Rhea

Rhea is Saturn's second-largest moon. It is about half of the size of Jupiter's Galilean moons, at 930 mi (1530 km) in diameter. Rhea orbits Saturn at an average distance of about 325,000 miles (524,000 km). It is bright enough to be seen in amateur-sized telescopes, and was discovered by Giovanni Cassini in 1672.

Rhea's trailing hemisphere shows wispy terrain. Extreme false color makes it clear that the wisps - likely networks of fractures similar to those on Dione - cut across older, cratered terrain. Rhea has a low density, so it probably has only a small rocky core. Rhea is also tidally locked with Saturn and shows dissimilarities in it leading hemisphere and its trailing hemisphere, much like Iapetus and Dione. In fact, Rhea also shows bright wispy streaks on it trailing hemisphere first seen on Dione. Rhea and Dione are similar in composition, terrain, albedo, and synchronous rotation.