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Encyclopedia > Saturn > Outer satellites I


Credit : NASA
Phoebe as seen, left by Voyager and right by Cassini

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.

Origin of the name : click here.