The "Dagwood Sandwich" Moon. Earlier models of Ganymede's oceans were based on the assumption that the existence of salt didn't change the nature of liquid very much with pressure. However, Dr. Vance and his colleagues found, through laboratory experiments, that salt does increase the density of liquids under the extreme conditions hidden deep within Ganymede and similar icy moons with subsurface bodies of water. Imagine adding table salt to a glass of water. Instead of increasing in volume, the liquid will actually shrink and become denser. The reason for this is that salt ions lure water molecules. Dr. Thomas and his team at Cornell University have tried to peer into the mysterious interior of the weird little Space egg that is Methone. They started out with the hypothesis that Saturn's relentless strong gravity pulls the little moon into an elongated shape, just like Earth's own large Moon raises ocean tides on our own planet. Then the team went on to calculate how dense the little moon would have to be for its own gravity to counteract those intense tidal forces and create its strange egg-shape. Jupiter is the fifth planet from our Star, the Sun, and it is more than twice as massive as all of the seven other major planets combined! Its immense mass weighs-in at an incredible 318 times that of the Earth.