Looking for a sky event this week? Check out our full Sky This Week column. November 19: Venus rises in Libra Tonight, all ...

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 ...

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 ...

Share on Facebook (opens in a new window) Share on X (opens in a new window) Share on Reddit (opens in a new window) Share on Hacker News (opens in a new window) Share on Flipboard (opens in a new ...

The predawn hours of Aug. 8 present a perfect opportunity to see Jupiter's four largest moons line up next to the "King of the Planets" as it voyages through the stars of the constellation Gemini.

Through a vast ocean, Jupiter's moon Europa is an exciting target for research in the search for life. Two space probes are ...

Callisto, Jupiter's second-largest moon, may have a rocky surface with an ocean beneath the surface. If there was a contest for the most interesting moon in our solar system, Callisto would be a ...