Mimas 

Mimas was discovered by William Herschel in 1789 and is one of the innermost moons of Saturn. It has an icy surface with many craters with a low surface temperature of about -200° C (-328°F). Its low density indicates that most of the moon is composed of ice.

Mimas has enormous impact craters with one measuring the size of 130 kilometers (80 miles) wide. This crater is called the Herschel and it extends one-third the diameter of Mimas! The crater is 10 kilometers high (6 miles) and has a central mountain as high as Mount Everest on Earth.

The larger cratering of the surface (greater than 40 kilometers: 25 miles) occurs almost everywhere except in the south polar region. In that region most craters are relatively small with the largest being 20 kilometers (12 miles), possibly the result of some surface activity.

Physical Data Key Mass Mass Mass Mass compared to that of Earth. Radius Radius Radius Radius compared to that of Earth. Mean Density Average Density. Distance Distance to the planet's center. Magnitude The brightness of a star or object.

Orbital Data Key Rotational Period Number of days to make one complete rotation. Orbital Period Number of days to obital the planet. Mean Orbital Velocity Average obital speed. Orbital Eccentricity Eccentricity. Orbital Inclination The tilt of the moon or planet. Escape Escape Velocity. Albedo Visual geometric albedo.