# Ananke group

> Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Ananke_group
> Markdown URL: https://mediated.wiki/source/Ananke_group.md
> Source: https://en.wikipedia.org/wiki/Ananke_group
> Source revision: 1355670109
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

Group of retrograde irregular satellites of Jupiter

This diagram compares the [orbital elements](/source/Orbital_elements) and relative sizes of the known members of the Ananke group as of April 2026[\[update\]](https://en.wikipedia.org/w/index.php?title=Ananke_group&action=edit). The horizontal axis illustrates their average distance from Jupiter, the vertical axis their orbital inclination, and the circles their relative sizes.

107 irregular moons of Jupiter plotted by semi-major axis and inclination as of April 2026[\[update\]](https://en.wikipedia.org/w/index.php?title=Ananke_group&action=edit). The Ananke group is shown as a tight cluster of yellow-colored points on the left.

The **Ananke group** (or *family* or *cluster*) is a group of [retrograde](/source/Retrograde_motion) [irregular satellites](/source/Irregular_satellite) of [Jupiter](/source/Jupiter) that follow similar [orbits](/source/Orbit) to [Ananke](/source/Ananke_(moon)) and are thought to have a common origin.

Their [semi-major axes](/source/Semi-major_axis) (distances from Jupiter) range between 19.2 and 21.8 million km, their [orbital inclinations](/source/Orbital_inclination) between 144.3° and 155.5°, and their [orbital eccentricities](/source/Orbital_eccentricity) between 0.09 and 0.30.

The [International Astronomical Union](/source/International_Astronomical_Union) (IAU) reserves names ending in **-e** for all retrograde moons of Jupiter, including this group's members.

## Origin

The Ananke group is believed to have been formed when an [asteroid](/source/Asteroid) was captured by Jupiter and subsequently fragmented by a collision. This belief is founded on the fact that the [dispersion](/source/Dispersion_relation) of the [mean orbital parameters](/source/Proper_orbital_elements)[a] of the core members is very small and can be accounted for by a small velocity impulse (15 < δV < 80 m/s), compatible with a single collision and breakup.[1]

Based on the sizes of the satellites, the original asteroid may have been about 28 km in diameter. Since this value is near the approximate diameter of Ananke itself, it is likely the parent body was not heavily disrupted.[2]

Available photometric studies put this in doubt, however, and suggest that [secular resonance](/source/Secular_resonance) has mixed the Ananke and [Pasiphae groups](/source/Pasiphae_group): three of the moons of the former family ([Harpalyke](/source/Harpalyke_(moon)), [Praxidike](/source/Praxidike_(moon)) and [Iocaste](/source/Iocaste_(moon))) display similar grey colours (average [colour indices](/source/Color_index): B−V = 0.77 and V−R = 0.42) while Ananke itself is on the boundary between grey and light red.[3]

## Classification

The Ananke group is typically simply visually identified in orbital element space, differing in inclination from the [Carme group](/source/Carme_group) and having smaller semi-major axes than the Pasiphae group. However, some authors only consider the tight cluster immediately surrounding Ananke to be part of its group.[1][4][5] At other times, there is no distinction made between the Ananke and Pasiphae groups, and the two may be considered a single group.[3][6][7]

## List

The members of the Ananke group are (in order of date announcement):[8][4]

