December 17, 2004
Phoebe is about 220 kilometers (140 miles) in diameter. Earth-based observations indicate Phoebe is almost certainly a captured asteroid, and did not form from the original Saturn nebula as Saturn's other satellites did. Unlike the larger Saturnian satellites, Phoebe does not always show the same face to Saturn. While its orbital period is 550 days, Phoebe¿s rotation period (length of day) is nine to ten hours. Phoebe orbits Saturn close to the ecliptic (the plane in which Earth and most other planets orbit the Sun), rather than in Saturn's equatorial plane as the other Saturn satellites do. And Phoebe's orbit is retrograde -- in the direction opposite to that of the other satellites.
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