Aegaeon (moon)
Aegaeon /iːˈdʒiːɒn/, or Saturn LIII (provisional designation S/2008 S 1), is a natural satellite of Saturn. It has an extremely elongated shape whose surface is thought to be similarly smooth as Methone.[6] It orbits between Janus and Mimas within Saturn's G Ring.
Discovery and naming
Images of Aegaeon were taken by Cassini on 15 August 2008, and its discovery was announced on 3 March 2009 by Carolyn Porco of the Cassini Imaging Science Team using the provisional designation S/2008 S 1.[4]
Aegaeon was named after one of the hekatonkheires on 5 May 2009.[7]
Orbit
Aegaeon orbits within the bright segment of Saturn's G Ring, and is probably a major source of the ring.[8] Debris knocked off Aegaeon forms a bright arc near the inner edge, which in turn spreads to form the rest of the ring. Aegaeon orbits in a 7:6 corotation eccentricity resonance with Mimas,[3] which causes an approximately 4-year oscillation of about 4 km in its semi-major axis, and a corresponding oscillation of a few degrees in its mean longitude. It orbits Saturn at an average distance of 167,500 km in 0.80812 days, at an inclination of 0.001° to Saturn's equator, with an eccentricity of 0.0002.[4]
Physical characteristics
Aegaeon is the smallest known moon of Saturn outside of the rings and has an extremely elongated shape, measuring 1.4 km × 0.5 km × 0.4 km (0.87 mi × 0.31 mi × 0.25 mi) in size.[9] Measurements of its mass show that Aegaeon has a very low density, likely due to a highly porous and icy interior structure.[5] Aegaeon has the lowest albedo, below 0.15, of any Saturnian moon inward of Titan.[10] This might be due to either darker meteoric material making up the dust in the G ring or due to Aegaeon having been disrupted, stripping away its ice-rich surface and leaving the rocky inner core behind.[10]
Exploration
The Cassini spacecraft has performed four flybys of Aegaeon closer than 20,000 km, though only one has occurred since its discovery in 2008. The closest of these pre-discovery encounters took place on 5 September 2005 at a distance of 8,517 km.[11] An encounter on 27 January 2010 at a distance 13,306 km allowed Cassini to acquire its highest resolution images of Aegaeon.[10] On 19 December 2015, Cassini was unable to capture any images from a planned close flyby.
Notes
- ^ Calculated from Aegaeon's volume-equivalent sphere radius of 0.33±0.06 km given by Thomas et al. (2020)[5]: 2
References
- ^ Noah Webster (1884) A Practical Dictionary of the English Language
- ^ Maravilla, D.; Leal-Herrera, J. L. (2014). "The Saturnian G-Ring: A Short Note about its Formation". Revista Mexicana de Astronomía y Astrofísica. 50 (2): 342, 346, 347. ISSN 0185-1101.
- ^ a b c d Hedman, M.M.; Cooper, N.J.; Murray, C.D.; Beurle, K.; Evans, M.W.; Tiscareno, M.S.; Burns, J.A. (May 2010). "Aegaeon (Saturn LIII), a G-ring object". Icarus. 207 (1): 433–447. arXiv:0911.0171. Bibcode:2010Icar..207..433H. doi:10.1016/j.icarus.2009.10.024. S2CID 118559643.
- ^ a b c "IAU Circular No. 9023". Archived from the original on 2019-05-01. Retrieved 2009-03-04.
- ^ a b c d e f g Thomas, P. C.; Helfenstein, P. (July 2020). "The small inner satellites of Saturn: Shapes, structures and some implications". Icarus. 344: 20. Bibcode:2020Icar..34413355T. doi:10.1016/j.icarus.2019.06.016. S2CID 197474587. 113355.
- ^ Battersby, S. (2013-05-17). "Saturn's egg moon Methone is made of fluff". www.newscientist.com. New Scientist. Retrieved 2013-05-21.
