View source for Prometheus (moon)

{{Short description|Moon of Saturn}}
{{For|the asteroid|1809 Prometheus}}
{{Infobox planet
| name = Prometheus
| image = Prometheus 12-26-09b.jpg
| image_scale = 
| caption = Prometheus image from ''[[Cassini–Huygens|Cassini]]'' (December 26, 2009)
| pronounced = {{IPAc-en|p|r|ə|ˈ|m|iː|θ|iː<!--[sic] - long /iː/ with -ευς-->|ə|s}}<ref>{{Cite encyclopedia |url=http://www.lexico.com/definition/Prometheus |archive-url=https://web.archive.org/web/20200320063552/https://www.lexico.com/definition/prometheus |url-status=dead |archive-date=March 20, 2020 |title=Prometheus |dictionary=[[Lexico]] UK English Dictionary |publisher=[[Oxford University Press]]}}</ref>
| adjective = Promethean, -ian {{IPAc-en|p|r|ə|ˈ|m|iː|θ|iː|ə|n}}<ref>{{Cite encyclopedia |url=http://www.lexico.com/definition/Promethean |archive-url=https://web.archive.org/web/20200320063559/https://www.lexico.com/definition/promethean |url-status=dead |archive-date=March 20, 2020 |title=Promethean |dictionary=[[Lexico]] UK English Dictionary UK English Dictionary |publisher=[[Oxford University Press]]}}</ref>
| named_after = [[Prometheus|Προμηθεύς]] ''Promētheys''
| mpc_name = Saturn XVI
| discoverer = [[Stewart A. Collins]]<br/>D. Carlson<br/>[[Voyager 1]]
| discovered = 24 October 1980
| orbit_ref =  {{sfn|Spitale Jacobson et al.|2006}}
| epoch = 31 December 2003 ([[Julian day|JD]] {{val|2453005.5}})
| semimajor = {{val|139380|10|u=km}}
| eccentricity = {{val|0.0022}}
| period = {{val|0.612990038|u=d}}
| inclination = {{val|0.008|0.004|u=°}} to Saturn's equator
| satellite_of = [[Saturn]]
| group = Inner [[shepherd moon]] of the [[F Ring]]
| dimensions = {{val|137.0|x|81.0|x|56.2}}&nbsp;km<br/>(±&nbsp;{{val|1.0|x|2.8|x|0.8}}&nbsp;km){{sfn|Thomas & Helfenstein|2020}}{{rp|page=2}}
| mean_diameter = {{val|85.6|1.4|u=km}}{{sfn|Thomas & Helfenstein|2020}}{{rp|page=2}}
| volume = {{val|327740|1710|u=km3}}{{sfn|Lainey et al.|2023}}{{rp|page=4}}
| mass = {{val|1.59720|0.00072|e=17|u=kg}}{{efn|Calculated from the standard gravitational parameter ''GM'' {{=}} {{val|1.06602|0.00048|e=-2|u=km<sup>3</sup>·s<sup>–2</sup>}} given by Lainey et al. (2023), divided by the [[gravitational constant]] ''G'' {{=}} {{val|6.6743|e=-2|u=km<sup>3</sup>·kg<sup>–1</sup>·s<sup>–2</sup>}}.{{sfn|Lainey et al.|2023}}}}
| density = {{val|0.4873|0.0026|u=g/cm3}}{{sfn|Lainey et al.|2023}}{{rp|page=4}}
| surface_grav = {{val|0.0007|-|0.0056|u=m/s2}}{{sfn|Thomas & Helfenstein|2020}}{{rp|page=3}}
| escape_velocity = {{V2|1.59720e-4|68.5|3}}&nbsp;km/s at longest axis<br/>to {{V2|1.59720e-4|28.1|3}}&nbsp;km/s at poles<!-- V2 template uses mass in terms of e+21 kg, radius in terms of km, and number of decimal places -->
| rotation = [[synchronous rotation|synchronous]]
| axial_tilt = zero
| albedo = 0.6
| single_temperature = ≈ 74 K
}}

'''Prometheus''' {{IPAc-en|p|r|ə|ˈ|m|iː|θ|iː|ə|s}} 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 '''{{nowrap|S/1980 S 27}}'''.{{sfn|IAUC 3532}}

In late 1985 it was officially named after [[Prometheus]], a [[Titan (mythology)|Titan]] in [[Greek mythology]].{{sfn|IAUC 4157}} It is also designated '''{{nowrap|Saturn XVI}}'''.{{sfn|USGS: Planet and Satellite Names and Discoverers}}

