital period of any other planet.  You could, for instance, determine how many Martian years it takes for Saturn to complete one orbit of the Sun, or what portion of a Jovian year it takes for Venus to go around the Sun once.  For this reason, Kepler’s Third Law of Planetary Motion is sometimes called the Harmonic Law.

Just imagine.  If a new planet were to be discovered yesterday, and its mean distance from the Sun posted to the Internet today, you could calculate that world’s approximate orbital period with relative ease, putting you on par with the world’s finest astronomers.

 Sources:  Voyage Through the Universe/Atlas, a Time/Life Book series, Cosmos by Carl Sagan, and Time Almanac 2000.
 

For the week beginning September 10, 2000

Flash’s Astronomical Fact #47

On July 21, 1961, the second manned flight in the Mercury series was launched.  The flight was successful, as was the splashdown in the Atlantic Ocean some fifteen minutes later.  But the capsule, dubbed Liberty Bell 7, had a re-designed hatch fitted with explosive bolts to afford quick exit.  Shortly after splashdown, those bolts fired prematurely, blowing the hatch before Navy recovery crews were in position.  The capsule began shipping water, and would eventually sink into the sea.  Barely escaping with his life was Liberty Bell 7’s commander and sole occupant, an astronaut named…Gus Grissom.

To prevent such occurrences on future missions, NASA re-designed the hatch yet again, this time to make it more secure.

But ironically, that re-designed hatch would prove to be a contributing factor in one of the worst disasters in the history of space exploration.  On January 27, 1967, three astronauts were seated inside their Apollo I capsule conducting a simulated launch.  Fire broke out inside the capsule.  The re-designed multi-layered hatch was secure, all right.  So secure, it took ground technicians six minutes to open it.  But by then, the astronauts inside had succumbed to asphyxia due to carbon monoxide fumes.  Killed in the disaster were Roger Chaffee, Ed White, and another astronaut named…Gus Grissom.

 Sources:  Life in Space, a Time/Life book, and the Gus Grissom site at http://www.venus.net
 

For the week beginning September 3, 2000

Flash’s Astronomical Fact #46

A distaff is a cylindrical object around which flax is wound as part of the process for spinning it into linen. A handle attached to one end of the cylinder facilitates the winding process. In fact, the distaff-and-handle combination looks something like a rocket (with attached support standard) of the type used by the ancient Chinese.  Don't get ahead of me.  In the language of Old High German, a distaff is called a roccho.  Thus, it is because of their resemblance to a distaff-on-a-handle that we call them - rockets!

 Sources:  The Distaff site at http://www.smith.edu,Webster’s New World Dictionary, and The Guide to Self-Sufficiency by John Seymour
 

For the week beginning August 27, 2000

Flash’s Astronomical Fact #45

Question:  Where on Earth will you find the tallest volcano in the solar system?

Answer:  Nowhere.  On Earth, that is.

To find the tallest volcano in the solar system, you must journey to the planet Mars.  On the Red Planet, you will find a volcano named Olympus Mons.

Olympus Mons is located near the Martian equator, in an area called the Tharsis Plateau.

Olympus Mons is some 24 kilometers (15 miles) high.  At over 550 kilometers (340 miles) in diameter, it is over twenty times as wide as it is tall, giving it a gentle slope (a volcano of this type is called a shield volcano).  By contrast, the tallest volcano on Earth - Mauna Loa on the big island of Hawaii – rises just 9 kilometers (6 miles) from the ocean floor and is only 120 kilometers (75 miles) in diameter.  Scientists estimate that Olympus Mons may be up to 100 times as big as Mauna Loa!

Atop Olympus Mons, you will find a crater-like volcanic basin (called the caldera).  It is 80 kilometers (50 miles) across at its widest.  Within the caldera are several smaller circular depressions (called collapse craters), evidence of several volcanic events in the recent (geologically speaking) past.

Looking down from high above, Olympus Mons sports ridges that radiate from the caldera like the spokes on a bicycle wheel.  These ridges are indicative of lava flows.

Olympus Mons is bordered by a roughly circular edge (called an escarpment).  In some places, so much lava has flowed over the escarpment as to cover it up.  In other places, the escarpment takes the form of basaltic cliffs with a drop of as much as 6 kilometers (4 miles)!

Why does smaller Mars have volcanoes that are bigger than any on our larger Earth?  Mars’ low gravity plays a role, certainly.  But the biggest single factor is that the surface of Mars tends to stay fixed relative to “hot spots” of sub-surface magma. This has allowed lava to spew forth from Olympus Mons for millions of years, which in turn has allowed it to build up to tremendous proportions. On Earth, by contrast, the surface of the planet (both on land and beneath the ocean) is in constant motion atop tectonic plates.  Referring again to Mauna Loa, the Hawaiian Islands rest on the Pacific Plate, which currently is moving towards the northwest.  As the plate moves towards the northwest, it carries the Hawaiian Island chain away from the “hot spot”, which lies currently beneath Mauna Loa.  In time, the Pacific Plate will pull the big island of Hawaii off of the “hot spot”, which will result in the Mauna Loa volcano becoming increasingly inactive.  Meanwhile, a new volcano will begin to rise from the ocean floor, creating a new island for the Hawaiian Island chain.

In fact - by coincidence - the Hawaiian Island chain is, at present, about as long as Olympus Mons is wide!

 Sources:  The Olympus Mons sites at http://starchild.gsfc.nasa.gov, http://cass.jsc.nasa.gov, http://www.solarviews.com, http://antwrp.gsfc.nasa.gov, and http://www.olympusmons.com and the Hawaiian Volcanoes site at http://www.soest.hawaii.edu
 

For the week beginning August 20, 2000

Flash’s Astronomical Fact #44

America’s first Space Shuttle was to be named the Constitution.  But a letter-writing campaign by fans of the television series "Star Trek" convinced the powers that be to name it the Enterprise.  Ironically, the Trekkers’ own enthusiasm thwarted part of their objective.  For you see, the first Space Shuttle was designed solely for atmospheric test flights.  Thus, the Space Shuttle Enterprise, named for science fiction's most famous space vessel... never got into space!

 Source:  The First Space Shuttle site at http://www.geocities.com
 

For the week beginning August 13, 2000

Flash’s Astronomical Fact #43

Halley's comet passed near the Earth in April of 1066 A.D.  This event is chronicled on the famous Bayeux Tapestry.

Some say that Halley’s comet may have had a hand in the course of history.  In the Dark Ages, the appearances of comets were thought to portend disasters (such as the fall of kingdoms).  Consequently, when the Normans saw Halley’s comet, they may have taken it as a sign that some kingdom was doomed to fall.  Thus, Halley’s comet may have encouraged - if not outright precipitated - the invasion of England by William the Conqueror.  An example of a self-fulfilling prophecy?  Maybe.

 Source:  Cosmos by Carl Sagan
 

For the week beginning August 6, 2000

Flash’s Astronomical Fact #42

In the Earth’s northern temperate zone, the months of July and August tend to be hot and humid.  The ancient civilizations of the Mediterranean region (Greek, Roman, and Egyptian) had an astronomical theory to explain these meteorological conditions.

They noted that Sirius, the brightest star in Earth’s night sky, rises with the Sun around the same time that the muggy weather reaches its peak.  Believing there to be a connection between those two facts, the ancients inferred that the increase in temperature was the result of the bright star Sirius supplementing the Sun’s heat with its own.  In fact, that is how the star got its name.  Sirius derives from the Greek “seirios”, meaning “scorcher”.

But their conclusion, however intuitive, was flat out wrong.  The higher temperatures were not caused by Sirius, or any other star – or, for that matter, every star in the heavens combined.  Rather, during the summer months, the Earth's Northern Hemisphere tilts towards the Sun, thereby receiving its rays more directly.  The stars, however bright, simply lie too far away to have any effect on Earthly temperatures.  As for the humidity… well, when you couple the higher temperatures with the presence of the Mediterranean Sea, it should not be surprising that the ancient civilizations found the late summer months a tad sultry. 

The Roman name for Sirius was Canicula, meaning “Dog Star”.  Sirius/Canicula is called the “Dog Star” because it is the brightest star in the constellation Canis Major (The Great Dog).  Since the Romans believed Canicula to be the cause of the hot and humid weather, the late summer period of such was referred to as the “caniculares dies” or… “Dog Days”.

