This global colour mosaic of Dione’s intriguing surface was produced from images taken by the international Cassini spacecraft during its first 10 years of exploring the Saturn system.
Perhaps the most striking observation is the difference in colour and brightness between the left and right halves of the image. They correspond to the ‘trailing’ and ‘leading’ hemispheres respectively, in terms of the direction that the moon is travelling along its orbit around Saturn every 2.7 days.
The dark coating on the trailing hemisphere is thought to be due to radiation from Saturn’s magnetosphere, which causes organic elements in the moon’s surface to become darker and redder in appearance.
The wispy white streaks that wind through the coloured surface are bright ice cliffs – some several hundred metres high – resulting from tectonic fractures.
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