We have known about the water on Enceladus for a while now. Hydrothermal vents at its southern pole shoot water vapor into space, high enough and big enough to be seen hundreds of thousands of miles away. But now, thanks to some clever analysis of the wobble in its orbit around Saturn, we now know something else about it: that water comprises an ocean that spans the entire globe, just under its solid crust.
NASA worked out the answer to the puzzle of whether Enceladus had a global ocean using research from Cassini, a spacecraft launched in 1997 that arrived at Saturn in 2004 and has spent the last decade studying the planet and its many moons.
Enceladus isn’t the only worldlet in our Solar System that jets liquids from its surface, and once Cassini arrived in orbit around Saturn it was to confirm that the moon was spouting water. But while there had been suspicions that Enceladus had a subsurface sea, nobody really knew for sure how big that sea was. In this latest study of the gathered data, however, the researchers noticed a wobble in its orbit that “can only be accounted for if its outer ice shell is not frozen solid to its interior.”
In other words, Enceladus sloshes.