As the period of stifling weather lasted about forty days, the ancients surmised that Sirius’ effects began twenty days before the star came into conjunction with the Sun and continued for twenty days thereafter.  In modern times, Sirius rises with the Sun around July 22.  Therefore, the Dog Days begin twenty days earlier (July 3) and end twenty days later (August 11).

By the way, it was once believed that dogs became mad from the heat during the Dog Days of summer.  Actually, any madness the dogs might have been suffering most likely was due to rabies.  Rabies is a viral disease of the central nervous system; it has nothing to do with either the weather – or the stars.

 Sources:  The Dog Days sites at http://infoplease.lycos.com, http://www.reston.com, http://encarta.msn.com, http://www.astro.wisc.com, and http://www.britannica.com
 

For the week beginning July 30, 2000

Flash’s Astronomical Fact #41

At this stage of its development, the universe is expanding.  As a consequence of this expansion, every galaxy in the universe is moving away from every other galaxy in the universe.

American astronomer Edwin Hubble (1889–1953) observed (in 1929) that brighter (and presumably closer) galaxies move away from our own Milky Way Galaxy at a slower rate of speed than fainter (and presumably farther) galaxies.  Moreover, when he divided the velocity by the distance for each galaxy, it produced a figure that was the same for all galaxies.  This ratio (designated by the symbol H_o) is called the Hubble constant.

The Hubble constant is expressed in units of kilometers per second per Megaparsec or km/s/Mpc.  A Megaparsec is one million parsecs, or about 3.26 million light-years.  Using the crude instruments available to him at the time, Hubble determined that the value of the Hubble constant is 500 km/s/Mpc.  In other words, a galaxy that lies at a distance of one million parsecs recedes from the Earth at the rate of 500 kilometers per second.

In the years since Hubble’s first calculation, other scientists - using improved instrumentation – have revised the figure down to between 50 and 100 km/s/Mpc.  And there it stood for most of the latter half of the twentieth century.

Then, in 1999, NASA’s Hubble Space Telescope Key Project team concluded an exhaustive eight-year study to establish the correct value of the Hubble constant.  They determined that the Hubble constant is 70 km/s/Mpc (with an accuracy of + 10%).  And yes, you read right.  The orbiting Hubble Space Telescope, named for Edwin Hubble, aided in the effort to determine the correct value of the Hubble constant.  Appropriate.

The Hubble constant has implications not only for the size of the universe, but also its age.  The faster the rate at which the universe expands, the less time required for the universe to attain a given size.  Thus, a high value for the Hubble constant implies a comparatively younger universe; a low value, an older universe.

The Key Project team’s downward revised figure cleared up some troubling paradoxes.  Using the previous high-end figure for the Hubble constant (100 km/s/Mpc), astronomers calculated that the age of the universe was less than that of some of the oldest stars in it - which clearly would be impossible.  The 70 km/s/Mpc figure results in an age for the universe that conforms nicely with the ages of the universe’s oldest stars.

 Sources:  The Hubble Constant site at http://www.csep1.phy.ornl.gov, and Time Almanac 2000
 

For the week beginning July 23, 2000

Flash’s Astronomical Fact #40

A partial solar eclipse will be visible from the northwestern continental United States, western Canada, and Alaska on July 30, 2000.

When we were old enough to understand spoken words, we were instructed by our parents NEVER to look directly at a solar eclipse.  And that is, certainly, sound advice.

But, aside from some vague warning about the possibility of damage to one’s eyes, we were never told exactly why is it dangerous to look directly at a solar eclipse.  In this edition of Flash’s Astronomical Facts, I will tell you the why of it; which I hope will impress upon you – and your children – why you must be careful when viewing a solar eclipse.

Here is the skinny:  There is nothing mystical, demonic, or even intrinsically dangerous about the eclipse itself.  It is simply that the eclipse, being a fascinating phenomenon, might entice one to look at it - which means also looking at the Sun.  And it is dangerous to look at the Sun at any time, eclipse or not.

The Sun emits energy in the form of electromagnetic radiation (electromagnetic radiation is the only way that energy can be transmitted through a vacuum, such as that of outer space).  The most well known type of electromagnetic radiation is visible light. But the Sun emits other types of electromagnetic radiation as well. One of these is an invisible type called infrared radiation.  Infrared rays are commonly known as heat rays because they induce heat in any object they touch.  Another invisible type is ultraviolet radiation.  Ultraviolet rays propagate through space at a higher frequency than visible light and are, therefore, more energetic. 

The innermost lining on the backside of the eyeball is called the retina.  The surface of the retina is studded with over 125 million photoreceptor cells, popularly known (because of their shapes) as rods and cones.  These light-sensitive rods and cones are extensions of the optic nerve.  When light energy strikes the rods and cones, they become excited.  The exact degree of excitation depends on the intensity and frequency of the light falling upon them.  In this way, the rods and cones transmit to the brain, via the optic nerve, details of the light coming through the eyes.  The brain then processes this information into visual images.

When one looks at the Sun, one is exposing the retinas of one’s eyes to the Sun’s rays.  Infrared and ultraviolet radiation, each in different ways, can damage severely the rods and cones.

But here is the insidious part.  The retina has no pain receptors.  Thus, someone determined to observe a solar eclipse without proper eye protection will not feel any pain and, therefore, will not realize that damage is being done to his eyes.  In fact, several hours may pass before the injury manifests itself in a way that can be felt, specifically as a burning sensation in the eyes. But by then, it will be far too late.  The damage already will have been done.  The eclipse watcher will suffer temporary – or permanent – blindness.

See this week’s edition of Flash’s Helpful Hints for information on how to observe safely a solar eclipse.

 Sources:  The Solar Eclipse Safety sites at http://www.preventbe.org, http://www/roe.ac.uk, and http://www.eclipse.org.uk, and the Rods and Cones site at http://www.gansmart.com
 

For the week beginning July 16, 2000

Flash’s Astronomical Fact #39

What name will be given to a newly discovered moon?  Or to surface features on that moon?  Where lie the boundary lines between constellations?  For that matter, what constitutes a constellation?

Who decides all this stuff?

Obviously, there would be no end to the confusion if one astronomer gave a newly discovered heavenly body one name, and a different astronomer gave it a different name. 

Just as weights and measures are standardized to facilitate trade, the names of heavenly bodies must be standardized to facilitate astronomical research.  Civil governments fix the standard of weights and measures.  But the task of naming objects in the heavens falls to a professional body:  The International Astronomical Union (IAU).

Founded in 1919 and based in Paris, France, the mission of the IAU is a simple, but important one:  To promote the scientific progress of astronomy.

The IAU is not chartered by any government or international organization.  It is a truly independent body of professional scientists, and beholden to no nation or group of nations.

It is not easy to join the IAU.  To become a member, one must have a doctorate in the field of astronomy, and be active in astronomical research or teaching.  In spite of these high standards, some 8,300 of the world’s top astronomers, representing 83 countries, are members of the IAU.

But rest assured, the IAU is not an association of ivory tower snobs.  As part of its mission to promote astronomical research, the IAU maintains contacts with other scientific organizations, including amateur astronomy groups.

To facilitate its work, the IAU is organized into eleven worldwide Divisions.  The IAU also directs forty Commissions that tackle a variety of specialized tasks.

The IAU is proof to you young people that Bill Clinton’s example is not to be followed.   Honesty, integrity, and forthrightness really are virtues worth pursuing; and those virtues have served the IAU well.  By “checking their egos at the door”, as it were, the IAU’s credentials are unimpeachable.  Scientists and scientific organizations all over the world hold the IAU in high regard and defer to its decisions regarding the naming of heavenly bodies.  Even nations not represented among the IAU’s membership adhere to its findings. They know full well that the IAU subjects every astronomical matter to the best possible scientific review.  And certainly, no one can claim credibly that he could have done a better job.  Remember, the IAU has no legal authority to impose its decisions on anyone.  Its only authority is moral authority.  By acting respectably, the IAU is respected.

