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Encyclopedia > Saturn > Satellites > Dione
DIONE : SATELLITE IV OF SATURN :
| Characteristics | Values |
|---|---|
| Semi-major axis in km | 377 654 |
| Revolution period | 2.737 days |
| Rotation period | 2.737 days |
| Orbital velocity | 11 km/s |
| Inclination on the equator of Saturn | 0.01° |
| Eccentricity of the orbit | 0.0022 |
| Equatorial diameter (Earth=1) | 0.08 |
| Equatorial diameter | 1120 km |
| Visual magnitude at the opposition | 10.4 |
| Flattening | 0 |
| Mass (Saturn=1) | 1.85/1000 000 |
| Density (Water=1) | 1.4 |
| Escape velocity | 436 m/s |
| Reflectivity (geometric albedo) | 0.9 |
| The highest peak | ? |
| Deepest pit | 5000m |
| Surface temperature | -187°C |
| Atmosphere | no |
| Composition | ices majority silicates |
Dione (Saturn IV) was discovered by Herschel in 1789. Space probes have revealed traces of ice on the surface of the satellite, also riddled with craters like its neighbors and a face "in the direction of travel" (the leading side) very different from the other.
As Tethys, Dione is not alone in its orbit, but is accompanied by the satellites Helene (in advance of 60 °) and Polydeuces (late of 60 °) on their common orbit. These are satellites of "Trojan" type.