What is the name of Jupiter's largest moon?

Jupiter’s largest moon is Ganymede. It is the largest moon in the Solar System, even exceeding the planet Mercury in diameter, though its lower density means it has less mass.

Ganymede is one of Jupiter’s four Galilean moons, discovered by Galileo Galilei in 1610. Its icy surface contains two major types of terrain: dark, heavily cratered regions that preserve an ancient history and brighter grooved regions shaped by tectonic activity. The moon is large enough to have a differentiated interior with a metallic core, rocky mantle, and ice-rich outer layers.

Ganymede also has a feature unique among known moons: its own intrinsic magnetic field. That field creates miniature auroral belts inside Jupiter’s much larger magnetosphere. Ganymede is often confused with Callisto, another large Jovian moon, but Callisto is smaller and more heavily cratered. Ganymede’s size, internal structure, and magnetic environment make it a major target for studying potentially habitable icy worlds.