This image of Rhea was acquired by the Voyager 1 spacecraft on November 11, 1980. Rhea 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 grams per cubic centimeter. 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 -1740C in direct sunlight and between -2000C and -2200C in the shade.
Date: 11 Nov 1980
Rhea is heavily cratered with bright wispy markings. Its surface can be divided into two geologically different areas based on crater density. The first area contains craters larger than 40 kilometers in diameter. The second area, in parts of the polar and equatorial regions, has craters under 40 kilometers in diameter. This suggests that a major resurfacing event occurred sometime in the moon's past.
Image Credit: Jet Propulsion Laboratory, NASA
Credit: NASA Planetary Photojournal