Ganymede: Moonquake World . ... Credit Copyright: NASA , Voyager , Copyright Calvin J. Hamilton Explanation: Ganymede probably undergoes frequent ground shaking events not unlike terrestrial earthquakes. Ganymede , the largest moon of Jupiter and the Solar System , has a thick outer coating of water ice. ... Ganymede was discovered by Galileo and Marius in 1610, and is larger than the planets Mercury and Pluto. The NASA spacecraft Galileo is scheduled to arrive at Jupiter is December of 1995. ...