Tethys 

Tethys is an icy moon discovered by Giovanni Cassini in 1684. It is very similar to Dione and Rhea and has a density of 1.21 g/cm^3. This means that most of the satellite is made of water-ice. The surface has many craters and cracks, the result of repeated pummeling of meteorites s well as surface activity.

One landmark on the surface is the Ithaca Chasma that extends three-fourths around Tethys' circumference and is 65 kilometers (40 miles) wide. Many other younger trenches like this exists on the surface. The temperature is measured to be -187° C (-305° F).

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.