One of Saturn’s moons, Dione, has joined the ranks of our solar system’s “ocean worlds”—icy moons or planets with oceans beneath their crusts, Astronomy Now reports. (Three ocean worlds orbit Jupiter, three orbit Saturn, and Pluto could also belong to the club.) The discovery is thanks to gravity data from a flyby by NASA’s Cassini spacecraft, which also discovered the subsurface oceans of two others of Saturn’s moons, Titan and Enceladus. The researchers who reported this finding in Geophysical Research Letters say Dione’s ocean has existed since the moon’s origin, which increases the chances that microbial life is thriving in its waters.
*Correction, 6 October, 4:02 p.m.: An earlier version of this article incorrectly stated that Saturn has seven moons. It also incorrectly stated that a subsurface ocean was in definite existence on Dione. The article has been corrected.