Galilean moon · moon of Jupiter
Ganymede
The largest moon in the Solar System – bigger than Mercury – and the only moon known to generate its own magnetic field.
- Distance from Earth today
- 817.9 million km5.468 AU · light: 45 min 28 s
- Distance from the Sun today
- 795.2 million km5.315 AU
- As of
- 3 November 2026position from NASA/JPL orbital elements
Where it is today
Top view of the plane of Earth’s orbit, compressed distance scale. Open on the big map with the time slider →
Facts
- Diameter
- 5,262 km
- Mass
- 148,148 × 10¹⁸ kg
- Density
- 1,942 kg/m³
- Mean distance from the planet
- 1,070,400 km
- Orbital period
- 7.16 days
- Orbital eccentricity
- 0.0010
- Orbital inclination
- 0.2°
Source of the figures: JPL SSD – Planetary Satellites (public domain).
Discovery: 1610 – Galileo Galilei
Description
Ganymede is the largest moon in the Solar System, wider even than the planet Mercury, though much less massive. Its surface combines dark, ancient, heavily cratered regions with lighter terrain carved by grooves and ridges. Galileo spacecraft data showed that it is the only moon with its own internally generated magnetic field, and there is strong evidence for a salty ocean buried deep beneath its icy crust. Voyager 1 and 2, Galileo and Juno have all observed it, and ESA's JUICE mission, launched in 2023, is set to become the first spacecraft to orbit a moon other than our own when it settles around Ganymede.