Tidal Dynamics of Moons with Fluid Layers: From Ice to Lava Worlds

In the last fifty years, the spacemissions Voyager, Galileo, Cassini-Huygens and Juno explored the moons of the outer Solar System and revealed a wide spectrum of worlds. While some of these worlds are barren, others are among the most geologically active of the Solar System. The innermost Jovian moon, Io, showcases spectacular volcanic activity; its three companions, Europa, Ganymede and Callisto, are likely ocean worlds that harbour subsurface oceans beneath their icy crusts. Similarly, the biggest Saturnian moon, Titan, is believed to have a subsurface ocean concealed beneath its icy surface and dense atmosphere. Saturn’s collection of smaller icy bodies feature different levels of activity, Enceladus being the most remarkable. Above its limb, water plumes rise more than hundred kilometers spilling its internal ocean into Saturn’s E-ring. In Neptune, the captured moon Triton orbits in a peculiar retrograde orbit; its barely cratered surface is similar to that of other ocean worlds and shows signs of cryovolcanic activity. The spectrum of geological activity displayed by the moons of the outer Solar System is thought to bemainly the consequence of tides.