Ice World Tethys
This image of Saturn's icy moon Tethys was captured by NASA's Cassini spacecraft on April 11, 2015. It shows differences in color on the moon that may be caused by subtle differences in the composition or crystal size of the icy material that makes up the moon's crust. The large crater visible to the right of center is Odysseus crater, which measures 280 miles across. Tethys is believed to be composed almost entirely of water ice.
NASA / JPL / Space Science Institute