Object Analysis

Rhea is the second-largest moon of Saturn and the ninth-largest moon in the Solar System. It was discovered by Giovanni Domenico Cassini in 1672. It is an icy body with a density about 1.2 times that of liquid water, suggesting it is composed of 75% water ice and 25% rock.

The surface of Rhea is one of the most heavily cratered in the Solar System, similar to the highlands of our Moon. It is divided into two distinct areas: a bright, heavily cratered region and a darker, less cratered region. This "asymmetry" is caused by Rhea being tidally locked to Saturn; one side is always facing the direction of the moon's travel, collecting more impacts.

Rhea is also notable for its "wispy terrain"—bright, thin lines that crisscross its surface. These were long thought to be ice volcanoes but were later revealed by the Cassini mission to be massive tectonic cliffs or "scarps" caused by the moon's crust shrinking as it cooled. It is a quiet, frozen world that has remained largely unchanged for billions of years.