Someday, you may have dealings with the IAU.  I’m serious.  For you see, most comets are discovered not by professional astronomers, but by amateurs.  If you believe that you have spotted a new comet with your backyard telescope, report it to the IAU’s Central Bureau for Astronomical Telegrams (CBAT).  And be quick about it.  The first person to contact the CBAT gets the honor of having the comet named after him.  Remember, when it comes to naming objects in the heavens, the IAU has the final say.

 Source:  The International Astronomical Union site at http://www.iau.org
 

For the week beginning July 9, 2000

Flash’s Astronomical Fact #38

The orbit of the planet Pluto is so eccentric that it actually crosses the orbit of Neptune.  For twenty years out of Pluto’s two hundred and forty-eight year orbit, Neptune - not Pluto - is the outermost planet.

So, the question naturally arises, “Is there any chance that Neptune and Pluto will collide?”

And the answer is, no.  For several reasons.

First, the orbits of Neptune and Pluto do not cross in the usual meaning of word.  Looking downward from a point above the plane of the solar system, the orbits indeed seem to intersect, with Pluto’s highly elliptical orbit crossing the nearly circular orbit of Neptune.

But a three-dimensional perspective tells a different story.  Pluto’s orbit is inclined a whopping 17.00 degrees relative to the plane of the Earth’s orbit (called the ecliptic), whereas Neptune’s orbit is inclined only 1.77 degrees.  Thus, the two orbits overlap without intersecting.  If this seems a little confusing, think of it this way:  The orbital paths of Neptune and Pluto are not like intersecting city streets; they are like freeway exchanges, with their overpasses and underpasses.

As if the preceding were not enough, the orbits of Neptune and Pluto are set in a three-to-two ratio called orbital resonance.  In other words, Neptune completes three orbits every time Pluto completes two.  Moreover, the planets are spaced about as well as they can be spaced to avoid collision.  Thus, when Pluto is at the crossover points, Neptune is nowhere near.  In fact, though it is hard to believe, Pluto actually gets closer to Uranus (11 Astronomical Units, or about 1.02 billion miles) than it ever does to Neptune (17 Astronomical Units, or about 1.58 billion miles).

These factors have kept Neptune and Pluto from colliding for billions of years.  And - barring some extraordinary cosmic event - they will continue to keep the worlds apart for billions of years to come.

 Sources:  Voyage Through the Universe/Atlas, a Time/Life Book series, and the Pluto’s Orbit sites at http://www.image.gsfc.nasa.gov, http://www.seds.lpl.arizona.edu, and http://www.earthsky.worldofscience.com
 

For the week beginning July 2, 2000

Flash’s Astronomical Fact #37

In honor of the upcoming Fourth of July holiday, this edition of Flash’s Astronomical Facts will present a special fact about a special group of stars:  The stars on the American flag.

One question about the American flag that is frequently asked is:  How did the flag of the United States come to have five-pointed stars (called pentagrams) instead of, say, six-pointed stars?

Flags with six-pointed stars were not unknown. In fact, the Bennington battle flag of the American Revolution era bore six-pointed stars.  Moreover, George Washington himself is said to have favored six-pointed stars.

So, how did we end up with five-pointed stars?

Well, as with many stories of the American Revolution, some specific points are shrouded in mystery and have generated much debate among historians.  With that caveat, the following account is the consensus opinion of how the American flag came to have five-pointed stars:

A secret committee from the Continental Congress, consisting of General George Washington, Robert Morris, and Colonel George Ross contacted Betsy Ross to commission her to sew the first American flag.  That Betsy Ross was sought out for this assignment was not happenstance.  As you may have surmised, she was indeed related to George Ross (he was the uncle of Betsy’s late husband, John Ross).  Believe it or not, Betsy Ross even knew George Washington by previous social contact (they attended the same church).  The only member of the committee who was a stranger to her was Mr. Morris, a wealthy landowner.

George Washington presented to Betsy Ross a pencil sketch of the proposed design for the flag, which included stars of the six-pointed variety.  Betsy Ross suggested five-pointed stars, on the grounds that they would be easier to cut from cloth.

The committee initially rejected her proposal as ludicrous.  How could a star with an uneven number of points be produced more easily than a star with an even number of points?  The very idea was preposterous.

But Betsy Ross, an expert seamstress, knew her craft.  She picked up a piece of paper, folded it in a certain way, and – with a single snip of her scissors – cut a perfect five-pointed star right before the committee’s very eyes.

This seemingly magical feat apparently impressed the committee, for they acceded immediately to her suggestion that the flag be spangled with five-pointed stars.  Having proven that she knew what she was doing, the committee placed the project in her capable hands – and the rest is history.

Whether or not this account is the complete truth, it is a fact that you can cut a perfect pentagram star from folded paper, just as did Betsy Ross.  Access the website listed below for complete, illustrated, step-by-step instructions.

Happy Fourth of July, everyone.

 Source:  The Betsy Ross site at http://www.ushistory.org

This site is an excellent source of information about Betsy Ross and the American Flag.
 

For the week beginning June 25, 2000

Flash’s Astronomical Fact #36

You may have heard or read somewhere that the presence of liquid water is considered to be one of the most important factors in determining whether or not a planet is capable of developing and supporting life.

But just what is it about water that makes it so essential for life processes here on the Earth – and possibly other worlds?

Water has a number of qualities and properties that facilitate the formation and continuance of life.  Among other things:

Water has a high specific heat.  That is to say, it is capable of absorbing large quantities of thermal energy while increasing in temperature only slightly.  In other words, liquid water is one of the best heat moderators there is.  And when the temperature of the water remains steady over the course of billions of years, life gets a chance to evolve.

Water is a near-universal solvent. Given enough time, water can dissolve practically anything.  This enables it to break rocks and biological material down to the molecular level, thus putting minerals and nutrients in suspension, providing sustenance for aquatic life forms.

Water not only dissolves substances, it transports them as well.  And I do not mean simply that it will carry nutrients to the life forms.  It also will carry those nutrients throughout the body of the life form.

Water has one of the best dipole moments of all common substances.  A thorough explanation of dipole moments is beyond the scope of this discussion.  Suffice it to say, substances with good dipole moments facilitate biological processes.

Water is composed of two atoms of hydrogen and one atom of oxygen.  And hydrogen and oxygen are two of the most important elements for life.  If fact, through photosynthesis, water is responsible for the presence of most of the molecular oxygen in the atmosphere.

Water also has one more unique property.  Unlike most substances, water expands as it freezes.  This makes the solid form less dense than the liquid form.  This is why ice floats on the water’s surface.  If ice sank, the entire ocean eventually would freeze solid.  As it is, the entire surface of a lake can freeze into ice while fish continue to thrive in the liquid water beneath.  This is good not only for ice fishermen, but for life in general.

Given all that it can do, it is a virtual certainty that ET needs water every bit as much as we Earth humans.

 Sources:  The Life on Other Worlds sites at http://www.livingcosmos.com, http://www.msnbc.com/news/SPACELIFE, and http://www.wcresa.k12.mi.us 
 

For the week beginning June 18, 2000

Flash’s Astronomical Fact #35

Everyone wants Space Shuttle missions to go perfectly, from start to finish, without incident.  However, while we all hope for the best, we must prepare for the worst.

NASA has drawn up a number of contingency plans to enable the Shuttle and her crew to return safely to the Earth in the event that an emergency situation (most likely, a failure of the three Space Shuttle Main Engines (SSMEs) to boost the craft to the proper altitude) forces the mission to be aborted.  Which plan they would use would depend on a number of factors, including the craft’s position, altitude, and time of flight at the moment the emergency is declared, as well as the exact nature of the emergency.

The first scenario is the practically self-explanatory Return to Launch Site (RTLS).  In this scenario, the Shuttle would continue on powered flight until such time as she could jettison safely both her twin Solid Rocket Boosters (SRBs) and her large External Tank (ET).  The craft would then glide unpowered back to the launch site and make a landing in the usual manner.  Landing sites in the continental United States are Kennedy Space Center (Florida), Edwards Air Force Base (California), and White Sands (New Mexico).  RTLS aborts are feasible between liftoff and T-plus four minutes and twenty seconds.

