Discovered byVoyager 2
Discovered in1980
Orbital characteristics
Semimajor axis139,350 km
Orbital period14h 42m 42s
Is a satellite ofSaturn
Physical characteristics
Mean radius50.1 km
Surface area km2
Mass3.3×1017 kg
Mean density0.63 g/cm3
Surface gravity0.0087m/s2
Rotation periodunknown
Axial tilt

Prometheus is a moon of Saturn, named after Prometheus from Greek mythology. It was discovered in 1980 from Voyager photos. Prometheus acts as a shepherd satellite for the inner edge of Saturn's F ring.

This small moon is extremely elongated about 148 by 100 by 68 kilometers. It has several ridges and valleys and a number of craters about 20 kilometers are visible, but it is less cratered than nearby Pandora, Epimetheus and Janus. From its very low density and relatively high albedo, it seems likely that Prometheus is a very porous icy body. There is a lot of uncertainty in these values, however, and so this remains to be confirmed.