Saturn: Moons: Rhea

This image of Rhea was acquired by the Voyager 2 spacecraft on August 25, 1981.

Rhea [REE-a] is the largest airless satellite of Saturn. It was discovered in 1672 by Giovanni Cassini. Rhea is an icy body with a density of 1.33 gm/cm³. The low density indicates that it is composed of a rocky core taking up less than one-third of the moon's mass, with the rest composed of water-ice. Rhea is somewhat similar to Dione. They both have similar composition, albedo features, varied terrain and synchronous rotations. The temperature on Rhea is -174?C with illumation from the Sun and between -200°C and -220°C (-328°F and -364°F) in the shade.

Rhea is heavily cratered with bright whispy markings. Its surface can be divided into two geologically different areas based on crater density. The first area contains craters which are larger than 40 kilometers (25 miles) in diameter. The second area, in parts of the polar and equatorial regions, has craters under 40 kilometers (25 miles) in diameter. This suggests that a major resurfacing event occurred some time during its formation.

Copyright © 1997-1999 by Calvin J. Hamilton.
www.planetscapes.com