Prometheus is extremely elongated, measuring approximately {{convert|137 x 81 x 56|km|mi|abbr=on}}. It has several ridges and valleys and a number of [[impact crater]]s of about {{convert|20|km|mi|abbr=on}} diameter are visible, but it is less cratered than nearby [[Pandora (moon)|Pandora]], [[Epimetheus (moon)|Epimetheus]], and [[Janus (moon)|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 moon|shepherd satellite]] for the inner edge of Saturn's narrow [[F Ring]]. [[Pandora (moon)|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.<ref name = "LakdawallaE2014">{{cite web
 | last = Lakdawalla | first = E. | author-link = Emily Lakdawalla
 | title = On the masses and motions of mini-moons: Pandora's not a "shepherd", but Prometheus still is
 | publisher = [[Planetary Society]] | date = 2014-07-05
 | url = http://www.planetary.org/blogs/emily-lakdawalla/2014/07010001-ringmoons-shepherds.html
 | access-date = 2015-04-17 }}</ref><ref name="Cuzzi2014">{{cite journal|last1=Cuzzi|first1=J. N.|last2=Whizin|first2=A. D.|last3=Hogan|first3=R. C.|last4=Dobrovolskis|first4=A. R.|last5=Dones|first5=L. |last6=Showalter|first6=M. R.|last7=Colwell|first7=J. E.|last8=Scargle|first8=J. D.|title=Saturn's F Ring core: Calm in the midst of chaos|journal=Icarus|volume=232|date=April 2014|pages=157–175|issn=0019-1035|doi=10.1016/j.icarus.2013.12.027|bibcode = 2014Icar..232..157C }}</ref>

Images from the [[Cassini–Huygens|''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 [[orbital resonance#Types of resonances|mean-motion resonances]] with [[Pandora (moon)|Pandora]].{{sfn|Renner et al. 2005}} The most appreciable changes in their orbits occur approximately every 6.2 years,{{sfn|Spitale Jacobson et al.|2006}} when the [[apsis|periapsis]] of Pandora lines up with the apoapsis of Prometheus, as they approach to within approximately 1400&nbsp;km. Prometheus is itself a significant perturber of [[Atlas (moon)|Atlas]], with which it is in a 53:54 mean-longitude resonance.{{sfn|Spitale Jacobson et al.|2006}}

{{clear}}

== Selected images ==
{{gallery
| title = 
| width = 200
| 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. [[Planetshine|Saturnshine]] illuminates the moon's night side.
| File:PIA12593 Prometheus2.jpg|Brightened version of same image
| File:PIA17207-SaturnMoon-Prometheus-20151206.jpg|Prometheus flyby<br>(December 6, 2015)
}}

== Animations ==
{{gallery
| title = 
| width = 400
| 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&nbsp;kbit/s
| File:Prometheus F ring from PIA08262 fr25 twice.ogv|Movie of Prometheus and the F Ring looped once. 5 seconds 48&nbsp;kbit/s
}}

