Prometheus (moon)

Prometheus
	Prometheus image from Cassini (December 26, 2009)
Discovery
Discovered by	Stewart A. Collins; D. Carlson; Voyager 1
Discovery date	October, 1980
Designations
Designation	Saturn XVI
Pronunciation	/prəˈmiːθiːəs/
Named after	Προμηθεύς Promētheys
Adjectives	Promethean, -ian /prəˈmiːθiːən/
Orbital characteristics
	Epoch 31 December 2003 (JD 2453005.5)
Semi-major axis	139380±10 km
Eccentricity	0.0022
Orbital period	0.612990038 d
Inclination	0.008°±0.004° to Saturn's equator
Satellite of	Saturn
Group	Inner shepherd moon of the F Ring
Physical characteristics
Dimensions	137.0 × 81.0 × 56.2 km; (± 1.0 × 2.8 × 0.8 km)
Mean diameter	85.6±1.4 km
Volume	327740±1710 km3
Mass	(1.59720±0.00072)×1017 kg
Mean density	0.4873±0.0026 g/cm3
surface gravity	0.0007–0.0056 m/s2
escape velocity	0.018 km/s at longest axis; to 0.028 km/s at poles
Rotation period	synchronous
Axial tilt	zero
Albedo	0.6
Physics	≈ 74 K

Short description: Moon of Saturn

Prometheus /prəˈmiːθiːəs/ is an inner satellite of Saturn. It was discovered in 1980 (on October 24) from photos taken by the Voyager 1 probe, and was provisionally designated S/1980 S 27.^[6]

In late 1985 it was officially named after Prometheus, a Titan in Greek mythology.^[7] It is also designated Saturn XVI.^[8]

Prometheus is extremely elongated, measuring approximately 137 km × 81 km × 56 km (85 mi × 50 mi × 35 mi). It has several ridges and valleys and a number of impact craters of about 20 km (12 mi) 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.^[9]^[10]

Images from the Cassini probe show that the Promethean gravitational field creates kinks and knots in the F Ring as it 'steals' material from it. The orbit of Prometheus appears to be chaotic, due to a series of four 121:118 mean-motion resonances with Pandora.^[11] The most appreciable changes in their orbits occur approximately every 6.2 years,^[3] 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.^[3]

Selected images

Prometheus pulling material from the F Ring
Prometheus tugging kinks into the F Ring
Voyager 2 (August 25, 1981) image
Cassini image (with moon's Saturn-facing end at lower right) reveals a surface covered with a blanket of fine material.
Image from Jan. 27, 2010. Saturnshine illuminates the moon's night side.
Brightened version of same image
Prometheus flyby
(December 6, 2015)

Animations

Prometheus collides with the F ring, pulls a streamer, and leaves behind a dark channel. 12 seconds 107 kbit/s
Movie of Prometheus and the F Ring looped once. 5 seconds 48 kbit/s

Notes

↑ Calculated from the standard gravitational parameter GM = (1.06602±0.00048)×10⁻² km³·s^–2 given by Lainey et al. (2023), divided by the gravitational constant G = 6.6743×10⁻² km³·kg^–1·s^–2.^[5]

References

Citations

↑ "Prometheus". Prometheus. Oxford University Press. http://www.lexico.com/definition/Prometheus.
↑ "Promethean". Promethean. Oxford University Press. http://www.lexico.com/definition/Promethean.
↑ ^3.0 ^3.1 ^3.2 Spitale Jacobson et al. 2006.
↑ ^4.0 ^4.1 ^4.2 Thomas & Helfenstein 2020.
↑ ^5.0 ^5.1 ^5.2 Lainey et al. 2023.
↑ IAUC 3532.
↑ IAUC 4157.
↑ USGS: Planet and Satellite Names and Discoverers.
↑ "On the masses and motions of mini-moons: Pandora's not a "shepherd," but Prometheus still is". Planetary Society. 2014-07-05. http://www.planetary.org/blogs/emily-lakdawalla/2014/07010001-ringmoons-shepherds.html.
↑ Cuzzi, J. N.; Whizin, A. D.; Hogan, R. C.; Dobrovolskis, A. R.; Dones, L.; Showalter, M. R.; Colwell, J. E.; Scargle, J. D. (April 2014). "Saturn's F Ring core: Calm in the midst of chaos". Icarus 232: 157–175. doi:10.1016/j.icarus.2013.12.027. ISSN 0019-1035. Bibcode: 2014Icar..232..157C.
↑ Renner et al. 2005.

