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 | | First Return to Xanadu - These false color infrared images from December 10-11, 2004, show the approach to Titan for the December 13 encounter. They are each composed of three infrared pictures (Continuum band 3 at 938 nanometers, IR Broadband 3 at 928 nanometers, and Methane Band 2 at 727 nanometers) displayed as red, green, and blue, respectively. Colors are balanced to bring out the surface features while still showing the higher hazes as blue. The bright pinkish feature is Xanadu, the first "Titanic" feature identified from Earth. The bright streak in the top image is a cloud in the southern temperate zone. |
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 | | Solar Eclipse - This color image shows Titan's atmosphere lit from behind. The images used to compose it were taken hours after Cassini had passed Titan on December 13, 2004. Looking back at the moon, we see sunlight scattered back through the atmosphere. The Sun is behind Titan, and this is similar to what we would see if we looked at Earth from the Moon during a lunar eclipse, when the Moon is in Earth's shadow. |
 | | Distant Sunset in Many Colors - Green-Ultraviolet - This and the following three narrow angle camera images show a part of the eclipse image above, actually taken a short while earlier. The images are in "Geordi Vision". Geordi LaForge, the character from Star Trek - The Next Generation had a multispectral visor and neural interface that allowed him to see in colors ordinary people cannot. The first image spans the range from green to ultraviolet, the second is approximately true color (red to blue), the third is infrared to red, and the fourth is infrared. They all look similar in color because the colors "seen" by the camera on Cassini are shifted into the red, green, and blue we see. The first image shows the ultraviolet (seeming blue) hazes in the upper atmosphere. As the "color window" is shifter toward the infrared, the colors become more muted and appear lower in the atmosphere. This is because longer wavelengths scatter deeper into the atmosphere and come out more mixed and farther away from the horizon. We are familiar with this phenomenon on earth as the continuing reddening of the sunset as the sun appears to move over the horizon. The filters used in the first image are 569 nm (green, colored red in the image), 441 nm (blue, colored green), and 343 nm (UV, colored blue). |
 | | Distant Sunset in Many Colors - Natural Color - The filters used in the first image are 649 nm (red), 569 nm (green), and 441 nm (blue). |
 | | Distant Sunset in Many Colors - Infrared-Red - The filters used in the first image are 861 nm (infrared, colored red in the image), 750 nm (infrared, colored green), and 649 nm (red, colored blue). The upper level hazes have mostly disappeared in these colors. |
 | | Distant Sunset in Many Colors - Infrared - The filters used in the first image are all infrared: 928 nm (colored red in the image), 861 nm (colored green), and 750 nm (colored blue). |
 | | Space Art in the Real - This near true color image fron December 14, 2004, shows a view of Saturn formerly only seen in space art. Since the Earth is very near the Sun as far as Saturn is concerned, we cannot see much of the ring shadow, it being mostly hidden behind the rings. From Cassini's perspective, however, the ring shadow is revealed in all its complexity, cast from below by the Sun, which is behind and "below" the spacecraft point of view. The shadow of the inner part of the rings is at bottom, with she shadow of the outer rings being at the top. The Cassini division is the large lower bright band, and the Encke Division is the upper, smaller band. The blue color is caused by the fact that light hits the atmosphere obliquely coming in from the Sun then coming back out to the spacecraft. Just like on Earth, you see a lot of blue sky this way, since the light must pass through so much of it. Saturn must have extreme seasons. Not only is the northern hemisphere (top) tilted away from the sun, but a lot of it is also hidden in ring shadow. (The missing black square is a place where there was no images returned. Cloud features cannot be seen because the original images were relatively low contrast, and the clouds on Saturn lie beneath a layer of haze.) |
 | | Circumpolar Clouds and Dione - This mosaic is produced from images taken on December 14, 2004, in the 889 nm infrared methane filter. This renders the upper atmospheric hazes more transparent so the clouds beneath them can be seen. The image itself is partly artificial. The spacecraft moved significantly between frames, as did the clouds, so a good deal of artificial patching had to be done to make a clean mosaic. The moon Dione is visible in front of the clouds. It was very overexposed in the original, hence was replaced by an image in the 727 nm methane filter. |
 | | Circumpolar Clouds and Dione in Color - This is the near true color composite made from images taken at the same time as the image above. In color, the cloud bands are more subdued, but small storms can be seen. They're relatively small, anyway. Dione only looks bigger because it is much closer. Note that the moon has almost no color, which creates the unusual impression of a black and white image being superimposed on a color one. An image made at NASA (apparently from the UV image and others containing Dione) is located here at the NASA Photojournal. This one here was made by combining images taken through the red, green, and blue filters and color balancing to match my own impressions of the color of Saturn, plus colors in some of the more well considered Voyager images (meaning images whose source discusses how they attempted to produce correct color). Like the above image, some artifice had to be used to blend the images and remove some artifacts from the originals. |
 | | Postcard from Saturn - This is simply a section from the above image, contrast enhanced so the colors appear like they might in a panoramic postcard like you can get at tourist sites on Earth. |
 | | Dione Blues - This false-color image from December 15, 2004, is made from green and two ultraviolet images of Dione. The green at 569 nm is colored red, 343 nm UV is colored green, and 264 nm UV is colored blue. The dark "halo" around the fissures on the left side of the image is even darker in UV, so it shows up relatively orange (which is to say, visible grey as opposed to UV). These color distinctions do not show up in visible light. The image was also color balanced so the blues show up more, they being relatively dark in the original image. Differences in color in this image, as in any other image (or thing seen with the eyes), is caused by a difference in the ratio of the amount of light in each of the separate filters (or in the three types of color-sensitive cones in the eyes). If we had green, UV343, and UV264 cones instead of red, green, and blue cones, this is something like what we would see when we looked at Dione. As for what made the fissures and non-UV region on Dione. . . I haven't figured that out yet. |
 | | Dione Close-up - This mosaic of visible light images from December 15, 2004, is a high resolution picture of a part of Dione around behind the lower left limb of the image above. The resolution is about one half of a kilometer per pixel. Here you can see that what appear like whispy streaks in more distant images are several complexes of roughly parallel fissures. Note also the linear crack near the center of the mosaic. The NASA version of this mosaic is located here at the NASA Photojournal. My mosaic merges the upper two images better. Theirs has data to the right with compression artifacts removed, which mine does not. The Dione feature naming convention is Virgil's Aenead. The large crater at lower left is called Dido. The parallel cracks near center (with the straight crack cutting them, begging to be called Scipionis Linea) is called Carthage Linea. |
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