New research suggests the moons of Jupiter and Uranus may hint that our planetary neighborhood once had a third ice giant.

Ganymede may generate its magnetic field through a core that is still forming today, challenging long-held ideas about ...

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.

Jupiter is known as the king of moons. The massive planet has 95 known moons orbiting around it, and some are so large they could almost be considered planets themselves. But what would it actually be ...