Mimas, the icy Saturnian moon famed for its resemblance to the Death Star, hides a liquid ocean under its crusty surface. The 250 mile-wide object joins Titan and Enceladus (and Jupiter's Europa and Ganymede) in the secret subterranean sea club.
"It's quite a surprise," said Valéry Lainey, an astronomer at the Observatoire de Paris in France. "If you look at the surface of Mimas, there's nothing that betrays a subsurface ocean. It's the most unlikely candidate by far."Peculiarities in Mimas's orbit had led astronomers to entertain two possibilities: either it contained an elongated core shrouded in ice, or an internal ocean that allowed its outer shell to shift independently of the core.By analysing thousands of images from Nasa's Cassini mission to Saturn, Lainey and his colleagues reconstructed the precise spin and orbital motion of Mimas as it looped around the gas giant. Their calculations showed Mimas must possess a hidden subsurface ocean to move the way it does.
Ubi aqua, ibi vita.
Previously: Mimas in Saturnlight