Ananke () is a retrograde irregular moon of Jupiter. It was discovered by

Seth Barnes Nicholson Seth Barnes Nicholson (November 12, 1891 – July 2, 1963) was an American astronomer. He worked at the Lick observatory in California, and is known for discovering several moons of Jupiter in the 20th century. Nicholson was born in Springfield, ...

Mount Wilson Observatory The Mount Wilson Observatory (MWO) is an astronomical observatory in Los Angeles County, California, United States. The MWO is located on Mount Wilson, a peak in the San Gabriel Mountains near Pasadena, northeast of Los Angeles. The observat ...

in 1951 and is named after the Greek mythological

Ananke In ancient Greek religion, Ananke (; grc, Ἀνάγκη), from the common noun , "force, constraint, necessity") is the personification of inevitability, compulsion and necessity. She is customarily depicted as holding a spindle. One of the ...

, the personification of necessity, and the mother of the

Moirai In ancient Greek religion and mythology, the Moirai (, also spelled Moirae or Mœræ; grc, Μοῖραι, "lots, destinies, apportioners"), often known in English as the Fates ( la, Fata, Fata, -orum (n)=), were the personifications of fat ...

(Fates) by

Zeus Zeus or , , ; grc, Δῐός, ''Diós'', label= genitive Boeotian Aeolic and Laconian grc-dor, Δεύς, Deús ; grc, Δέος, ''Déos'', label= genitive el, Δίας, ''Días'' () is the sky and thunder god in ancient Greek relig ...

. The adjectival form of the name is ''Anankean''. Ananke did not receive its present name until 1975; before then, it was simply known as . It was sometimes called "Adrastea" between 1955 and 1975 ( Adrastea is now the name of another satellite of Jupiter). Ananke gives its name to the

Ananke group The Ananke group is a group of retrograde irregular satellites of Jupiter that follow similar orbits to Ananke and are thought to have a common origin. Their semi-major axes (distances from Jupiter) range between 19.3 and 22.7 Gm, their orbit ...

, retrograde irregular moons which orbit Jupiter between 19.3 and 22.7 Gm, at inclinations of roughly 150°. 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, , 2004, pp. 263-280

Orbit

Ananke orbits Jupiter on a high-eccentricity and high-inclination retrograde orbit. Fifteen irregular satellites orbiting Jupiter have been discovered since 2000 following similar orbits. The orbital elements are as of January 2000. 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 An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary (astronomy), primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two ...

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 of an original break-up, forming the

Physical characteristics

In the visible

spectrum A spectrum (plural ''spectra'' or ''spectrums'') is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word was first used scientifically in optics to describe the rainbow of colors ...

, Ananke appears neutral to light-red ( colour indices B-V=0.90 V-R=0.38). The

infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of Light, visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from ...

spectrum is similar to

P-type asteroid P-type asteroids are asteroids that have low albedo and a featureless reddish spectrum. It has been suggested that they have a composition of organic rich silicates, carbon and anhydrous silicates, possibly with water ice in their interior. P-ty ...

s but with a possible indication of water.

References

Sources * Ephemeri
IAU-MPC NSES

External links

Ananke Profile
b
NASA's Solar System Exploration
{{DEFAULTSORT:Ananke (Moon) Ananke group Moons of Jupiter Irregular satellites 19510928 Discoveries by Seth B. Nicholson Moons with a retrograde orbit

Orbit

Physical characteristics

See also

References

External links