== Notes ==
{{notelist}}

== References ==

=== Citations ===

{{reflist}}

=== Sources ===

* {{cite journal
  | last = Marsden
  | first = Brian G.
  | title = Satellites of Saturn
  | date = October 31, 1980
  | format = discovery
  | journal = IAU Circular
  | issue = 3532
  | url = http://www.cbat.eps.harvard.edu/iauc/03500/03532.html
  | access-date = 2011-12-29
  | ref = {{sfnRef|IAUC 3532}}
  }}
* {{cite journal
  | last = Marsden
  | first = Brian G.
  | title = Satellites of Saturn and Pluto
  | date = January 3, 1986
  | format = naming the moon
  | journal = IAU Circular
  | issue = 4157
  | url = http://www.cbat.eps.harvard.edu/iauc/04100/04157.html
  | access-date = 2011-12-29
  | ref = {{sfnRef|IAUC 4157}}
  }}
* {{cite journal| doi = 10.1016/j.icarus.2004.09.005| last1 = Renner| first1 = Stéfan F.| last2 = Sicardy| first2 = Bruno| last3 = French| first3 = Richard G.| date = March 2005| title = Prometheus and Pandora: Masses and orbital positions during the Cassini tour| journal = [[Icarus (journal)|Icarus]]| volume = 174| issue = 1| pages = 230–240| bibcode=2005Icar..174..230R| ref = {{sfnRef|Renner et al. 2005}}}}
* {{cite journal| doi = 10.1086/505206| last1 = Spitale| first1 = J. N.| last2 = Jacobson| first2 = R. A.| last3 = Porco| first3 = C. C.| last4 = Owen| first4 = W. M. Jr. | year = 2006| title = The orbits of Saturn's small satellites derived from combined historic and ''Cassini'' imaging observations| journal = The Astronomical Journal| volume = 132| issue = 2| pages = 692–710| bibcode = 2006AJ....132..692S| ref = {{sfnRef|Spitale Jacobson et al.|2006}}| doi-access = free}}
* {{cite journal| doi = 10.1016/j.icarus.2010.01.025| last1 = Thomas| first1 = P. C.| date = July 2010| title = Sizes, shapes, and derived properties of the saturnian satellites after the Cassini nominal mission| journal = Icarus| volume = 208| issue = 1| pages = 395–401| url = http://www.ciclops.org/media/sp/2011/6794_16344_0.pdf| bibcode = 2010Icar..208..395T| access-date = 2015-09-04| archive-date = 2018-12-23| archive-url = https://web.archive.org/web/20181223003125/http://www.ciclops.org/media/sp/2011/6794_16344_0.pdf| url-status = dead}}
* {{cite web
  | author = [[USGS]]/[[IAU]]
  | title = Planet and Satellite Names and Discoverers
  | date = July 21, 2006
  | publisher = USGS Astrogeology
  | work = Gazetteer of Planetary Nomenclature
  | url = https://planetarynames.wr.usgs.gov/Page/Planets#SaturnianSystem
  | access-date = 2011-12-29
  | ref = {{sfnRef|USGS: Planet and Satellite Names and Discoverers}}
  }}
* {{cite journal
  |ref = {{sfnRef|Thomas & Helfenstein|2020}}
  |first1 = P. C. |last1 = Thomas
  |first2 = P. |last2 = Helfenstein
  |title      = The small inner satellites of Saturn: Shapes, structures and some implications
  |journal    = Icarus
  |date       = July 2020
  |volume     = 344
  |id         = 113355
  |pages      = 20
  |doi        = 10.1016/j.icarus.2019.06.016
  |bibcode    = 2020Icar..34413355T|s2cid = 197474587 }}
* {{cite journal
  |ref = {{sfnRef|Lainey et al.|2023}}
  |first1 = V. |last1 = Lainey
  |first2 = N. |last2 = Rambaux
  |first3 = N. |last3 = Cooper
  |first4 = R. |last4 = Dahoumane
  |first5 = Q. |last5 = Zhang
  |title      = Characterising the interior of five inner Saturnian moons using Cassini ISS data
  |journal    = Astronomy & Astrophysics
  |date       = February 2023
  |volume     = 670
  |id         = L25
  |pages      = 6
  |doi-access = free
  |doi        = 10.1051/0004-6361/202244757
  |bibcode    = 2023A&A...670L..25L}}

== External links ==
{{Spoken Wikipedia|Prometheus (moon).ogg|date=2010-01-10}}
{{commons category-inline|bullet=none}}
* {{cite web |title=Cassini–Huygens: Multimedia-Videos / Soft Collision |publisher=[[NASA]] |url=http://saturn.jpl.nasa.gov/multimedia/videos/video-details.cfm?videoID=163 |archive-url=https://web.archive.org/web/20071029205038/http://saturn.jpl.nasa.gov/multimedia/videos/video-details.cfm?videoID=163 |archive-date=29 October 2007 |quote=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.}}
* [https://web.archive.org/web/20070609144848/http://solarsystem.nasa.gov/planets/profile.cfm?Object=Sat_Prometheus Prometheus Profile] at [http://solarsystem.nasa.gov NASA's Solar System Exploration site]
* [https://web.archive.org/web/20060830121943/http://www.planetary.org/explore/topics/saturn/prometheus.html The Planetary Society: Prometheus]
* [http://ciclops.org/view/6133/Prometheus_Popping_in_3-D 3-D] [[Anaglyph image|anaglyph]] view of Prometheus

{{Moons of Saturn}}
{{Saturn}}

{{DEFAULTSORT:Prometheus (Moon)}}
[[Category:Moons of Saturn]]
[[Category:Astronomical objects discovered in 1980]]
[[Category:Articles containing video clips]]
[[Category:Prometheus]]
[[Category:Discoveries by Stewart A. Collins]]
[[Category:Moons with a prograde orbit]]