Ananke (moon)

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Categories: Jupiter's moons | Irregular satellites

**Ananke**
Discovery
Discovered by	S. B. Nicholson
Discovery date	September 28, 1951
Orbital characteristics
Periapsis	12,567,000 km
Apoapsis	29,063,500 km
Mean orbit radius	21,280,000 km^[2]
Eccentricity	0.24^[2]
Orbital period	610.45 d (1.680 a)^[2]
Average orbital speed	2.367 km/s
Inclination	148.89° (to the ecliptic) 149.9° (to Jupiter's equator)^[2]
Satellite of	Jupiter
Physical characteristics
Mean radius	14 km^[3]
Surface area	~2500 km²
Volume	~11,500 km³
Mass	3.0×10¹⁶ kg
Mean density	2.6 g/cm³ (assumed)
Equatorial surface gravity	0.010 m/s² (0.001 g)
Escape velocity	~0.017 km/s
Albedo	0.04 (assumed)^[3]
Temperature	~124 K

Ananke (ə-nang'-kee, IPA: /əˈnæŋki/; Greek Ανάγκη) is a retrograde irregular satellite of Jupiter. It was discovered by Seth Barnes Nicholson at Mount Wilson Observatory in 1951^[4] and is named after the mythological Ananke, the mother of Adrastea by Jupiter. The adjectival form of the name is Anankean.

Ananke did not receive its present name^[5] until 1975;^[6] before then, it was simply known as Jupiter XII. It was sometimes called "Adrastea"^[7] between 1955 and 1975. Note that Adrastea is now the name of another satellite of Jupiter.

Ananke gives its name to the Ananke group, retrograde irregular moons which orbit Jupiter between 19.3 and 22.7 Gm, at inclinations of roughly 150°.^[3]

1 Orbit
2 Physical characteristics
3 See also
4 References
5 External links

Orbit

Image:TheIrregulars JUPITER retro.svg

Retrograde irregular satellites of Jupiter.

Ananke orbits Jupiter on a high eccentricity and high inclination retrograde orbit. Eight irregular satellites discovered since 2000 follow similar orbits.^[3]The orbital elements are as of January 2000.^[2] They are continuously changing due to Solar and planetary perturbations. The diagram illustrates Ananke's orbit in relation to other retrograde irregular satellites of Jupiter. The eccentricity of selected orbits is represented by the yellow segments (extending from the pericentre to the apocentre). The outermost regular satellite Callisto is located for reference.

Given these orbital elements and the physical characteristics known so far, Ananke is thought to be the largest remnant^[8] of an original break-up forming the Ananke group.^[9]^[10]

Physical characteristics

In the visible spectrum, Ananke appears neutral to light-red (colour indices B-V=0.90 V-R=0.38).^[10]

The infrared spectrum is similar to P-type asteroids but with a possible indication of water.^[11]

References

^ [1]
^ ^a ^b ^c ^d ^e Jacobson, R. A. (2000). "The Orbits of Outer Jovian Satellites". Astronomical Journal 120: pp. 2679-2686. doi:10.1086/316817.
^ ^a ^b ^c ^d
^ Nicholson, S. B. (1951). "An unidentified object near Jupiter, probably a new satellite". Publications of the Astronomical Society of the Pacific 63 (375): 297–299.
^ Nicholson, S.B. (April 1939). "S. B. Nicholson declines to name the satellites of Jupiter he has discovered". Publications of the Astronomical Society of the Pacific 51 (300): 85–94.
^ Marsden, B. G. (7 October 1974). "Satellites of Jupiter". IAUC Circular 2846.
^ Payne-Gaposchkin, Cecilia; Katherine Haramundanis (1970). Introduction to Astronomy. Englewood Cliffs, N.J.: Prentice-Hall. ISBN 0-134-78107-4.
^ Sheppard, S.S.; Jewitt, D.C. (2003). "An abundant population of small irregular satellites around Jupiter". Nature 423: 261-263.
^ Nesvorný, D.; Beaugé, C.;Dones, L. (2004). "Collisional Origin of Families of Irregular Satellites". The Astronomical Journal 127: 1768–1783.
^ ^a ^b Grav, Tommy (2003). "Photometric survey of the irregular satellites". Icarus 166: 33-45. doi:10.1016/j.icarus.2003.07.005.
^ Grav, Tommy (2004). "Near-Infrared Photometry of the Irregular Satellites of Jupiter and Saturn". The Astrophysical Journal 605: L141–L144.

Ephemeris IAU-MPC NSES

External links

v • d • e

Moons of Jupiter

Listed in increasing distance from Jupiter. Temporary names in italics.

Inner moons

Metis · Adrastea · Amalthea · Thebe

Galilean moons

Io · Europa · Ganymede · Callisto

Themisto

Himalia group

Leda · Himalia · Lysithea · Elara · S/2000 J 11

Carpo · S/2003 J 12

Ananke group

core	Ananke · Praxidike · Harpalyke · Iocaste · Euanthe · Thyone
peripheral	Euporie · S/2003 J 3 · S/2003 J 18 · Thelxinoe · Helike · Orthosie · S/2003 J 16 · Hermippe · Mneme · S/2003 J 15

Carme group

S/2003 J 17 · S/2003 J 10 · Pasithee · Chaldene · Arche · Isonoe · Erinome · Kale · Aitne · Taygete · S/2003 J 9 · Carme · S/2003 J 5 · S/2003 J 19 · Kalyke · Eukelade · Kallichore

Pasiphaë group