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Aegaeon (moon)

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Aegaeon (2008 S1).jpg
Three images of the bright arc of the G-Ring with Aegaeon (within box) embedded.
Discovered by Carolyn Porco
Discovery date March 3, 2009 (2009-03-03)
Cassini Imaging Science Team
Orbital characteristics
Epoch JD 2454467.00075444 TDB
167493.665±0.004 km [1]
Eccentricity 0.00042277±0.00000004 [1]
0.80812 d [2]
Inclination 0.0007°±0.6° [1]
(linear drift) 445.475±0.007 °/day
Physical characteristics
Mean radius
250 metres (0.16 mi)[1][2]
Mean density
0.5 kg/m3[1]

Aegaeon (/ˈən/ ee-JEE-ən; or as Greek Αιγαίων), also Saturn LIII (provisional designation S/2008 S 1), is a natural satellite of Saturn. It is thought to be similarly smooth as Methone.[3]

Discovery and naming[edit]

Images of Aegaeon were taken by Cassini on August 15, 2008, and its discovery was announced on March 3, 2009 by Carolyn Porco of the Cassini Imaging Science Team using the provisional designation S/2008 S 1.[2]

Aegaeon was named after Ægæon, one of the hekatonkheires, on 5 May 2009.[4]


Aegaeon orbits within the bright segment of Saturn's G Ring, and is probably a major source of the ring.[5] 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,[1] 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. Assuming it has the same albedo as Pallene, it is estimated to be half a kilometer in diameter. 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.[2]


  1. ^ a b c d e f 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" (PDF). Icarus 207 (1): 433–447. doi:10.1016/j.icarus.2009.10.024. Retrieved 3 April 2015. 
  2. ^ a b c d IAU Circular No. 9023
  3. ^ Battersby, S. (2013-05-17). "Saturn's egg moon Methone is made of fluff". New Scientist web site. New Scientist. Retrieved 2013-05-21. 
  4. ^ Jennifer Blue, Saturnian Satellite Named Aegaeon, USGS Astrogeology Hot Topics, 5 May 2009
  5. ^ Petite Moon, CICLOPS, 29 May 2009