Saturn’s moon Mimas, as seen last week by Cassini. This little world, made almost entirely of water ice, is about 400 kilometers across. The innermost of Saturn’s major moons, Mimas zips all the way around the giant planet in just a matter of hours.

Sent by: Cassini | From: Saturn | Sent: Nov, 2008 | Credit: NASA/JPL/SSI | Image source