Astronomy:Aegaeon (moon)

Aegaeon
	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
Detection method	Cassini Imaging Science Team
Designations
Designation	Saturn LIII
Pronunciation	/iːˈdʒiːɒn/
Named after	Αιγαίων Aigaiōn
Adjectives	Aegaeonian /iːdʒiːˈoʊniən/
Orbital characteristics
	Epoch JD 2454467.00075444 TDB
Eccentricity	0.00042277±0.00000004
Orbital period	0.80812 d
Inclination	0.0007°±0.6°
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)
Mean diameter	0.66±0.12 km
Volume	0.15 km3
Mass	(7.82±3.00)×1010 kg
Mean density	0.539±0.140 g/cm3
surface gravity	0.009–0.013 mm/s2; (0.9–1.3 micro-g)
escape velocity	0.001 km/s at longest axis; to 0.002 km/s at poles
Rotation period	assumed synchronous
Albedo	< 0.15

Short description: Moon of Saturn

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

2008 Cassini images of the bright G Ring arc with Aegaeon embedded within it. These images were taken over the course of ten minutes.

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

↑ Calculated from Aegaeon's volume-equivalent sphere radius of 0.33±0.06 km given by Thomas et al. (2020)^[5]^(p2)

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 <ref> tag; no text was provided for refs named Icarus
↑ ^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

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Original source: https://en.wikipedia.org/wiki/Aegaeon (moon). Read more

[6] Calculated from Aegaeon's volume-equivalent sphere radius of 0.33±0.06 km given by Thomas et al. (2020)^[5]^(p2)

[1] Noah Webster (1884) A Practical Dictionary of the English Language

[2] Maravilla & Leal-Herrera (2014) 'The Saturnian G-Ring: A Short Note about its Formation', Revista Mexicana de Astronomía y Astrofísica, p. 342, 346, 347

[Icarus-3] 3.0 ^3.1 ^3.2 Cite error: Invalid <ref> tag; no text was provided for refs named Icarus

[IAUCircular-4] 4.0 ^4.1 ^4.2 "IAU Circular No. 9023". http://ciclops.org/view/5518/S2008_S_1?js=1.

[Thomas2020-5] 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.

[Smooth-7] 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.

[8] Jennifer Blue, Saturnian Satellite Named Aegaeon, USGS Astrogeology Hot Topics, 5 May 2009

[9] Petite Moon , CICLOPS, 29 May 2009

[Icarus2-10] 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.

[DPS-11] 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.

[PSCassini-12] Planetary Society Cassini Timeline

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v t e Moons of Saturn
Listed in approximately increasing distance from Saturn.
Ring shepherds	S/2009 S 1 Ring moonlets Pan Daphnis Atlas Prometheus Pandora
Co-orbitals	Epimetheus Janus
G Ring	Aegaeon
Alkyonides	Methone Anthe Pallene
Inner large (with trojans)	Mimas Enceladus Tethys Telesto Calypso Dione Helene Polydeuces
Outer large	Rhea Titan Hyperion Iapetus
Inuit group	Kiviuq Ijiraq Paaliaq S/2004 S 29 S/2004 S 31 Siarnaq Tarqeq
Norse group	Phoebe Skathi S/2004 S 37 S/2007 S 2 Skoll S/2004 S 13(?) Greip Hyrrokkin Jarnsaxa Mundilfari S/2006 S 1 S/2004 S 17(?) Bergelmir Narvi S/2004 S 20 Suttungr Hati S/2004 S 12(?) S/2004 S 27 Farbauti Thrymr S/2004 S 30 Aegir S/2007 S 3(?) Bestla S/2004 S 7(?) S/2004 S 22(?) S/2004 S 23(?) S/2004 S 25(?) S/2004 S 32(?) S/2006 S 3 S/2004 S 38(?) Fenrir S/2004 S 28(?) Surtur Kari S/2004 S 35(?) Ymir S/2004 S 21(?) Loge S/2004 S 36(?) S/2004 S 39(?) S/2004 S 33(?) S/2004 S 34(?) Fornjot S/2004 S 26(?)
Gallic group	Albiorix Bebhionn Erriapus Tarvos
Prograde outer satellites	S/2004 S 24
Rings of Saturn Cassini–Huygens Themis Chiron S/2004 S 6 S/2004 S 4 S/2004 S 3 In fiction

v t e Saturn
Outline of Saturn
Geography	Dragon Storm Great White Spot Hexagon Magnetosphere Rings
Moons	S/2009 S 1 Ring moonlets Pan Daphnis Atlas Prometheus S/2004 S 6 S/2004 S 4 S/2004 S 3 Pandora Epimetheus Janus Aegaeon Mimas Methone Anthe Pallene Enceladus Tethys Telesto Calypso Dione Helene Polydeuces Rhea Titan Hyperion Iapetus Kiviuq Ijiraq Phoebe Paaliaq Skathi S/2004 S 37 Albiorix S/2007 S 2 S/2004 S 29 Bebhionn Erriapus Skoll S/2004 S 31 Siarnaq Tarqeq S/2004 S 13 Greip Hyrrokkin Jarnsaxa Tarvos Mundilfari S/2006 S 1 S/2004 S 17 Bergelmir Narvi S/2004 S 20 Suttungr Hati S/2004 S 12 S/2004 S 27 Farbauti Thrymr S/2004 S 30 Aegir S/2007 S 3 Bestla S/2004 S 7 S/2004 S 22 S/2004 S 23 S/2004 S 25 S/2004 S 32 S/2006 S 3 S/2004 S 38 Fenrir S/2004 S 28 Surtur Kari S/2004 S 35 Ymir S/2004 S 21 S/2004 S 24 Loge S/2004 S 36 S/2004 S 39 S/2004 S 33 S/2004 S 34 Fornjot S/2004 S 26
Astronomy	Delta Octantis Saturn-crossing minor planets
Exploration	Cassini–Huygens (Huygens) timeline retirement Pioneer 11 Voyager program Voyager 1 Voyager 2
Related	Fiction Moons The Day the Earth Smiled In Saturn's Rings (2018 documentary)

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Discovery and naming

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Physical characteristics

Exploration

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Discovery
Aegaeon's crescent imaged by the Cassini spacecraft from a distance of 15238.2 km in 2010
Discovered by	Carolyn Porco
Discovery date	March 3, 2009 (2009-03-03)
Detection method	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)
surface gravity	0.009–0.013 mm/s²^[5]^(p3) (0.9–1.3 micro-g)
escape velocity	0.001 km/s at longest axis to 0.002 km/s at poles
Rotation period	assumed synchronous
Albedo	< 0.15

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Astronomy:Aegaeon (moon)

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