Prometheus (moon) - Definition and Overview

Prometheus

Discovery
Discovered by	Voyager 1
Discovered in	1980
Orbital characteristics
Semimajor axis	139,350 km
Eccentricity	0.0024
Orbital period	14 h 42 min 42 s
Inclination	0 °
Is a satellite of	Saturn
Physical characteristics
Mean diameter	100.2 km
Surface area	km2
Mass	3.3×1017 kg
Mean density	0.63 g/cm3
Surface gravity	0.0087m/s2
Rotation period	unknown
Axial tilt	0°
Albedo	0.6
Atmosphere	none

Prometheus ("pro MEE thee us") is a moon of Saturn. It was discovered in 1980 from Voyager photos, and was designated 1980 S 27. In 1985 it was officially named after Prometheus, a Titan in Greek mythology. There is also an asteroid called 1809 Prometheus.

This small moon is extremely elongated, measuring about 148 by 100 by 68 km. It has several ridges and valleys and a number of craters of about 20 km diameter 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.

Prometheus acts as a shepherd satellite for the inner edge of Saturn's F Ring. Recent images from the Cassini probe show that Prometheus's gravitational attraction creates kinks and knots in the F Ring as the moon 'steals' material from it.