That world was one of Saturn’s many moons, Rhea. The discovery of Rhea took place on December 23, 1672 by Italian astronomer, mathematician and engineer Giovanni Cassini. Rhea was the second of ...

On Dec. 23, 1672, Italian astronomer Giovanni Cassini discovered Rhea, Saturn’s second-largest moon. Rhea is made up of rock and ice and is covered in craters. Rhea is also the only moon ...