Saturn's Cleanest Moon: Enceladus.

Enceladus orbits Saturn between the smaller Mimas and the larger Tethys . Enceladus is composed mostly of water ice and has the cleanest and purest ice surface in the Solar System . It's surface therefore appears nearly white. The surface also has many unusual groves and relatively few craters, like Jupiter 's moon Ganymede . This indicates that the surface is young and/or newly reformed. To explain this, some astronomers speculate that Enceladus is susceptible to some sort of volcanic activity. Enceladus was originally discovered in 1789 by William Herschel .