Sources

Marsden, Brian G. (October 31, 1980). "Satellites of Saturn" (discovery). IAU Circular 3532. http://www.cbat.eps.harvard.edu/iauc/03500/03532.html. Retrieved 2011-12-29.
Marsden, Brian G. (January 3, 1986). "Satellites of Saturn and Pluto" (naming the moon). IAU Circular 4157. http://www.cbat.eps.harvard.edu/iauc/04100/04157.html. Retrieved 2011-12-29.
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. doi:10.1016/j.icarus.2004.09.005. Bibcode: 2005Icar..174..230R.
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. doi:10.1086/505206. Bibcode: 2006AJ....132..692S.
Thomas, P. C. (July 2010). "Sizes, shapes, and derived properties of the saturnian satellites after the Cassini nominal mission". Icarus 208 (1): 395–401. doi:10.1016/j.icarus.2010.01.025. Bibcode: 2010Icar..208..395T. http://www.ciclops.org/media/sp/2011/6794_16344_0.pdf. Retrieved 2015-09-04.
USGS/IAU (July 21, 2006). "Planet and Satellite Names and Discoverers". Gazetteer of Planetary Nomenclature. USGS Astrogeology. http://planetarynames.wr.usgs.gov/Page/Planets#SaturnianSystem.
Thomas, P. C.; Helfenstein, P. (July 2020). "The small inner satellites of Saturn: Shapes, structures and some implications". Icarus 344: 20. doi:10.1016/j.icarus.2019.06.016. 113355. Bibcode: 2020Icar..34413355T.
Lainey, V.; Rambaux, N.; Cooper, N.; Dahoumane, R.; Zhang, Q. (February 2023). "Characterising the interior of five inner Saturnian moons using Cassini ISS data". Astronomy & Astrophysics 670: 6. doi:10.1051/0004-6361/202244757. L25. Bibcode: 2023A&A...670L..25L.

External links

"Cassini–Huygens: Multimedia-Videos / Soft Collision". NASA. http://saturn.jpl.nasa.gov/multimedia/videos/video-details.cfm?videoID=163. "Prometheus slowly collides with the diffuse inner edge of Saturn's F ring ... pulls a streamer of material from the ring and leaves behind a dark channel."
Prometheus Profile at NASA's Solar System Exploration site
The Planetary Society: Prometheus
3-D anaglyph view of Prometheus

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[6] Calculated from the standard gravitational parameter GM = (1.06602±0.00048)×10⁻² km³·s^–2 given by Lainey et al. (2023), divided by the gravitational constant G = 6.6743×10⁻² km³·kg^–1·s^–2.^[5]

[1] "Prometheus". Prometheus. Oxford University Press. http://www.lexico.com/definition/Prometheus.

[2] "Promethean". Promethean. Oxford University Press. http://www.lexico.com/definition/Promethean.

[FOOTNOTESpitale_Jacobson_et_al.2006-3] 3.0 ^3.1 ^3.2 Spitale Jacobson et al. 2006.

[FOOTNOTEThomas_&_Helfenstein2020-4] 4.0 ^4.1 ^4.2 Thomas & Helfenstein 2020.

[FOOTNOTELainey_et_al.2023-5] 5.0 ^5.1 ^5.2 Lainey et al. 2023.

[FOOTNOTEIAUC_3532-7] IAUC 3532.

[FOOTNOTEIAUC_4157-8] IAUC 4157.

[FOOTNOTEUSGS:_Planet_and_Satellite_Names_and_Discoverers-9] USGS: Planet and Satellite Names and Discoverers.

[LakdawallaE2014-10] "On the masses and motions of mini-moons: Pandora's not a "shepherd," but Prometheus still is". Planetary Society. 2014-07-05. http://www.planetary.org/blogs/emily-lakdawalla/2014/07010001-ringmoons-shepherds.html.

