Dione

Like most of Saturn's large moons, Dione contains large amounts of water ice. The craters, however, show no signs of erosion. The temperature on the moon is -187 °C — so low that the icy surface does not move, behaving much like rock. Dione shares its orbit with two other, smaller moons. One of these Trojan moons flies 60° ahead of Dione, while the other follows 60° behind.