Callisto
Moon· orbits Jupiter
Callisto is the outermost Galilean moon and among the most heavily cratered bodies known — an ancient, dark, only partly differentiated mix of rock and ice that may conceal a deep ocean.
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Key facts
Mass
1.08 × 10²³ kg
0.018 M⊕
Radius
2,410 km
1.39× wider than our Moon
Surface gravity
1.24 m/s²
13% of Earth's
Day length
16.7 days
Orbit around Jupiter
16.69 Earth days
Science
Physical
- Mass
- 1.08 × 10²³ kg · 0.018 M⊕
- Radius
- 2,410 km · 1.39× wider than our Moon
- Density
- 1,834 kg/m³ · 1.8× water
- Surface gravity
- 1.24 m/s² · 13% of Earth's
- Escape velocity
- 2.44 km/s · 22% of Earth's
Orbit around Jupiter
- Distance from Jupiter
- 3,088,658 km
- Orbital period
- 16.7 days
- Eccentricity
- 0.007
- Inclination
- 0.30 °
Rotation
- Rotation period
- 16.7 days
- Tidal locking
- Tidally locked to its parent
Temperature
- Mean
- 134 K (-139 °C)
Composition
- Bulk composition
- A nearly uniform mixture of rock and water ice, only partly differentiated, possibly over a deep salty ocean.
Radiation & temperature
- Insolation
- 0.0358 S⊕ · 4% of the sunlight Earth receives
- Bond albedo
- 0.12 · reflects 12% of incoming sunlight
- Equilibrium temperature
- 117 K (-156 °C)
- Measured mean temperature
- 134 K (-139 °C)
- Greenhouse warming
- +17 K
Discovery & history
- Discovered
- January 7, 1610
- By
- Galileo Galilei
- Method
- Visual discovery (telescopic)
- Name
- Callisto, a nymph and companion of Artemis loved by Zeus. Like her sibling Galilean moons, named by Simon Marius in 1614 at Kepler's suggestion; Galileo referred to them by number.
The outermost Galilean moon, found in 1610. Its ancient, heavily cratered surface is among the oldest in the Solar System.
Images
Images from open archives · credit shown per image