Prometheus (moon)

Interactions with F Ring and other moons

Prometheus is a shepherd satellite for the inner edge of Saturn's narrow F Ring. Pandora orbits just outside the F Ring, and has traditionally been viewed as an outer shepherd of the ring; however, recent studies indicate that only Prometheus contributes to the confinement of the ring.{{cite web | access-date = 2015-04-17 }}

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.

Prometheus also participates in a 17:15 mean-motion resonance with Epimetheus, but only while it is on the outer orbit relative to Janus. No such configuration with Janus exists.

Gallery

Selected images

| File:Prometheus's effect on the F Ring.jpg|Prometheus pulling material from the F Ring | File:Prometheus tugging on F Ring PIA09909.jpg|Prometheus tugging kinks into the F Ring | File:Prometheus - Voyager 2.jpg|Voyager 2 (August 25, 1981) image | File:Prometheus 12-26-09a.jpg|Cassini image (with moon's Saturn-facing end at lower right) reveals a surface covered with a blanket of fine material. | File:PIA12593 Prometheus.jpg|Image from Jan. 27, 2010. Saturnshine illuminates the moon's night side. | File:PIA12593 Prometheus2.jpg|Brightened version of same image | File:PIA17207-SaturnMoon-Prometheus-20151206.jpg|Prometheus flyby (December 6, 2015)

Animations

| File:Prometheus collides with F ring PIA08397 ff025.ogv|Prometheus collides with the F ring, pulls a streamer, and leaves behind a dark channel. 12 seconds 107 kbit/s | File:Prometheus F ring from PIA08262 fr25 twice.ogv|Movie of Prometheus and the F Ring looped once. 5 seconds 48 kbit/s

References

Notes

Citations

Sources

• {{cite journal | access-date = 2011-12-29
• {{cite journal | access-date = 2011-12-29
• {{cite web | access-date = 2011-12-29
• {{cite journal
• {{cite journal |doi-access = free

References

1. "Prometheus". [[Oxford University Press]].
2. "Promethean". [[Oxford University Press]].
3. (April 2014). "Saturn's F Ring core: Calm in the midst of chaos". Icarus.
4. Cooper, N. J.. (2014-12-24). "SATURNʼS INNER SATELLITES: ORBITS, MASSES, AND THE CHAOTIC MOTION OF ATLAS FROM NEW CASSINI IMAGING OBSERVATIONS". The Astronomical Journal.