In September 2005, the Cassini spacecraft captured this image of Dione, Saturn’s fourth-largest moon, dwarfed by the planet in the background. Rings cast shadows on the subtle, warmly colored cloud bands in Saturn’s northern hemisphere. The blue color is believed to result, as on Earth, from enhanced scattering of sunlight by a clear upper atmosphere made free of extensive cloud cover by the cold of winter. This natural-color view of the yellowish planet combines images taken by Cassini’s wide-angle lens with red, green, and blue filters. At the time, the spacecraft was about 800 000 kilometers from Dione, which is 1118 kilometers in diameter and orbits approximately 377 000 kilometers from the planet. (Image courtesy of NASA/JPL/Space Science Institute.)
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