Each of the little Space eggs resides within its own ring arc--which is a fragmentary ring of Saturn. One hypothesis states that glittering ice crystals swarming around in the ring arc might be floating down to the surface of Methone, filling in its impact craters or other rough topography. This is something that is thought to have occurred on two other small, icy moons of Saturn--Atlas and Pan. Icy stuff swarming around in Saturn's rings apparently piled up around each moonlet's equator.
Europa: Planetary scientists generally think that a layer of liquid water swirls around beneath Europa's surface, and that heat from tidal flexing causes the subsurface ocean to remain liquid. It is estimated that the outer crust of solid ice is about 6 to 19 miles thick, including a ductile "warm ice" layer that hints that the liquid ocean underneath may be 60 miles deep. This means that Europa's oceans would amount to slightly more than two times the volume of Earth's oceans.
GRAIL Mission Puts A New Face On The Moon! Scientific investigation into the origin of lunar impact basins has been hampered because there is a general lack of agreement on their size. The majority of the largest impact basins pock-mark the near-side of the Moon (the Moon's enchanting "face"), and have also been filled in by gushing lava streams. These lava streams have covered up, and rendered invisible, important clues pertaining to the shape of the land.