Rhea is Saturn's largest satellite discovered in 1672 by Giovanni Cassini. The moon is icy and has a low density of 1.33 g/cm3. It probably has a rocky core that makes up about 1/3 of the Rhea's mass with the rest of the material to be water-ice. Rhea bears resemblance to Dione in their composition, albedo and terrain.
The surface of Rhea is heavily cratered. Generally, there are two major geological classifications for the types of craters on the surface. The first classification are for the craters larger than 40 kilometers in diameter (25 miles) and the second classification is for the craters less than 40 kilometers in diameter (25 miles). This evidence indicates the possibility of a surface REsurfacing that took place sometime in its history.