Moon of Jupiter · Updated May 2026
Ganymede.
Ganymede is the largest moon in the solar system, with a 5,268 km diameter — bigger than the planet Mercury, though only 45% as massive. It is the only moon known to generate its own magnetic field, produced by a salty subsurface ocean and a partially molten iron core. Ganymede orbits Jupiter every 7.15 days.
View Jupiter system in 3D →Key facts
Ganymede has more water than all of Earth's oceans combined — most of it locked in an ocean roughly 100 km below the icy surface, sandwiched between layers of high-pressure ice.
About Ganymede
Ganymede's surface is a mix of ancient dark cratered terrain and lighter grooved terrain reshaped by tectonic activity billions of years ago. ESA's JUICE spacecraft, launched 2023, will enter Ganymede orbit in 2034 — the first orbital mission of any moon outside Earth's.
How to view Ganymede in 3D
Ganymede orbits Jupiter in real time inside the interactive viewer. Open the parent body to see the orbital geometry, or use the object browser to fly directly to the moon and observe its rotation, surface, and orbit.
Open the Jupiter system →Sources & methodology
Numbers cross-referenced with the sources below; updated May 2026.