Name Diameter (km)[9] Semi-Major Axis (km) Period (days)[10][b] Ananke 28 21029500 –623.11 Iocaste 5 21062300 –624.55 Harpalyke 4 20887500 –616.78 Praxidike 7 20931100 –618.72 Thyone 4 20972700 –620.59 Hermippe 4 21103600 –626.38 Euanthe 3 20822900 –613.93 Orthosie 2 20897800 –617.23 Euporie 2 19261900 –546.18 S/2003 J 2 2 20992900 –621.47 Eupheme 2 20763400 –611.32 Helike 4 20911400 –617.86 S/2003 J 12 1 20959300 –619.96 S/2003 J 16 2 20877500 –622.88 S/2003 J 18 2 20332800 –592.33 Mneme 2 20815800 –613.61 Thelxinoe 2 20972300 –620.55 S/2010 J 2 1 20786900 –612.35 S/2016 J 1 1 20796700 –612.78 S/2017 J 3 2 20936500 –618.97 S/2017 J 7 2 20960400 –620.02 S/2017 J 9 3 21764200 –656.05 S/2021 J 1 1 20954700 –619.77 S/2021 J 2 1 20926600 –618.50 S/2021 J 3 2 20776600 –611.87 S/2022 J 3 1 21015100 –622.44 S/2017 J 10 2 21075800 –625.15 S/2010 J 6 2 21489800 –643.67 S/2021 J 8 1 20978900 –620.85

## Notes

1. **[^](#cite_ref-1)** [Osculating orbital parameters](/source/Osculating_orbit) of irregular satellites of Jupiter change widely in short intervals due to heavy [perturbation](/source/Perturbation_(astronomy)) by the Sun. For example, changes of as much as 1 million km in semi-major axis in 2 years, 0.5 in eccentricity in 12 years, and as much as 5° in inclination in 24 years have been reported. Mean orbital elements are the averages calculated by the numerical integration of current elements over a long period of time, used to determine the dynamical families.

1. **[^](#cite_ref-12)** Negative period is indicative of retrograde motion.

## References

1. ^ [***a***](#cite_ref-Nesvorny2003_2-0) [***b***](#cite_ref-Nesvorny2003_2-1) Nesvorný, David; Alvarellos, Jose L. A.; Dones, Luke; Levison, Harold F. (July 2003). ["Orbital and Collisional Evolution of the Irregular Satellites"](https://doi.org/10.1086%2F375461). *[The Astronomical Journal](/source/The_Astronomical_Journal)*. **126** (1): 398–429. [Bibcode](/source/Bibcode_(identifier)):[2003AJ....126..398N](https://ui.adsabs.harvard.edu/abs/2003AJ....126..398N). [doi](/source/Doi_(identifier)):[10.1086/375461](https://doi.org/10.1086%2F375461). [S2CID](/source/S2CID_(identifier)) [8502734](https://api.semanticscholar.org/CorpusID:8502734).

1. **[^](#cite_ref-3)** [Sheppard, Scott S.](/source/Scott_S._Sheppard); [Jewitt, David C.](/source/David_C._Jewitt) (5 May 2003). ["An abundant population of small irregular satellites around Jupiter"](https://web.archive.org/web/20060813235622/http://www.ifa.hawaii.edu/~jewitt/papers/JSATS/SJ2003.pdf) (PDF). *Nature*. **423** (6937): 261–263. [Bibcode](/source/Bibcode_(identifier)):[2003Natur.423..261S](https://ui.adsabs.harvard.edu/abs/2003Natur.423..261S). [doi](/source/Doi_(identifier)):[10.1038/nature01584](https://doi.org/10.1038%2Fnature01584). [PMID](/source/PMID_(identifier)) [12748634](https://pubmed.ncbi.nlm.nih.gov/12748634). [S2CID](/source/S2CID_(identifier)) [4424447](https://api.semanticscholar.org/CorpusID:4424447). Archived from [the original](http://www.ifa.hawaii.edu/~jewitt/papers/JSATS/SJ2003.pdf) (PDF) on 13 August 2006.

1. ^ [***a***](#cite_ref-Grav2003_4-0) [***b***](#cite_ref-Grav2003_4-1) [Grav, Tommy](/source/Tommy_Grav); [Holman, Matthew J.](/source/Matthew_J._Holman); [Gladman, Brett](/source/Brett_Gladman); [Aksnes, Kaare](/source/Kaare_Aksnes) (2 January 2003). "Photometric Survey of the Irregular Satellites". *[Icarus](/source/Icarus_(journal))*. **166** (1): 33–45. [arXiv](/source/ArXiv_(identifier)):[astro-ph/0301016](https://arxiv.org/abs/astro-ph/0301016). [Bibcode](/source/Bibcode_(identifier)):[2003Icar..166...33G](https://ui.adsabs.harvard.edu/abs/2003Icar..166...33G). [doi](/source/Doi_(identifier)):[10.1016/j.icarus.2003.07.005](https://doi.org/10.1016%2Fj.icarus.2003.07.005). [S2CID](/source/S2CID_(identifier)) [7793999](https://api.semanticscholar.org/CorpusID:7793999).