If the Shuttle is more than four minutes and twenty seconds into her flight, the next scenario is a Transatlantic Abort Landing (TAL).  All spacecraft are launched eastward so as to go with, rather than against, the rotation of the Earth.  Were an emergency to be declared while the Shuttle is over the Atlantic Ocean, the craft would continue for a time on powered flight, like a projectile.  At a selected point, the Solid Rocket Boosters and External Tank would be jettisoned, after which the craft would glide unpowered to an alternate site and make a landing in the usual manner.  Alternate landing sites are available in the cities of Moron (Spain), Ben Guerur (Morocco), and Dakar (Senegal).  Which of the three would be chosen would depend on the Shuttle’s exact position and altitude at the time of the abort, as well as local weather conditions at the alternate landing sites.

If the Shuttle is past the point where a TAL is feasible, the next scenario is an Abort Once Around (AOA).  In other words, the craft would make one orbit of the Earth and then come in for a landing in the usual manner.

Another scenario is the seemingly oxymoronic Abort to Orbit (ATO).  This scenario comes into play in situations where the Shuttle otherwise is operating properly, but the propulsion systems have failed – just barely - to boost the craft to its planned orbit.  Under such circumstances, NASA may decide that the best course of action is to have the Shuttle remain in a lower - albeit still safe and sustainable - orbit.  In fact, after the launch of mission STS-51F, the Space Shuttle Challenger underwent an ATO, yet still managed - despite its lower orbit - to complete successfully her mission.

The final scenario is the most frightening of them all.  It is called a Contingency Abort.  If, at any time, it appears that the craft will not be able - for whatever reason - to land safely, the crew may have no choice but to eject from the Shuttle.  This they would accomplish by means of the Inflight Crew Escape System (ICES).  First though, the craft would have to be set on a glide path that would 1) enable the crew to eject safely; and 2) make the abandoned Shuttle ditch in the ocean so that it comes down well clear of populated areas.

But what if the Shuttle cannot be put on a glide path that would enable the crew to eject safely?  In that case, the crew may be forced to ride the Shuttle down and ditch in the ocean along with the craft.

 Source:  The Space Shuttle Performance site at http://www.kipertek.com
 

For the week beginning June 11, 2000

Flash’s Astronomical Fact #34

Modern astronomers, aided by sophisticated instruments, can detect the motions of the stars with ease.

But the ancients had only their unaided eyes with which to view the heavens.  They could not detect the motions of the stars.  The stars were moving, yes.  But, because the stars lie so far away, humans could not discern their changes in position from day to day; or, for that matter, even over the course of a human lifetime.  To the ancients, the stars appeared to be affixed permanently to an inverted bowl above their heads.  Hence, they referred to them as fixed stars.

However, the ancients did notice that five of the points of light in the night sky did move noticeably relative to the so-called “fixed stars”.  These objects’ motions were detectable because they lie relatively close to the Earth.  The ancient Greeks referred to these objects as planetes, meaning “wanderers”. This is the source of the word planet.

 Source:  Time Almanac 2000
 

For the week beginning June 4, 2000

Flash’s Astronomical Fact #33

Two of the most unusual star names are Sualocin and Rotanev.  They are, respectively, the first and second brightest stars in the constellation Delphinus (The Dolphin).

From whence came these unusual names?  Here is the story:  In the year 1814, the stars of Delphinus were about to be listed in a catalog being prepared by Guisepe Piazzi, then director of the Palermo Observatory.  His assistant, Niccolo Cacciatore, was a vainglorious man who wanted to name the two brightest stars of Delphinus after himself, doubtless as a means of attaining a bit of immortality.  However, he knew that director Piazzi would never approve, as it was considered conceited for an astronomer to name stars after himself.  That sort of thing was simply not done. 

But the crafty assistant devised a way to skirt that unwritten rule.  He suggested to Piazzi that the stars be named Saulocin and Rotanev.  The director, probably under the pressure of his work, did not bother to ask from whence the names came.  From whence they came was from the devious mind of Niccolo Cacciatore.  You see, if you take the names Sualocin and Rotanev and reverse the order of the letters of them both, they spell Nicolaus Venator – the Latin equivalent of Niccolo Cacciatore!

By the time anybody got wise to the gag, the star names had become too established to change - and therefore continue to be used to this day.  Thus, Niccolo Cacciatore – a.k.a. Nicolaus Venator – is the only man in history ever to get away with naming stars after himself!

Bill Clinton would be proud.

 Source:  The Delphinus sites at http://homex.s1.net.sq, http://www.astroinfo.ch, and http://www.mtsn.tn.it
 

For the week beginning May 28, 2000

Flash’s Astronomical Fact #32

In Flash’s Skywatcher’s Almanac, you may have noticed that every other week I note that the Moon either is at ascending node or descending node.  In this edition of Flash’s Astronomical Facts, I will define those terms.

First, some background.

As you know, planet Earth orbits the Sun. The plane defined by the Earth’s orbit is called the ecliptic.

At the same time that the Earth is orbiting the Sun, the Moon is orbiting the Earth.  However, the Moon’s orbit does not coincide with the ecliptic.  Instead, the plane of the Moon’s orbit around the Earth is inclined (that is, tilted) about five degrees relative to the ecliptic.  Therefore, at certain times in the Moon’s orbit, the satellite will be above the ecliptic; at other times, it will be below the ecliptic (by convention, the Earth’s North Pole is presumed to be above the ecliptic, and the South Pole is presumed to be below the ecliptic).  Where the plane of the Moon’s orbit and the ecliptic intersect, there is a line segment called the line of nodes.

When the Moon breaks the plane of the ecliptic heading from south to north, the Moon at that time is said to be at the ascending node; conversely, when the Moon breaks the plane of the ecliptic heading from north to south, the Moon at that time is said to be at the descending node.

The inclination of the Moon’s orbit relative to the ecliptic explains why eclipses are relatively rare.  If the plane of the Moon’s orbit coincided with the ecliptic, a solar eclipse would occur at every New Moon, and a lunar eclipse would occur at every Full Moon.  Instead, an eclipse can occur only on those occasions when the line of nodes exactly or closely coincides with a line between the Earth and the Sun.  And that happens only about every six months.

 Sources:  The Old Farmer’s Almanac and Voyage Through the Universe/Moons and Rings, a Time/Life Book Series
 

For the week beginning May 21, 2000

Flash’s Astronomical Fact #31

The planet Uranus has rings, but that fact was not discovered by either of the Voyager probes.  Instead, the rings were found to exist as the consequence of a ground-based photometric experiment.  In 1977, Uranus was on track to occult (cover) a red giant star.  Instruments on Earth were set up to record two sets of lights; blue light from the planet and red light from the star.  The red light dropped almost completely off the chart when the planet passed in front of the star.  The astronomers had expected that.  But something else happened that they did not expect.  The intensity of the red light dipped slightly at nine distinct points on either side of the planet.

Scientists analyzing the chart determined that the slight dips in light intensity took place beyond the edge of the planet.  Moreover, the light intensity dips occurred in an inhomogeneous pattern. In other words, the light intensity dips at some points were slight, at other points comparatively greater.  The spacing between the dips varied as well.  But most significantly of all, the pattern of light intensity dips on one side of the planet mirrored precisely the pattern on the other side of the planet.  These facts led astronomers to conclude that the light intensity dips were caused by the presence of light-blocking rings around the planet.

In 1986, Voyager II photographed the nine rings found to exist by the Earth-based experiment.  In addition, the probe found two more rings, bringing to eleven the number of known Uranian rings.

 Source:  Voyage Through the Universe/The Far Planets, a Time/Life Book Series and Time Almanac 2000
 

For the week beginning May 14, 2000

Flash’s Astronomical Fact #30

Most stars shine steadily, their brightness never changing over the course of a human lifetime.  But there exist a certain class of stars whose brightness changes considerably over a very short span of time, ranging from as much as many years to as little as several days.  The fourth brightest star in the constellation Cepheus (The King) was the first such star ever observed.  Hence, stars of this class are called Cepheid variables. 

