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Encyclopedia > Saturn > Outer satellites I
Phoebe (Saturn IX) was discovered by Pickering in 1898. It was the farthest satellite from Saturn : amazingly, it rotates around Saturn in a retrograde mode contrarily to the main satellites. It is probably a body captured by the planet Saturn.
Since 2000, large new telescopes allowed to discover new small satellites similar to Phoebe.
| Characteristics | Values |
|---|---|
| semi-major axis | 12 893 240 km |
| mean size | 220 km |
| visual magnitude | 16,5 |
| period of revolution | 546 days and 14 hours |
| period of rotation | 9 hours and 17 minutes |
| orbital velocity | 2 km/s |
| inclination of the orbit on the equateur of Saturn |
174° (retrograde) |
| eccentricity of the orbit | 0.1756 |
| density (water=1) | 0.07 |
| escape velocity | 70 m/s |
| reflectivity (geometric albedo) | 0.06 |
Phoebe is especially dark. It is probably a class C asteroid (carbon) captured by Saturn.