1. ^ [***a***](#cite_ref-Nesvorny2004_5-0) [***b***](#cite_ref-Nesvorny2004_5-1) Nesvorný, David; Beaugé, Cristian; Dones, Luke (2004). ["Collisional Origin of Families of Irregular Satellites"](https://doi.org/10.1086%2F382099). *[The Astronomical Journal](/source/The_Astronomical_Journal)*. **127** (3): 1768–1783. [Bibcode](/source/Bibcode_(identifier)):[2004AJ....127.1768N](https://ui.adsabs.harvard.edu/abs/2004AJ....127.1768N). [doi](/source/Doi_(identifier)):[10.1086/382099](https://doi.org/10.1086%2F382099). [S2CID](/source/S2CID_(identifier)) [27293848](https://api.semanticscholar.org/CorpusID:27293848) – via [IOP Publishing](/source/IOP_Publishing).

1. **[^](#cite_ref-Brozović&Jacobson2017_6-0)** Brozović, Marina; Jacobson, Robert A. (1 April 2017). ["The Orbits of Jupiter's Irregular Satellites"](https://doi.org/10.3847%2F1538-3881%2Faa5e4d). *The Astronomical Journal*. **153** (4): 147. [Bibcode](/source/Bibcode_(identifier)):[2017AJ....153..147B](https://ui.adsabs.harvard.edu/abs/2017AJ....153..147B). [doi](/source/Doi_(identifier)):[10.3847/1538-3881/aa5e4d](https://doi.org/10.3847%2F1538-3881%2Faa5e4d). [ISSN](/source/ISSN_(identifier)) [0004-6256](https://search.worldcat.org/issn/0004-6256).

1. **[^](#cite_ref-7)** Grav, T.; Bauer, J. M.; Mainzer, A. K.; Masiero, J. R.; Nugent, C. R.; Cutri, R. M.; Sonnett, S.; Kramer, E. (4 August 2015). ["NEOWISE: OBSERVATIONS OF THE IRREGULAR SATELLITES OF JUPITER AND SATURN"](https://iopscience.iop.org/article/10.1088/0004-637X/809/1/3). *The Astrophysical Journal*. **809** (1): 3. [arXiv](/source/ArXiv_(identifier)):[1505.07820](https://arxiv.org/abs/1505.07820). [Bibcode](/source/Bibcode_(identifier)):[2015ApJ...809....3G](https://ui.adsabs.harvard.edu/abs/2015ApJ...809....3G). [doi](/source/Doi_(identifier)):[10.1088/0004-637X/809/1/3](https://doi.org/10.1088%2F0004-637X%2F809%2F1%2F3). [ISSN](/source/ISSN_(identifier)) [1538-4357](https://search.worldcat.org/issn/1538-4357). [S2CID](/source/S2CID_(identifier)) [5834661](https://api.semanticscholar.org/CorpusID:5834661).

1. **[^](#cite_ref-Vilas_&_Hendrix_2024_8-0)** Vilas, Faith; Hendrix, Amanda R. (1 February 2024). ["Clues to the Origin of Jovian Outer Irregular Satellites from Reflectance Spectra"](https://iopscience.iop.org/article/10.3847/PSJ/ad150b). *The Planetary Science Journal*. **5** (2): 34. [Bibcode](/source/Bibcode_(identifier)):[2024PSJ.....5...34V](https://ui.adsabs.harvard.edu/abs/2024PSJ.....5...34V). [doi](/source/Doi_(identifier)):[10.3847/PSJ/ad150b](https://doi.org/10.3847%2FPSJ%2Fad150b). [ISSN](/source/ISSN_(identifier)) [2632-3338](https://search.worldcat.org/issn/2632-3338). [S2CID](/source/S2CID_(identifier)) [267531422](https://api.semanticscholar.org/CorpusID:267531422).