Not only does the brightness of a Cepheid variable change over a nominal span of time, scientists have discovered that there is a correlation between the pulsation rate and the variation in intrinsic brightness.  In other words, an astronomer, looking for the first time at a Cepheid variable, can tell – just from the pulsation rate – what the variation in intrinsic brightness is.  And it is the variation in intrinsic brightness that gives astronomers clues as to how far away that star (and hence, any object in its vicinity) lies.

Recently, astronomers used twenty Cepheid variables to measure the distance to the galaxy (designated as M100) that contains them.  They were able to determine that M100 lies 56 million light-years away.  So strong is the correlation between the pulsation rate and the variation in intrinsic brightness of Cepheid variables, scientists are confident that their estimate is correct to within plus or minus six million light years!  Considering the distances involved, this can be termed a very good estimate indeed.

 Source:  The Cepheid Variables site at http://oposite.stsci.edu
 

For the week beginning May 7, 2000

Flash’s Astronomical Fact #29

The previous two editions of Flash’s Astronomical Facts covered the topic of lunar phases.  We began by describing the New Moon, First Quarter, Full Moon, and Third (or Last) Quarter phases the Moon exhibits at the quarter points of its orbit.  Next, we discussed the Crescent phase that the Moon exhibits in the days just before or just after New Moon, and the Gibbous phase that the Moon exhibits in the days just before or just after Full Moon.

We will conclude our discussion of lunar phases by relating the sequence of phases.

After New Moon, the lighted portion of the Moon’s surface grows larger with each passing day, culminating in Full Moon, when the entire surface is bathed in sunlight.  This period in the Moon’s orbit is called the waxing period.  Waxing comes from the Old English weaxan, meaning “to grow more”.

Conversely, after Full Moon, the lighted portion of the Moon’s surface grows smaller with each passing day, culminating in New Moon, when the entire surface is again shrouded in darkness.  This period in the Moon’s orbit is called the waning period.  Waning comes from the Old English wanian, meaning “to grow less”.

Here is the sequence of phases, using New Moon as our starting point:  New Moon – Waxing Crescent – First Quarter – Waxing Gibbous – Full Moon – Waning Gibbous – Third Quarter – Waning Crescent – New Moon.

Naturally, the best way to understand this sequence is to go outside every evening for a month (weather permitting) and note how the Moon’s appearance changes day by day.  After all, the Moon is the sky’s biggest visual aid.

 Sources:  Voyage Through the Universe/Moons and Rings, a Time/Life Book Series, the Lunar Phases site at http://www.calvin.edu and the Orbits and Phases of the Moon site at http://csep10.phys.utk.edu
 

For the week beginning April 30, 2000

Flash’s Astronomical Fact #28

In the previous edition of Flash’s Astronomical Facts, we discussed lunar phases:  The changes in the Moon’s appearance resulting from sunlight falling on different portions of the Moon at different points in its orbit.

In particular, we discussed the phases exhibited at the four quarter points in the Moon’s orbit:  New Moon, when the entire surface appears shrouded in darkness; First Quarter, when the right half of the satellite is illuminated; Full Moon, when sunlight reflects off of the entire portion that faces the Earth; and Third (or Last) Quarter, when the left half of the satellite is illuminated.

In between these quarter points, the Moon takes on other appearances that have names of their own.

In the days just before or just after New Moon, the lighted portion is concave in shape.  This is called a Crescent Moon.  Crescent comes from the Latin crescere, meaning “to grow” or “to come forth” (which is exactly what the thin, lighted sliver does following New Moon).

Conversely, in the days just before or just after Full Moon, the lighted portion is convex in shape.  This is called a Gibbous Moon.  Gibbous comes from the Latin gibba, meaning “hump”.

The Crescent and Gibbous phases are significant in another way.  Because such shapes are possible only when light falls on a spherical surface, the Crescent and Gibbous phases alone are irrefutable astronomical proof that the Moon is not a flat disc in the sky, but in fact a round ball.

In the next edition of Flash’s Astronomical Facts, we will conclude our discussion of lunar phases.

 Sources:  Voyage Through the Universe/Moons and Rings, a Time/Life Book Series, the Lunar Phases site at http://www.calvin.edu and the Orbits and Phases of the Moon site at http://csep10.phys.utk.edu
 

For the week beginning April 23, 2000

Flash’s Astronomical Fact #27

Over the course of the Moon’s 29½-day orbit around the Earth, the appearance of the Moon changes.  Certain portions of the Moon reflect sunlight and seem to be illuminated, while other portions are resigned to darkness.  These changes in appearance are called phases.  Special names are given to phases at significant points in the Moon’s orbit.

We begin with the Moon positioned between the Sun and the Earth.  Sunlight falls only on that portion of the Moon that faces away from the Earth, thus leaving the near side – that is, the side facing us - in total darkness.  This phase begins the lunar cycle, so it is called New Moon.

A little over seven days later, the Moon will have moved in its orbit to where the Earth, Moon, and Sun form a right triangle.  Sunlight now falls on the Moon in such a way that the right half appears illuminated.  Because this occurs when the Moon has moved one-quarter of the way in its orbit after New Moon, this phase is called First Quarter.

A little under fifteen days after New Moon, the Moon again lines up with the Earth and Sun, but this time it is the Earth that lies between the Sun and the Moon.  Sunlight falls completely on that portion of the Moon that faces the Earth.  Because the Moon appears fully lighted, this phase is called Full Moon.

A little over seven days after Full Moon, the Moon will have moved in its orbit to where once again the Earth, Moon, and Sun form a right triangle.  Only this time, sunlight falls on the Moon in such a way that the left half appears illuminated.  Because this occurs when the Moon has moved three-quarters of the way in its orbit after New Moon, this phase is called Third Quarter.  However, because the Moon is only one-quarter of the way from once again becoming a New Moon, this phase sometimes is referred to as Last Quarter.  Astronomers use both terms.  They are equal and interchangeable.

A little under fifteen days after Full Moon, the Moon once again will have returned to a point in between the Sun and the Earth, once again to become a New Moon - and the cycle of lunar phases begins anew.

More on lunar phases in the next edition of Flash’s Astronomical Facts.

 Sources:  Voyage Through the Universe/Moons and Rings, a Time/Life Book Series, the Lunar Phases site at http://www.calvin.edu and the Orbits and Phases of the Moon site at http://csep10.phys.utk.edu
 

For the week beginning April 16, 2000

Flash’s Astronomical Fact #26

With Easter Sunday coming up, now is a good time to review how the date of Easter Sunday is determined.

If you ask the average person on the street how the date of Easter Sunday is determined, he or she probably will say, “Easter Sunday is the first Sunday following the first Full Moon occurring on or after the first day of spring (i.e., the vernal equinox)”.  But, while this rule is commonly spoken and heard, it is not correct. The actual method is a bit more  complicated.  Just bear with me.  We will go through it step-by-step.

The Church recognized that there are several problems with allowing the date of Easter Sunday to be determined according to the exact timing of astronomical events.  For one thing, the northern hemisphere vernal equinox (defined as the moment when the Sun crosses the celestial equator from south to north) does not occur on the same day every year (it can vary from 8:00 a.m. (CST) on March 19 to 1:00 p.m. (CST) on March 21).  Moreover, the exact date and time of the vernal equinox in any given year varies according to longitude.  For example, the vernal equinox might occur late in the evening of the 20th of March in one time zone, while in another time zone it might occur early in the morning of the 21st of March.

Throw a Full Moon into the mix, and things can really get out of whack.  Expanding on the above example, what if the Full Moon occurs on the 20th day of March?  It would mean that Christians living in the former time zone would celebrate Easter the Sunday following, while Christians in the latter time zone would have to wait until the Sunday following the next Full Moon.

To counter those drawbacks, the Council of Nicaea established (in 325 A.D.) the rules and conventions for determining the exact date of Easter Sunday.  First, for the sole purpose of determining the date of Easter Sunday, the date of the vernal equinox was fixed at March 21.  In other words, the 21st day of March is presumed to be the date of the vernal equinox, regardless of whether or not that is true astronomically.  This presumptive date of the vernal equinox is called ecclesiastical equinox.

The first Full Moon to occur on or after the ecclesiastical equinox is called – surprise, surprise - ecclesiastical Full Moon.

