DISCOVERY OF SATURNS SECOND LARGEST MOON; DEC 23, 1672.
Photo By: NASA/JPL Cassini Spacecraft: CLICK photo to view full size and look below for links and info.
On December 23, 1672 Giovanni Domenico Cassini discovered Saturn’s second largest moon, Rhea, one of the most heavily cratered satellites in the solar system. In this photo you can notice two very large impact basins. At upper right is Tirawa and just to its immediate low left is Mamaldi.
There are a couple key points to make here; this photo is of Rhea’s anti-Saturnian side which means that; like our Moon, Rhea only shows one side to Saturn ever. In fact, of the 62 moons of Saturn, 16 are tidally locked in this fashion.
NASA Solar System page for Rhea: http://solarsystem.nasa.gov/planets/profile.cfm?Object=Rhea
NASA/JPL Cassini page for Rhea: http://saturn.jpl.nasa.gov/science/moons/rhea/