The Silent Ice Moons: Callisto, Tethys, Dione, Iapetus, and Smaller Moons of the Outer Giants
The gas and ice giant worlds each have an extensive family of satellites, but with one exception, each has only a handful of large, complex moons (Fig. 5.1). Jupiter has its four Galilean satellites, Uranus has its five major moons (Ariel, Umbriel, Titania, Oberon, Miranda, and Ariel) and Neptune has its trio of moons: Proteus, Triton, and Nereid. In each case, the rest of the moons range from a few to less than 180 km across. The exception is Saturn. Saturn’s retinue includes so many major moons that educators have come up with a mnemonic to remember them: MET DR THIP (for Mimas, Enceladus, Tethys, Dione, Rhea, Titan, Hyperion, Iapetus, and Phoebe).