These conventions make the date of Easter Sunday the same all over the planet, regardless of time zone.  Moreover, the date of Easter Sunday can be determined far into the future.  In fact, tables have been established that give the date of Easter Sunday for the next several hundred years.  Within the last few decades, mathematical algorithms have been developed that enable one to calculate the date of Easter Sunday for any given year.

Incidentally, Easter Sunday 2000 will occur on the 23rd day of April, and that is almost as late as the holiday can occur.  Easter Sunday can occur as early as the 22nd day of March or as late as the 25th day of April.

Easter Sunday is one of the holiest days on the Christian calendar, as the holiday celebrates (with a feast) the resurrection of Jesus.  Because the date of Easter Sunday can vary, the celebration is called a movable feast.

 Sources:  Time Almanac 2000, the Date of Easter site at http://aa.usno.navy.mil and the Vernal Equinox site at http://www.stcloud.msus.edu 
 

For the week beginning April 9, 2000

Flash’s Astronomical Fact #25

Deep-space probes such as Voyager I not only have sent back to Earth incredible amounts of telemetered data, but also spectacular photographs.  These photographs are better than any that could be obtained from an Earth-based telescope, and not just because they are taken from close up.  A space probe’s camera does not have to shoot through the Earth’s distorting atmosphere.  The resulting color prints are awe-inspiringly beautiful.

One problem does remain, however.  In true colors, features that lie next to each other may not be distinguishable to the eye.  For example, if a light-red feature lies next to a medium-red feature that in turn lies next to another light-red feature, it may be difficult for the eye to see where one feature ends and another begins.

Scientists solve this problem by enlisting the aid of the computer.  The space probe transmits the photographs to Earth by converting the visual image into digitized data.  The computer takes the digitized information and assigns to each feature a color that will contrast well with the colors of adjoining features. Thus, instead of the features being colored light red, medium red, light red, they might be colored blue, orange, purple.  This technique is called reproduction in false colors.

False colors aid astronomers in scientific analysis.  In true colors, Saturn appears to have just a few broad rings.  In false colors, it is easy to see that Saturn’s rings are actually tens of thousands of individual ringlets.

 Source:  Voyage Through the Universe/The Far Planets, a Time-Life Book Series
 

For the week beginning April 2, 2000

Flash’s Astronomical Fact #24

In the previous edition of Flash’s Astronomical Facts, we traced the origins of the word “meteor” and discovered that meteor can refer either to the body itself as it plummets through our atmosphere or to the fiery streak it leaves in its wake.

In this edition, we will tackle that most confusing question...

What is the difference between a meteoroid, a meteor, and a meteorite?

A meteoroid is one of any of the various kinds of small rocky or metallic bodies that travel through outer space.  When a meteoroid plunges into our atmosphere (as evidenced by the fiery streak due to air friction that it leaves behind), it is called a meteor.  If any portion of the meteoroid survives the passage through our atmosphere to land upon the Earth as a solid mass of stone or metal, that portion is called a meteorite.

In brief:  When it is drifting in space, it is a meteoroid; while it is moving through our atmosphere, it is a meteor; upon hitting the Earth, it is a meteorite.

Got that?

You’re welcome.

 Source:  Webster’s New World Dictionary
 

For the week beginning March 26, 2000

Flash’s Astronomical Fact #23

The word “meteor” originally did not refer to the falling body itself, but rather just to the fiery streak it leaves behind.  The ancients did not know the true cause of meteoric streaks. They believed that a meteor (as originally defined) was the consequence of one of the stars dropping out of the heavens and falling towards the Earth (hence the term falling star).  Literally translated from the Greek, the word “meteor” means “something high up in the air” (by the way, this is the reason that the branch of science involved with the weather is called meteorology – the study of that which is high up in the air).

Nowadays, we know that meteoric streaks are caused by meteoroids - small bodies of rock or metal that travel through outer space.  When one of these solid bodies plunges through the Earth’s atmosphere, air friction heats up the meteoroid, leaving a bright trail of ionized gas in its wake.

As a result of this new understanding, the definition of the word “meteor” has been expanded.  “Meteor” can refer either to the fiery trail or to the meteoroid while it is moving through the Earth’s atmosphere.

In the next edition of Flash’s Astronomical Facts, we will discuss further the subject of meteors and clear up a few definitions.

 Source:  Webster’s New World Dictionary
 

For the week beginning March 19, 2000

Flash’s Astronomical Fact #22

One of mankind’s greatest dreams is to build a space vehicle capable of reaching another star system within the space of a human lifespan.

But trying to accelerate a starship to the velocities necessary to accomplish such a voyage will require enormous amounts of energy.  And generating that energy will require in turn enormous amounts of fuel.  The problem:  Any fuel carried on board increases the starship’s total mass.  And every kilogram of additional mass is just one more kilogram’s worth of inertia that will have to be overcome.  And remember, we are not talking about just the additional mass of the fuel itself, but also the additional mass of the containment vessel(s) and the necessary operating systems (conduits, pumps, etc.).  The fuel mass problem alone would seem to make interstellar space travel impractical, if not outright impossible.

In the 1960s, physicist Robert Bussard developed an innovative solution to this problem.  His idea is based on the fact that outer space is not a perfect vacuum.  Even in the deepest of deep space, each cubic centimeter of seeming nothingness still will contain a few hydrogen atoms or hydrogen ions.

Bussard’s design places a gigantic cone at the front of the starship, with the cone’s base facing the direction of travel.  The vessel’s main reactor will produce power by the fusion of hydrogen into helium.  A portion of that power will be directed into the starship’s forward cone to produce a cone-shaped magnetic field ahead of the ship.  As the vessel moves through space, the magnetic field – which will be 3,200 kilometers (2,000 miles) across at its widest - will gather interstellar hydrogen and funnel it to the fusion reactor to produce more power.  Thus, virtually no fuel will need to be carried. The starship will mine the very space before it, scooping up hydrogen as it goes, replenishing continuously its fuel supply.  Incidentally, though Bussard called his creation an interstellar ramjet, starships incorporating his design concept have come to be called Bussard ramscoops.

And just how fast could a Bussard ramscoop traverse the heavens?  Based on the amount of hydrogen estimated to exist in interstellar space, scientists calculate that a Bussard ramscoop should be capable of attaining speeds equal to fifty percent of the velocity of light!

 Source:  Voyage Through the Universe/Starbound, a Time-Life book series
 

For the week beginning March 12, 2000

Flash’s Astronomical Fact #21

How massive is the Sun? Consider this: The Sun generates energy at its core by fusing hydrogen into helium. Hydrogen is consumed at the rate of 700 million tons per second! Consider this also: This process has been going on for nearly five billion years - and can continue for at least another five billion years. You do the math. 

 Source: The Sun site at http://www.deepspace.ucsb.edu 
 

For the week beginning March 5, 2000

Flash’s Astronomical Fact #20

You probably know that Halley's Comet is named for English astronomer Edmund Halley (1656-1743), the man who predicted that the Great Comet of 1682 (as it was known then) would return to the vicinity of the Earth in 1758. When Halley's prediction came to pass, it established that the Great Comets of years past were not different comets, but simply the same comet making regular returns. As a result, this once-every-76-years visitor was re-named Halley's Comet in his posthumous honor. As I said, you probably know that.

What you may not know is that Edmund Halley was a brilliant mathematician and multidisciplinary researcher. In addition to calculating the orbits of comets, he catalogued the stars in the southern sky, studied the details of the Moon's orbit, and investigated the proper motions of the stars.

Halley applied his mathematical acumen to many fields of science. He made inquiries into such phenomena as trade winds, tides, the Earth's magnetic field, and the relationship between barometric pressure and the weather. As a result, he is generally regarded as being the father of the science of geophysics.

Halley was equally adept in matters involving pure mathematics. He applied mortality tables to the problem of calculating annuities.

But Halley's greatest single contribution to science was in providing professional encouragement and financial backing to his friend and colleague Isaac Newton for the publication of a book called Principia Mathematica. Principia, inarguably the greatest scientific volume ever published, is the book in which Newton first describes his Three Laws of Motion.

In the annals of science, Edmund Halley is truly one of the unsung heroes.

