Mimas is the seventh of Saturn's known satellites, orbiting some at a distance of about 115,300 miles. It has a diameter of 244 miles and weighs 3.8x10^19 kg.
When Voyager 1 visited in 1980, it sent back an image showing a large impact crater called Herschel that makes Mimas look uncannily like the Death Star.
See http://pds.jpl.nasa.gov/planets/jpeg/sat/mimas.jpg for an image of this moon.
Mimas's orbit and gravity makes a gap in Saturn's rings, pulling all ring particles at integer fractions of its own orbit - see http://www.jpl.nasa.gov/cassini/english/pic/images/astro/image8.jpg.