Astronomy:Aegaeon (moon)
![]() Aegaeon's crescent imaged by the Cassini spacecraft from a distance of 15238.2 km in 2010 | |
Discovery | |
---|---|
Discovered by | Carolyn Porco |
Discovery date | March 3, 2009 |
Cassini Imaging Science Team | |
Designations | |
Designation | Saturn LIII |
Pronunciation | /iːˈdʒiːɒn/[1] |
Named after | Αιγαίων Aigaiōn |
Adjectives | Aegaeonian /iːdʒiːˈoʊniən/[2] |
Orbital characteristics | |
Epoch JD 2454467.00075444 TDB | |
Eccentricity | 0.00042277±0.00000004 [3] |
Orbital period | 0.80812 d [4] |
Inclination | 0.0007°±0.6° [3] |
Satellite of | Saturn |
Group | Source of the G Ring |
Physical characteristics | |
Dimensions | 1.40 × 0.50 × 0.40 km (± 0.10 × 0.12 × 0.16 km)[5](p2) |
Mean diameter | 0.66±0.12 km[5](p2) |
Volume | 0.15 km3[lower-alpha 1] |
Mass | (7.82±3.00)×1010 kg[5](p3) |
Mean density | 0.539±0.140 g/cm3[5](p3) |
0.009–0.013 mm/s2[5](p3) (0.9–1.3 micro-g) | |
0.001 km/s at longest axis to 0.002 km/s at poles | |
Rotation period | assumed synchronous |
Albedo | < 0.15 |
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 it was discovered 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 acquire any images from a planned close flyby.
Notes
References
- ↑ Noah Webster (1884) A Practical Dictionary of the English Language
- ↑ Maravilla & Leal-Herrera (2014) 'The Saturnian G-Ring: A Short Note about its Formation', Revista Mexicana de Astronomía y Astrofísica, p. 342, 346, 347
- ↑ 3.0 3.1 3.2 Cite error: Invalid
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tag; no text was provided for refs namedIcarus
- ↑ 4.0 4.1 4.2 "IAU Circular No. 9023". http://ciclops.org/view/5518/S2008_S_1?js=1.
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 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.
- ↑ Battersby, S. (2013-05-17). "Saturn's egg moon Methone is made of fluff". www.newscientist.com. New Scientist. https://www.newscientist.com/article/dn23560-astrophile-saturns-egg-moon-methone-is-made-of-fluff.html.
- ↑ Jennifer Blue, Saturnian Satellite Named Aegaeon, USGS Astrogeology Hot Topics, 5 May 2009
- ↑ Petite Moon , 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". Icarus 226 (1): 999–1019. doi:10.1016/j.icarus.2013.07.022. Bibcode: 2013Icar..226..999T. http://webpages.uidaho.edu/mhedman/papers_published/Thomas_littlesats_Icarus_2013.pdf. Retrieved 2 December 2015.
- ↑ 10.0 10.1 10.2 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)". European Planetary Space Conference. 6. http://yly-mac.gps.caltech.edu/A_DPS/dps%202011%20/a_dps%202011%20program%20+%20abstracts/pdf/EPSC-DPS2011-531-2.pdf. Retrieved 2 December 2015.
- ↑ Planetary Society Cassini Timeline
![]() | Original source: https://en.wikipedia.org/wiki/Aegaeon (moon).
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