Dione
Moon· orbits Saturn
Dione is a dense moon of Saturn whose trailing hemisphere is streaked with bright ice cliffs (chasmata) cutting across older cratered terrain.
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Key facts
Mass
1.10 × 10²¹ kg
0.0149 Moon masses
Radius
561 km
32% of our Moon's radius
Surface gravity
0.232 m/s²
2% of Earth's
Day length
2.7 days
Orbit around Saturn
2.74 Earth days
Science
Physical
- Mass
- 1.10 × 10²¹ kg · 0.0149 Moon masses
- Radius
- 561 km · 32% of our Moon's radius
- Density
- 1,478 kg/m³ · 1.5× water
- Surface gravity
- 0.232 m/s² · 2% of Earth's
- Escape velocity
- 510 m/s · 5% of Earth's
Orbit around Saturn
- Distance from Saturn
- 4,110,627 km
- Orbital period
- 2.7 days
- Eccentricity
- 0.002
- Inclination
- 0.00 °
Rotation
- Rotation period
- 2.7 days
- Tidal locking
- Tidally locked to its parent
Temperature
- Mean
- 87 K (-186 °C)
Composition
- Bulk composition
- A water-ice crust over a silicate-rock interior; possibly a small subsurface ocean.
Radiation & temperature
- Insolation
- 0.0112 S⊕ · 1% of the sunlight Earth receives
- Bond albedo
- 0.65 · reflects 65% of incoming sunlight
- Equilibrium temperature
- 70 K (-204 °C)
- Measured mean temperature
- 87 K (-186 °C)
- Greenhouse warming
- +17 K
Discovery & history
- Discovered
- March 21, 1684
- By
- Giovanni Domenico Cassini
- Method
- Visual discovery (telescopic)
- Name
- Dione, a Titaness of Greek myth.
Cassini found Dione on the same night as Tethys in 1684. Its trailing hemisphere is laced with bright icy cliffs — fractures hundreds of metres high that Voyager could see only as wispy streaks until Cassini resolved them.
Images
Images from open archives · credit shown per image