 Sources: Cosmos by Carl Sagan and The Edmund Halley sites at http://scrtec.rtec.org, and http://hyperhistory.com
 

For the week beginning February 27, 2000

Flash’s Astronomical Fact #19

The Earth's Moon could never collapse and become a black hole because it lacks sufficient mass. However, to give you an idea of the mass-to-size ratio, let us assume - for the sake of discussion - that it were possible for any piece of matter to collapse into a black hole. So saying, if the Earth's Moon were to collapse into a black hole, it would be no larger than the period at the end of this sentence.

 Source: The Science in Science Fiction by Peter Nicholls
 

For the week beginning February 20, 2000

Flash’s Astronomical Fact #18

Since ancient times, many cultures have attributed deranged behavior in humans to the Moon - particularly the Full Moon. The scientific name for the Earth's Moon is Luna. This is how we came to refer to a mentally unbalanced individual as a - lunatic!

 Source: Webster's New World Dictionary
 

For the week beginning February 13, 2000

Flash’s Astronomical Fact #17

During the Renaissance, wealthy merchants and members of the nobility were among the few people who had both the time and the money to indulge their passion for astronomy. Some of these amateur astronomers made important contributions. Danish nobleman Tycho Brahe (1546-1601) observed the night sky for thirty-five years. More importantly, he used measuring instruments of his own design to plot accurately the positions of the heavenly bodies he observed - particularly the planet Mars. More importantly still, he kept meticulous records of his observations. By analyzing Tycho's data, Johannes Kepler (1571-1630) was able to develop his Three Laws of Planetary Motion.

 Sources: Cosmos by Carl Sagan, Webster's New World Dictionary, and the Brahe's Quadrant site at http://broccoli.caltech.edu
 

For the week beginning February 6, 2000

Flash’s Astronomical Fact #16

In the previous edition of Flash's Astronomical Facts, I recounted the 1908 Tunguska Event: A tremendous explosion that occurred in the sky above a sparsely populated region of Central Siberia. The apparent cause of the Tunguska Event was a massive object from deep space that entered our atmosphere and exploded just above ground level. The force of the detonation wreaked incredible - and incredibly widespread - devastation.

But what was the nature of this object? What messenger from beyond could cause such horrific destruction? Speculation has run the gamut from an asteroid to an errant piece of antimatter to a miniature black hole to the crash of an alien spaceship. But the consensus opinion - and the only explanation consistent with most (though admittedly, not all) of the evidence - is a comet: A heavenly body composed primarily of ice and dust. Scientists surmise that such an iceball, as a consequence of plunging through the Earth's atmosphere, would have become superheated due to air friction. This in turn would have caused it to detonate spontaneously.

Could another comet of similar size and composition create another disaster comparable in destructive force to the original Tunguska Event? With the comet exploding this time not over a remote region, but over a major city? The Tunguska Event did happen, so collisions with comets are not impossible. Keep watching the sky! 

 Sources: Cosmos by Carl Sagan and the Tunguska Event site at http://www.galisteo.com
 

For the week beginning January 30, 2000

Flash’s Astronomical Fact #15

In the early morning hours of June 30, 1908, a fiery object was seen hurtling towards the Earth over a remote region of Central Siberia. It left in its wake a light trail an estimated 800 kilometers long. The object, a visitor from deep space, is estimated to have been 100 meters in diameter and to have weighed at least 100,000 tons. It plunged into our atmosphere at an estimated 30 kilometers per second, and exploded a mere 7.6 kilometers (estimated) above the planet's surface. 

The force of the detonation, estimated to have been the equivalent of 40 megatons of TNT, produced Earth tremors that were detected thousands of kilometers from "ground zero". The atmospheric shock wave created by the blast circled our planet not once, but twice. Forests beneath the explosion burned for weeks, producing a column of fire that was visible for several hundred kilometers. Herds of reindeer simply vanished, never to be seen again. Several of the region's few human inhabitants suffered injuries; some as a consequence of being tossed through the air like rag dolls by the force of the blast. Eyewitness accounts related by the indigenous Tungus people make for fascinating - and frightening - narrative. The Tungus interpreted the occurrence to be the act of a displeased god. Believing that the area had suffered some kind of enchantment, they declared it off-limits.

It was not until 1927 that the first scientific expedition arrived on the scene to survey the area. When geologist Leonid A. Kulik and his team reached the so-called "enchanted region", they beheld an incredible sight. Thousands of stately trees, bereft of their leaves and branches, had been blown down like so many matchsticks. The trees pointed outwards from ground zero in a radial pattern, like the spokes on a bicycle wheel. In all, over 2,000 square kilometers - an area about 2/3 as large as the state of Rhode Island - had been completely devastated.

Because the explosion took place over a region called Tunguska, the incident is referred to as the Tunguska Event.

But what was the exact cause of the Tunguska Event? We will examine that question in the next edition of Flash's Astronomical Facts. 

 Sources: Cosmos by Carl Sagan and the Tunguska Event site at http://www.galisteo.com
 

For the week beginning January 23, 2000

Flash’s Astronomical Fact #14

The Great Red Spot is the name given to the immense cyclonic storm visible in the upper reaches of Jupiter's atmosphere. It was first observed in 1655 by Italian-French astronomer Jean-Dominique Cassini (1625-1712). It has been raging continuously since at least that time. The hurricane-like vortex rotates counter-clockwise. Its outermost edges complete a full cycle every six days (interestingly, Jupiter itself completes one rotation every ten hours).

And just how great is the Great Red Spot? It varies in size from between two to three times as large as the Earth! That great enough for you?

 Sources: The Cassini site at http://galileo.imss.firenze and The Great Red Spot site at http://antwrp.gsfc.nasa.gov
 

For the week beginning January 16, 2000

Flash’s Astronomical Fact #13

The Sun shines continuously on the Earth, and so our planet casts continuously a shadow on the side opposite. Because both the Sun and the Earth are large bodies and not single points, the shadow consists of two distinct zones. On the side directly opposite the Sun, there lies a cone of darkness called the umbra. Surrounding the umbra is a region of relatively lighter shadow called the penumbra.

During the total lunar eclipse that will occur on January 20, 2000, you will be able to see (weather permitting) how much variance there is between these two zones. The Earth will pass directly between the Sun and the Moon, throwing its shadow over our satellite world. The Moon will start out sporting its typical bright, silvery color. When the Moon enters the penumbra of the Earth's shadow, it will turn a dull reddish-brown. When it is within the umbra, it will turn a bright reddish-orange. Later in the evening, it will move once again into the penumbra, once again becoming a dull reddish-brown. Finally, it will leave the Earth's shadow altogether, once again taking on its familiar bright, silvery appearance.

Devout skywatchers will sit on a lawn chair and observe the Moon for the entire five and one-half hour duration of the eclipse. But one might find it more illuminating (no pun intended) to watch the Moon for just a couple of minutes at twenty to thirty minute intervals. In this way, the color changes may be more obvious. 

 Sources: Star Date magazine Sky Atlas 2000 and Webster's New World Dictionary
 

For the week beginning January 9, 2000

Flash’s Astronomical Fact #12

The ancient Romans seemed to have a god for everything under the sun - including the sun. Janus was a minor Roman god in charge of portals, a task for which he was particularly well suited. For you see, he had two faces - one looking forward, and the other looking backward. Or, symbolically, one looking ahead into the future, the other looking behind into the past. Small wonder then that this god became the source of the name for the first month of the year: January!

 Source: Webster's New World Dictionary
 

For the week beginning January 2, 2000

Flash’s Astronomical Fact #11

It is now the year 2000. It is a new year… but it is NOT a new millennium.

I hate to rain on anyone's parade, but the truth is the truth. 2000 is NOT - I repeat - NOT the first year of the third millennium. It is the last year of the second millennium.

How so, you ask? It has to do with the way years are counted. You see, though it is hard to believe, THERE IS NO YEAR ZERO! The sequence of years goes like this: … 3 BC, 2 BC, 1 BC, 1 AD, 2 AD, 3 AD ...

As a result, the counting begins with one, not zero. 1 was the first year of the first millennium. 1001 was the first year of the second millennium. And 2001 will be the first year of the third millennium. Live it, love it, learn it, get used to it.

