Moons · Moon of Jupiter

Ganymede

778 million km from the Sun · Light crosses it in 0.018 seconds

Across

5,268 km

Vs Earth

0.41× Earth

Mass

2.48% of Earth

Open Ganymede in Cosmic Scale

About

Ganymede is the largest moon in the Solar System — bigger than Mercury — and the only one with a magnetic field of its own, generated by a molten iron core. A salty ocean lies deep beneath its ice, holding more water than Earth's oceans.

The largest moon in the Solar System — bigger than Mercury.

At a glance

Orbits	Jupiter, every 7.2 days
Diameter	5,268 km
Ocean	Under ~150 km of ice
Discovered	1610, Galileo

Did you know

1. Its magnetic field carves out a small magnetosphere inside Jupiter's giant one, and drives auroras.
2. Europe's JUICE spacecraft, launched in 2023, will settle into orbit around it in 2034 — the first orbit of another planet's moon.
3. Dark ancient terrain and bright grooved terrain divide its surface almost in half.

Real photo

• Ganymede close up, from Juno's 2021 flyby — NASA/JPL-Caltech/SwRI/MSSS · source