[Cuzzi2014-11] Cuzzi, J. N.; Whizin, A. D.; Hogan, R. C.; Dobrovolskis, A. R.; Dones, L.; Showalter, M. R.; Colwell, J. E.; Scargle, J. D. (April 2014). "Saturn's F Ring core: Calm in the midst of chaos". Icarus 232: 157–175. doi:10.1016/j.icarus.2013.12.027. ISSN 0019-1035. Bibcode: 2014Icar..232..157C.

[FOOTNOTERenner_et_al._2005-12] Renner et al. 2005.

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v t e Moons of Saturn
Listed in approximately increasing distance from Saturn.
Ring shepherds	S/2009 S 1 Ring moonlets Pan Daphnis Atlas Prometheus Pandora
Co-orbitals	Epimetheus Janus
G Ring	Aegaeon
Alkyonides	Methone Anthe Pallene
Inner large (with trojans)	Mimas Enceladus Tethys Telesto Calypso Dione Helene Polydeuces
Outer large	Rhea Titan Hyperion Iapetus
Inuit group	Kiviuq Ijiraq Paaliaq S/2004 S 29 S/2004 S 31 Siarnaq Tarqeq
Norse group	Phoebe Skathi S/2004 S 37 S/2007 S 2 Skoll S/2004 S 13(?) Greip Hyrrokkin Jarnsaxa Mundilfari S/2006 S 1 S/2004 S 17(?) Bergelmir Narvi S/2004 S 20 Suttungr Hati S/2004 S 12(?) S/2004 S 27 Farbauti Thrymr S/2004 S 30 Aegir S/2007 S 3(?) Bestla S/2004 S 7(?) S/2004 S 22(?) S/2004 S 23(?) S/2004 S 25(?) S/2004 S 32(?) S/2006 S 3 S/2004 S 38(?) Fenrir S/2004 S 28(?) Surtur Kari S/2004 S 35(?) Ymir S/2004 S 21(?) Loge S/2004 S 36(?) S/2004 S 39(?) S/2004 S 33(?) S/2004 S 34(?) Fornjot S/2004 S 26(?)
Gallic group	Albiorix Bebhionn Erriapus Tarvos
Prograde outer satellites	S/2004 S 24
Rings of Saturn Cassini–Huygens Themis Chiron S/2004 S 6 S/2004 S 4 S/2004 S 3 In fiction

v t e Saturn
Outline of Saturn
Geography	Dragon Storm Great White Spot Hexagon Magnetosphere Rings
Moons	S/2009 S 1 Ring moonlets Pan Daphnis Atlas Prometheus S/2004 S 6 S/2004 S 4 S/2004 S 3 Pandora Epimetheus Janus Aegaeon Mimas Methone Anthe Pallene Enceladus Tethys Telesto Calypso Dione Helene Polydeuces Rhea Titan Hyperion Iapetus Kiviuq Ijiraq Phoebe Paaliaq Skathi S/2004 S 37 Albiorix S/2007 S 2 S/2004 S 29 Bebhionn Erriapus Skoll S/2004 S 31 Siarnaq Tarqeq S/2004 S 13 Greip Hyrrokkin Jarnsaxa Tarvos Mundilfari S/2006 S 1 S/2004 S 17 Bergelmir Narvi S/2004 S 20 Suttungr Hati S/2004 S 12 S/2004 S 27 Farbauti Thrymr S/2004 S 30 Aegir S/2007 S 3 Bestla S/2004 S 7 S/2004 S 22 S/2004 S 23 S/2004 S 25 S/2004 S 32 S/2006 S 3 S/2004 S 38 Fenrir S/2004 S 28 Surtur Kari S/2004 S 35 Ymir S/2004 S 21 S/2004 S 24 Loge S/2004 S 36 S/2004 S 39 S/2004 S 33 S/2004 S 34 Fornjot S/2004 S 26
Astronomy	Delta Octantis Saturn-crossing minor planets
Exploration	Cassini–Huygens (Huygens) timeline retirement Pioneer 11 Voyager program Voyager 1 Voyager 2
Related	Fiction Moons The Day the Earth Smiled In Saturn's Rings (2018 documentary)