Pandora is one of the inner, "shepherd" satellites embedded in Saturn's ring system. Along with Prometheus, which is in almost the same orbit, it traps dust particles ejected from the two moons by meteorite impacts, to form the F ring. The inner of the two moons gradually gains on the outer one (since smaller orbits have shorter orbital periods), and when it laps the outer one, their gravitational interaction causes small changes ("perturbations") in each others' orbits. As a result, Pandora and Prometheus' orbits are slightly "chaotic", varying irregularly around their average orbital elements. |
Pandora, as seen by Voyager 2 on August 25, 1981 (NASA, JPL, Voyager 2)
Pandora, as photographed by the Cassini spacecraft, in 2005
(Cassini Imaging Team, SSI, JPL, ESA, NASA, apod051123)
Data for Pandora
Discovered by S.Collins and others in 1980, from Voyager 1 photographs
Named after the first woman, the wife of Epimetheus
Orbital size 141,700 km (about 88,000 miles) (just outside F ring)
Orbital eccentricity 0%
Orbital inclination 0 degrees
Orbital period 15.0 hours
Diameter about 110 x 90 x 60 km (about 68 x 55 x 39 miles) (quite irregular)
Mass, density and surface gravity quite uncertain
Albedo (reflectivity) 90%
Outer of two shepherd moons (inner is Prometheus) which control F ring
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