Discovered by Giovanni Domenico Cassini Date of Discovery 1672 Distance from Saturn 527,040 km Radius 764 km Mass 2.31 × 10^24 g Orbital Eccentricity 0.00100 Orbital Inclination 0.35 degree Orbital Period 4.517500436 days Rotational Period Synchronous Density (gm/cm3) 1.33
This icy moon is the largest airless satellite orbiting Saturn. Quite similar to Dione, it is rocky and heavily cratered. What is particularly interesting about Rhea is that based on its low density only 1/3 of its mass, at its core, is thought to be rock. The rest is water ice. Also interesting is that the leading face, as it orbits, is more densely cratered than the trailing face. This suggests a period of melting and refreezing at some point in its history.
Sources: NASA.gov space.com