Like I said, I do not wish to be a wet blanket; but a falsehood popularly believed to be true is still a falsehood. Moreover, in what sort of world would we be living if those who know the truth felt too intimidated by popular opinion to speak the truth?

Besides, look on the bright side. Come December 31, 2000, we can have another blowout - without all the Y2K hype. Things could be worse.

 Source: The millennium site at http://greenwich2000.co.uk
 

For the week beginning December 26, 1999

Flash’s Astronomical Fact #10

Have you ever stood by the railroad tracks while a train sped past? Did you notice how the sound of the train's whistle seemed to rise in pitch as the train approached and drop in pitch as the train receded? The reason this happens is because the whistle - as the consequence of being attached to the train - is in motion. When the source of the sound is moving in the same direction relative to the sound waves, those sound waves become compressed and the pitch rises; conversely, when the sound source is moving in the direction opposite the sound waves, those sound waves spread out and the pitch falls. Austrian physicist Christian Doppler (1803-1853) was the first to give (in 1842) the correct explanation for this phenomenon. Hence, it is called the Doppler effect.

The Doppler effect applies also to waves of light. When an object in deep space is moving away from the Earth, the light from its spectral lines shifts towards the lower frequency or red end of the spectrum; conversely, when an object is moving towards the Earth, the light from its spectral lines shifts towards the higher frequency or violet end of the spectrum. By means of these red shifts and violet shifts, astronomers can determine whether an object is moving towards or away from the Earth; and, by the degree of shift, at what rate of speed.

 Source: Understanding Physics by Isaac Asimov 
 

For the week beginning December 19, 1999

Flash’s Astronomical Fact #9

The first attempt to calculate the circumference of the Earth was accomplished astronomically. Eratosthenes (275-195 B.C.) noted that at noon on the summer solstice, the Sun's rays shone directly down a vertical well in the city of Syene, in southern Egypt. But on that same day next year in the city of Alexandria, in northern Egypt, he noted that a vertical stick cast a shadow of a little over 7 degrees (about 1/50 of a 360 degree circle). Eratosthenes hired a man to pace off the distance between Syene and Alexandria. Eratosthenes reasoned that, if the distance between Syene and Alexandria corresponds to 1/50 of the Earth's circle, then 50 times that distance must represent the totality of the Earth's circumference.

Of course, trying to measure a distance of several hundred miles by walking steps is inherently inaccurate. Eratosthenes compensated for this by including an error factor in the final result (as it turns out, he included more error factor than was actually needed). Eratosthenes' calculation of the circumference of the Earth: 28,750 miles, compared to the true measurement of 24,902 miles at the equator.

Erastothenes must not be faulted for being several thousand miles off. His idea was conceptually sound, and any errors were mostly the consequence of the inaccurate measuring methods and instruments of his day. Though he was more than 15% over the true measurement, it was several centuries before anyone came up with a more accurate result.

By observing that the Sun's rays do not fall at the same angle everywhere on the Earth, Eratosthenes established incontrovertibly that the world is not flat. But the notion of a round Earth would not be generally accepted as fact for many centuries. 

 Source: Cosmos by Carl Sagan, Webster's New World Dictionary and the Erastothenes site at http://maps.unomaha.edu
 

For the week beginning December 12, 1999

Flash’s Astronomical Fact #8

Hold an index finger upright at arm's length. Now, hold your right eye open and close your left; then, hold your left eye open and close your right. Notice how the position of your finger shifts relative to the background? The shifts are caused by the slightly different angle of sight from each eye. This effect is called parallax.

By applying this same principle on a much larger scale, scientists were able to determine the distances to the nearby stars. Astronomers noted the relative positions of the stars on a certain day of the year. Six months later, when the Earth was on the opposite side of its 186,000,000-mile diameter orbit, the relative positions of the stars were noted again. The scientists found that the positions of several of the stars had shifted relative to the positions of the stars in the background. The shifts were nominal, but definite - and measurable.

With the degree of angular shift of a given star thereby determined, all that is needed to calculate the distance to that star is some applied trigonometry. Thus, this method of measuring the distance to the stars is called trigonometric parallax.

This method has its limits. It is accurate only for stars within 200 light-years of Earth. Beyond that, the angles become too small to measure accurately. Other techniques had to be devised to determine the distances to the farther stars. Those techniques will be explained in future editions of Flash's Astronomical Facts.

 Source: Voyage Through the Universe/Atlas, a Time-Life book series
 

For the week beginning December 5, 1999

Flash’s Astronomical Fact #7

Since ancient times, people have looked to the stars for guidance. When the stars were unfavorable (by whatever criteria), bad happenings (conquest, famine, pestilence, etc.) were said to follow. Thus, another word for catastrophe came into being, a word that - literally translated - means "ill-starred": Disaster!

 Source: Webster's New World Dictionary
 

For the week beginning November 28, 1999

Flash’s Astronomical Fact #6

You can use your fingers and hands to estimate the size of objects in the night sky.

An adult's pinky finger, held upright at arm's length, covers about one degree of the sky. More than enough to cover the full moon.

An adult's fist, held upright at arm's length, covers about ten degrees of the sky. About the width of the upper part of the bowl of the Big Dipper. 

The span from the tip of the thumb to the tip of the pinky finger of an adult's fully spread hand, held at arm's length, covers about twenty degrees of the sky. About the size of the Northern Cross, the principal asterism of the constellation Cygnus (The Swan).

And here's a bonus for you fans of the University of Texas at Austin. The "Hook 'em Horns" sign, held at arm's length, covers about fifteen degrees of the sky. A little larger than the "W" or "M" portion of the constellation Cassiopeia (The Lady in the Chair).

 Source: Voyage Through the Universe/Atlas, a Time-Life book series and The National Geographic Society's Map of the Heavens
 

For the week beginning November 21, 1999

Flash’s Astronomical Fact #5

The element helium is named for Helios, the Greek god of the Sun. Appropriate. Spectroscopic analysis conducted during the solar eclipse of 1868 revealed the presence in the Sun of the previously unknown element. It was not until 1895 that helium was found to exist on the Earth.

 Sources: CRC Handbook of Chemistry and Physics and Webster's New World Dictionary
 

For the week beginning November 14, 1999

Flash’s Astronomical Fact #4

The U.S. Viking I Mars lander was scheduled to touch down on the Red Planet on July 4, 1976, as part of the American Revolution Bicentennial celebration. Unfortunately, examination of the proposed landing zone revealed that it was unacceptably risky as a touchdown site. Undaunted, NASA established a new touchdown site and rescheduled the landing for another anniversary date: July 20, 1976, seven years to the day after the first Moon landing. 

 Source: Cosmos by Carl Sagan 
 

For the week beginning November 7, 1999

Flash’s Astronomical Fact #3

The ancient Romans referred to the first day of every month as the calends. This is the source of the word calendar.

 Source: Webster's New World Dictionary
 

For the week beginning October 31, 1999

Flash’s Astronomical Fact #2

The Sun rises in the east and sets in the west. Thus, in the northern hemisphere, the shadow cast by a sundial's indicator progresses from left to right throughout the day. When mechanical clocks were invented, the hands were made to turn in conformance with this familiar pattern. In other words, the Sun is the reason that clocks run… clockwise.

 Source: Why Do Clocks Run Clockwise? and other Imponderables by David Feldman
 

For the week beginning October 24, 1999

Flash’s Astronomical Fact #1

Many ancient cultures were aware of the existence of solstices and equinoxes, which mark the first day of a season. The old Celtic calendar went a step further and gave special significance also to the days marking the midpoints of each season. Because each season takes up a quarter of the calendar, these midway points were called cross-quarter days. The cross-quarter days are February 2, May 1, August 1, and November 1.

November 1 was for a holiday known as Samhain, the first day of the year on the old Celtic calendar. But Samhain was much more than just New Year’s Day. On Samhain, the souls of the departed were said to rise and walk among the living. Samhain thus became known also as All Saints’ Day or All Hallows’ Day, a day for honoring dead ancestors. The day preceding it, October 31, was used for making preparations for Samhain. It became - and still is - an important holiday in its own right. It is called All Hallows’ Eve, more popularly known as… Halloween.

 Data from website http://members.thebee.net/lsspin/celticworld