Astronomers have uncovered new evidence that Jupiter’s moon Callisto likely harbors a massive underground ocean, potentially joining Europa and Ganymede as another water-rich world in the outer ...

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 ...

Jupiter's Callisto is the third-largest moon in the solar system, featuring deep craters that reveal fresh ice beneath, spreading bright ejecta debris across its rugged surface. Io, the innermost ...

Ganymede, Jupiter's largest moon and the solar system's largest, is bigger than Mercury and the dwarf planet Pluto, with a diameter of 5,268 kilometers.