Ananke (moon)

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Discovered byS. B. Nicholson
Discovery dateSeptember 28, 1951
Orbital characteristics
Periapsis12,567,000 km
Apoapsis29,063,500 km
Mean orbit radius
21,280,000 km[1]
610.45 d (1.680 a)[1]
2.367 km/s
Inclination148.89° (to the ecliptic)
149.9° (to Jupiter's equator)[1]
Satellite ofJupiter
Physical characteristics
Mean radius
14 km[2]
~2500 km²
Volume~11,500 km³
Mass3.0×1016 kg
Mean density
2.6 g/cm³ (assumed)
0.010 m/s2 (0.001 g)
~0.017 km/s
Albedo0.04 (assumed)[2]
Temperature~124 K

Ananke is a retrograde non-spherical moon of Jupiter. It was found by Seth Barnes Nicholson at Mount Wilson Observatory in 1951[3] and is named after the mythological Ananke, the mother of Adrastea by Jupiter. The adjectival form of the name is Anankean.

Ananke did not get its present name[4] until 1975;[5] before then, it was simply known as Jupiter XII. It was sometimes called "Adrastea"[6] between 1955 and 1975. Note that Adrastea is now the name of another moon of Jupiter.

Ananke gives its name to the Ananke group, retrograde non-spherical moons which orbit Jupiter between 19,300,000 and 22,700,000 km, at inclinations of about 150°.[2]

Orbit[change | change source]

Retrograde irregular satellites of Jupiter.

Ananke orbits Jupiter on a high eccentricity and high inclination retrograde orbit. Eight non-spherical moons found since 2000 follow similar orbits.[2] The orbital elements are as of January 2000.[1] They are changing a lot due to Solar and planetary perturbations. The diagram illustrates Ananke's orbit in relation to other retrograde non-spherical moons of Jupiter. The eccentricity of selected orbits is represented by the yellow segments (extending from the pericentre to the apocentre). The farthest spherical moon Callisto is located for reference.

Given these orbital elements and the physical characteristics known so far, Ananke is thought to be the biggest remnant[7] of an original break-up forming the Ananke group.[8][9]

Physical characteristics[change | change source]

In the visible spectrum, Ananke appears grey to light-red.[9]

The infrared spectrum is similar to P-type asteroids but with a possible indication of water.[10]

References[change | change source]

  1. 1.0 1.1 1.2 1.3 1.4 Jacobson, R. A. (2000). "The Orbits of Outer Jovian Satellites". Astronomical Journal. 120 (5): 2679–2686. doi:10.1086/316817. S2CID 120372170.
  2. 2.0 2.1 2.2 2.3 Sheppard, S. S., Jewitt, D. C., Porco, C.; Jupiter's Outer Satellites and Trojans, in Jupiter: The Planet, Satellites and Magnetosphere, edited by Fran Bagenal, Timothy E. Dowling, William B. McKinnon, Cambridge Planetary Science, Vol. 1, Cambridge, UK: Cambridge University Press, ISBN 0-521-81808-7, 2004, pp. 263-280
  3. 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. doi:10.1086/126402. S2CID 121080345.
  4. 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. doi:10.1086/125010. S2CID 122937855.
  5. Marsden, B. G. (7 October 1974). "Satellites of Jupiter". IAUC Circular. 2846.
  6. Payne-Gaposchkin, Cecilia; Katherine Haramundanis (1970). Introduction to Astronomy. Englewood Cliffs, N.J.: Prentice-Hall. ISBN 0-134-78107-4.
  7. Sheppard, S.S.; Jewitt, D.C. (2003). "An abundant population of small irregular satellites around Jupiter" (PDF). Nature. 423 (6937): 261–263. doi:10.1038/nature01584. PMID 12748634. S2CID 4424447.
  8. Nesvorný, D.; Beaugé, C. and Dones, L. (2004). "Collisional Origin of Families of Irregular Satellites". The Astronomical Journal. 127 (3): 1768–1783. doi:10.1086/382099. S2CID 27293848.{{cite journal}}: CS1 maint: multiple names: authors list (link)[permanent dead link]
  9. 9.0 9.1 Grav, Tommy; Holman, M.J.; Gladman, B. J.; Aksnes, K. (2003). "Photometric survey of the irregular satellites -_". Icarus. 166: 33-45. arXiv:astro-ph/0301016. doi:10.1016/j.icarus.2003.07.005. S2CID 7793999.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  10. Grav, Tommy; Holman, Matthew J. (2004). "Near-Infrared Photometry of the Irregular Satellites of Jupiter and Saturn". The Astrophysical Journal. 605 (2): L141–L144. arXiv:astro-ph/0312571. doi:10.1086/420881. S2CID 15665146.
  1. Ephemeris IAU-MPC NSES

Other websites[change | change source]