Rhea is the second-largest moon of Saturn, known for its icy surface and unique features. It has a diameter of about 1,527 kilometers and is primarily composed of water ice, with a small amount of rocky material. Rhea is notable for its bright, reflective surface and the presence of wispy markings that suggest past geological activity. Discovered in 1672 by the astronomer Giovanni Domenico Cassini, Rhea is one of the many moons that orbit Saturn. It is also believed to have a thin atmosphere composed mainly of oxygen and carbon dioxide. Rhea's intriguing characteristics make it a subject of interest for scientists studying the Saturnian system.