1. **[^](#cite_ref-SheppardJewittPorco2004_9-0)** [Sheppard, Scott S.](/source/Scott_S._Sheppard); [Jewitt, David C.](/source/David_Jewitt); [Porco, Carolyn](/source/Carolyn_Porco) (2004). ["Jupiter's outer satellites and Trojans"](https://web.archive.org/web/20070614045102/http://www.ifa.hawaii.edu/~jewitt/papers/JUPITER/JSP.2003.pdf) (PDF). In [Bagenal, Fran](/source/Fran_Bagenal); Dowling, Timothy E.; McKinnon, William B. (eds.). *Jupiter. The planet, satellites and magnetosphere*. Cambridge planetary science. Vol. 1. Cambridge, UK: [Cambridge University Press](/source/Cambridge_University_Press). pp. 263–280. [Bibcode](/source/Bibcode_(identifier)):[2004jpsm.book..263J](https://ui.adsabs.harvard.edu/abs/2004jpsm.book..263J). [ISBN](/source/ISBN_(identifier)) [0-521-81808-7](https://en.wikipedia.org/wiki/Special:BookSources/0-521-81808-7). [S2CID](/source/S2CID_(identifier)) [117582048](https://api.semanticscholar.org/CorpusID:117582048). Archived from [the original](http://www.ifa.hawaii.edu/~jewitt/papers/JUPITER/JSP.2003.pdf) (PDF) on 14 June 2007.

1. **[^](#cite_ref-scott_jupiter_10-0)** ["Moons of Jupiter"](https://sites.google.com/carnegiescience.edu/sheppard/moons/jupitermoons). *Earth & Planets Laboratory*. Carnegie Institution for Science. 25 January 2024.

1. **[^](#cite_ref-nasa_parameters_11-0)** ["Planetary Satellite Mean Elements"](https://ssd.jpl.nasa.gov/sats/elem/). *Jet Propulsion Laboratory*. California Institute of Technology. 25 January 2024.

## External links

v t e Moons of Jupiter Listed in increasing approximate distance from Jupiter Inner moons Metis Adrastea Amalthea Thebe Galilean moons Io Europa Ganymede Callisto Themisto Themisto Himalia group (11) Leda Ersa S/2018 J 2 Himalia Pandia Lysithea Elara S/2011 J 3 Dia +2 more Carpo group (2) S/2018 J 4 Carpo Valetudo Valetudo Ananke group (29) Euporie Jupiter LV Eupheme Jupiter LII Jupiter LIV Mneme Euanthe S/2003 J 16 Harpalyke Orthosie Helike Praxidike Jupiter LXIV S/2003 J 12 Jupiter LXVIII Thelxinoe Thyone Jupiter LXXIII Ananke Iocaste Hermippe Jupiter LXX +7 more Carme group (41) Jupiter LXIX Pasithee S/2003 J 24 Chaldene Jupiter LXIII Isonoe Kallichore Erinome Kale Eirene Aitne Eukelade Arche Taygete Jupiter LXXII Carme Herse Jupiter LXI Jupiter LI S/2003 J 9 Jupiter LXVI Kalyke S/2003 J 10 +18 more Pasiphae group (22) Philophrosyne Eurydome Jupiter LVI S/2003 J 4 Jupiter LXVII Hegemone Pasiphae Sponde Megaclite Cyllene Sinope Jupiter LIX Aoede Autonoe Callirrhoe S/2003 J 23 Kore +5 more See also Rings of Jupiter Jupiter's moons in fiction Category

---
Adapted from the Wikipedia article [Ananke group](https://en.wikipedia.org/wiki/Ananke_group) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Ananke_group?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.