Methone: 3-kilometer diameter Smooth Egg Moon of Saturn - Why is this moon shaped like a smooth egg? The robotic Cassini spacecraft completed the first flyby ever of Saturn's small moon Methone in May and discovered that the moon has no obvious craters. Craters, usually caused by impacts, have been seen on every moon, asteroid, and comet nucleus ever imaged in detail -- until now.
Moons of Saturn : Janus Discovery News Janus is a tiny, potato-shaped satellite that is typical of Saturn's 17-plus moons: cratered and icy. It's the big brother to the moon Epimetheus, which hangs out in nearly the same orbit. By studying Cassini spacecraft images closely, scientists have noticed both moons hang out in a thin but wide ring of dust and ice -- likely the leftovers of meteorite impacts over the eons. CREDIT: NASA/JPL/SPACE SCIENCE INSTITUTE