- ^ Jennifer Blue, Saturnian Satellite Named Aegaeon, USGS Astrogeology Hot Topics, 5 May 2009
- ^ Petite Moon Archived 2011-07-25 at the Wayback Machine, CICLOPS, 29 May 2009
- ^ Thomas, P.C.; Burns, J.A.; Hedman, M.; Helfenstein, P.; Morrison, S.; Tiscareno, M.S.; Veverka, J. (2013). "The inner small satellites of Saturn: A variety of worlds" (PDF). Icarus. 226 (1): 999–1019. Bibcode:2013Icar..226..999T. doi:10.1016/j.icarus.2013.07.022. Retrieved 2 December 2015.
- ^ a b c Hedman, M.M.; Burns, J.A.; Thomas, P.C.; Tiscareno, M.S.; Evans, M.W. (2011). Physical Properties of the small moon Aegaeon (Saturn LIII) (PDF). European Planetary Space Conference. Icarus. Vol. 6. Archived from the original (PDF) on 4 March 2016. Retrieved 2 December 2015.
- ^ Planetary Society Cassini Timeline
- v
- t
- e
- S/2009 S 1
- Aegaeon
- Pan
- Daphnis
- Prometheus
- Epimetheus
- Janus
- Atlas
- Pandora
- Methone
- Anthe
- Pallene
(with trojans)
Kiviuq subgroup |
|
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Paaliaq subgroup | |
Siarnaq subgroup |
- Albiorix
- Bebhionn
- S/2007 S 8
- Saturn LX
- Erriapus
- Tarvos
- S/2020 S 4
Phoebe subgroup |
|
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- Skathi
- S/2007 S 5
- S/2007 S 7
- S/2007 S 2
- S/2004 S 37
- S/2004 S 47
- S/2004 S 40
- S/2019 S 2
- S/2019 S 3
- S/2020 S 7
- Skoll
- S/2020 S 2
- S/2019 S 4
- S/2004 S 41
- S/2004 S 42
- Hyrrokkin
- Greip
- S/2004 S 13
- S/2007 S 6
- Mundilfari
- S/2006 S 1
- S/2004 S 43
- S/2006 S 10
- S/2019 S 5
- Gridr
- Bergelmir
- Jarnsaxa
- Narvi
- Suttungr
- S/2007 S 3
- S/2004 S 44
- S/2004 S 45
- Hati
- S/2004 S 17
- S/2006 S 11
- S/2004 S 12
- Eggther
- S/2006 S 13
- S/2007 S 9
- S/2019 S 7
- S/2019 S 8
- Farbauti
- Thrymr
- Bestla
- S/2019 S 9
- S/2004 S 46
- Angrboda
- S/2019 S 11
- Aegir
- Beli
- S/2019 S 10
- S/2019 S 12
- Gerd
- S/2019 S 13
- S/2006 S 14
- Gunnlod
- S/2019 S 15
- S/2020 S 6
- S/2004 S 7
- S/2006 S 3
- S/2005 S 5
- Skrymir
- S/2006 S 16
- S/2006 S 15
- S/2004 S 28
- S/2020 S 8
- Alvaldi
- Kari
- S/2004 S 48
- Geirrod
- Fenrir
- S/2004 S 50
- S/2006 S 17
- S/2004 S 49
- S/2019 S 17
- Surtur
- S/2006 S 18
- Loge
- Ymir
- S/2019 S 19
- S/2004 S 21
- S/2019 S 18
- S/2004 S 39
- S/2019 S 16
- S/2004 S 53
- S/2004 S 36
- Thiazzi
- S/2019 S 20
- S/2006 S 19
- Saturn LXIV
- Fornjot
- S/2004 S 51
- S/2020 S 10
- S/2020 S 9
- Saturn LVIII
- S/2019 S 21
- S/2004 S 52
irregular moons
- Rings of Saturn
- Cassini–Huygens
- Chiron
- Chrysalis
- Themis
- S/2004 S 3
- S/2004 S 4
- S/2004 S 6
- In fiction