Prometheus (moon) explained
| Prometheus |
| Pronounced: | [1] |
| Adjective: | Promethean, -ian [2] |
| Named After: | Προμηθεύς Promētheys |
| Mpc Name: | Saturn XVI |
| Discoverer: | Stewart A. Collins
D. Carlson
Voyager 1 |
| Discovered: | October, 1980 |
| Epoch: | 31 December 2003 (JD) |
| Inclination: | to Saturn's equator |
| Satellite Of: | Saturn |
| Group: | Inner shepherd moon of the F Ring |
| Dimensions: | km
(± km) |
| Escape Velocity: | km/s at longest axis
to km/s at poles |
| Rotation: | synchronous |
| Axial Tilt: | zero |
| Albedo: | 0.6 |
| Single Temperature: | ≈ 74 K |
Prometheus is an inner satellite of Saturn. It was discovered on 24 October 1980 from images taken by the Voyager 1 probe, and was provisionally designated .
In late 1985 it was officially named after Prometheus, a Titan in Greek mythology. It is also designated .
Prometheus is extremely elongated, measuring approximately NaNkm (-2,147,483,648miles). It has several ridges and valleys and a number of impact craters of about 20km (10miles) diameter are visible, but it is less cratered than nearby Pandora, Epimetheus, and Janus. From its very low density and relatively high albedo, it is likely that Prometheus is a very porous icy body. There is much uncertainty in these values, however, and so this remains to be confirmed.
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.[3] [4]
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.
References
Sources
- Marsden . Brian G. . Satellites of Saturn . October 31, 1980 . discovery . IAU Circular . 3532 . 2011-12-29 . .
- Marsden . Brian G. . Satellites of Saturn and Pluto . January 3, 1986 . naming the moon . IAU Circular . 4157 . 2011-12-29 . .
- 10.1016/j.icarus.2004.09.005. Renner. Stéfan F.. Sicardy. Bruno. French. Richard G.. March 2005. Prometheus and Pandora: Masses and orbital positions during the Cassini tour. Icarus. 174. 1. 230–240. 2005Icar..174..230R. .
- 10.1086/505206. Spitale. J. N.. Jacobson. R. A.. Porco. C. C.. Owen. W. M. Jr. . 2006. The orbits of Saturn's small satellites derived from combined historic and Cassini imaging observations. The Astronomical Journal. 132. 2. 692–710. 2006AJ....132..692S. . free.
- 10.1016/j.icarus.2010.01.025. Thomas. P. C.. July 2010. Sizes, shapes, and derived properties of the saturnian satellites after the Cassini nominal mission. Icarus. 208. 1. 395–401. 2010Icar..208..395T. 2015-09-04. 2018-12-23. https://web.archive.org/web/20181223003125/http://www.ciclops.org/media/sp/2011/6794_16344_0.pdf. dead.
- Web site: . Planet and Satellite Names and Discoverers . July 21, 2006 . USGS Astrogeology . Gazetteer of Planetary Nomenclature . 2011-12-29 . .
- . P. C. . Thomas . P. . Helfenstein . The small inner satellites of Saturn: Shapes, structures and some implications . Icarus . July 2020 . 344 . 113355 . 20 . 10.1016/j.icarus.2019.06.016 . 2020Icar..34413355T. 197474587 .
- . V. . Lainey . N. . Rambaux . N. . Cooper . R. . Dahoumane . Q. . Zhang . Characterising the interior of five inner Saturnian moons using Cassini ISS data . Astronomy & Astrophysics . February 2023 . 670 . L25 . 6 . free . 10.1051/0004-6361/202244757 . 2023A&A...670L..25L.
External links
Notes and References
- Encyclopedia: Prometheus . https://web.archive.org/web/20200320063552/https://www.lexico.com/definition/prometheus . dead . March 20, 2020 . Lexico UK English Dictionary . Oxford University Press.
- Encyclopedia: Promethean . https://web.archive.org/web/20200320063559/https://www.lexico.com/definition/promethean . dead . March 20, 2020 . Lexico UK English Dictionary UK English Dictionary . Oxford University Press.
- Web site: Lakdawalla . E. . Emily Lakdawalla . On the masses and motions of mini-moons: Pandora's not a "shepherd," but Prometheus still is . . 2014-07-05 . 2015-04-17 .
- Cuzzi. J. N.. Whizin. A. D.. Hogan. R. C.. Dobrovolskis. A. R.. Dones. L. . Showalter. M. R.. Colwell. J. E.. Scargle. J. D.. Saturn's F Ring core: Calm in the midst of chaos. Icarus. 232. April 2014. 157–175. 0019-1035. 10.1016/j.icarus.2013.12.027. 2014Icar..232..157C .
