Aegaeon (moon)
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.
Aegaeon was named after one of the hekatonkheires on 5 May 2009.
Orbit
Aegaeon orbits within the bright segment of Saturn's G Ring, and is probably a major source of the ring. 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, 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.
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. Measurements of its mass show that Aegaeon has a very low density, likely due to a highly porous and icy interior structure. Aegaeon has the lowest albedo, below 0.15, of any Saturnian moon inward of Titan. 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.
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. An encounter on 27 January 2010 at a distance 13,306 km allowed Cassini to acquire its highest resolution images of Aegaeon. 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)
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. Bibcode:2014RMxAA..50..341M. ISSN 0185-1101.
- ^ 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.
- ^ "IAU Circular No. 9023". Archived from the original on 2019-05-01. Retrieved 2009-03-04.
- ^ 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.
- ^ 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
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