Add Yahoo as a preferred source to see more of our stories on Google. Callisto, Jupiter's second-largest moon, may have a rocky surface with an ocean beneath the surface. If there was a contest for ...

New evidence from an old NASA mission supports the theory that Jupiter's moon Callisto is in fact an ocean world. Credit: NASA / JPL / DLR A moon of Jupiter about the size of Mercury likely has a ...

What exists beneath the surface of Jupiter's icy moon, Callisto? This is what a recent study accepted by The Planetary Science Journal hopes to address as a team of researchers investigated the ...

If there was a contest for the most interesting moon in our solar system, Callisto would be a contender. Jupiter's second-largest moon has more impact craters on its surface than any other planetary ...