How many moons does Saturn have? So far 62 have been discovered, the smallest only a fraction of a kilometer across. Six of its largest satellites can be seen here, though, in a sharp Saturnian family portrait taken on March 9, 2012. Larger than Earth’s Moon and even slightly larger than Mercury, Titan has a diameter of 5,150 kilometers and starts the line-up at the lower left. Continuing to the right across the frame are Mimas, Tethys, [Saturn], Enceladus, Dione, and Rhea at far right. Saturn’s first known natural satellite, Titan was discovered in 1655 by Dutch astronomer Christiaan Huygens, while most recently the satellite provisionally designated S/2009 S1 was found by the Cassini Imaging Science Team in 2009.