Prometheus (moon)
Shepherd moon of Saturn's F Ring.
Prometheus is an inner satellite of Saturn, discovered on 24 October 1980 from images taken by the Voyager 1 probe. It is notable as a shepherd satellite for the inner edge of Saturn's narrow F Ring, and its gravitational influence creates kinks and knots in the ring.
Quick Facts
- Pronounced
- p · r · ə · ˈ · m · iː · θ · iː · ə · s
- Adjective
- Promethean, -ian p · r · ə · ˈ · m · iː · θ · iː · ə · n
- Named After
- Προμηθεύς Promētheys
- Mpc Name
- Saturn XVI
- Discoverer
- Stewart A. Collins / D. Carlson / Voyager 1
- Discovered
- 24 October 1980
- Eccentricity
- 0.00223
- Satellite Of
- Saturn
Facts from the source article.
Lore & Background
Prometheus was discovered on 24 October 1980 from images taken by the Voyager 1 probe, and was provisionally designated S/1980 S 27. In late 1985 it was officially named after Prometheus, a Titan in Greek mythology. It is also designated Saturn XVI. The moon is extremely elongated, measuring approximately 137 km × 81 km × 56 km. Its surface is heavily cratered, with several ridges and valleys and a number of impact craters of about 20 km diameter visible. From its very low density and relatively high albedo, it is likely a very porous icy body. The surface can be distinguished into two types of terrain, both equally cratered and separated by long scarps, one of which could be indicative of an exposed core section that would make up roughly two-thirds of the total volume. Its elongated shape could be a result of the low-speed merging of several similar-sized bodies.
Reader's Guide
Prometheus is a shepherd satellite for the inner edge of Saturn's narrow F Ring. While Pandora has traditionally been viewed as an outer shepherd, recent studies indicate that only Prometheus contributes to the confinement of the ring. Images from the Cassini probe show that Prometheus's gravitational influence creates kinks and knots in the F Ring as it shepherds material from it. The orbit of Prometheus appears to be chaotic, due to a series of four 121:118 mean-motion resonances with Pandora. The most appreciable changes in their orbits occur approximately every 6.2 years, when the periapsis of Pandora lines up with the apoapsis of Prometheus, as they approach to within approximately 1400 km. Prometheus is itself a significant perturber of Atlas, with which it is in a 53:54 mean-longitude resonance. It also participates in a 17:15 mean-motion resonance with Epimetheus, but only while it is on the outer orbit relative to Janus. Due to their gravitational interactions with the rings, Prometheus and Pandora are expected to crash into each other or Mimas in the next 20 million years.
More in Moons of Saturn 1-24
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