Ganymede

The giant moon

Vital statistics

• Mean radius: 2,634 kilometres
• Mass: 1.48 × 10²³ kilograms
• Surface gravity: 1.43 metres per second squared
• Sidereal rotation: 7.2 days
• Orbital period: 7.16 days
• Mean temperature: -163 °C
• Axial tilt: 0.2 degrees

Field notes

• Ganymede is the largest moon in the solar system — bigger than the planet Mercury.
• It is the only moon known to generate its own magnetic field, complete with its own auroras.
• Like Europa, it likely hides a vast saltwater ocean — possibly layered between sheets of exotic high-pressure ice.

Data: NASA Planetary Fact Sheets. Explore the full interactive 3D map at the home page — every orbit is computed from real Keplerian elements.