Space · Moons

Ananke

A moon of Jupiter — Namesake of the Ananke group of retrograde Jovian outer moons.

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Quick facts

Parent planet

Jupiter

Diameter (mean)

28 km

Mass

3.0 × 10¹⁶ kg
4.1e-07 Moon masses

Mean orbital radius

21,276,000 km

Orbital period

629.8 Earth days

Discovery year

1951

Discoverer

Seth Barnes Nicholson

Naming origin

Greek personification of necessity

Surface conditions

Ananke is a 28-km retrograde irregular moon, namesake of the Ananke group of moons orbiting Jupiter at similar inclinations and distances. Like Carme and Pasiphae, the group is thought to be the fragmented remains of a single captured body.

Missions and observations

Every Jupiter-system mission has had an opportunity to image or characterize Ananke. The list below is the Jupiter-system mission catalog; specific Ananke encounters are documented in mission archives.

Mission	Year at Jupiter	Status
Pioneer 10 NASA	1973	Completed
Pioneer 11 NASA	1974	Completed
Voyager 1 NASA	1979	Completed
Voyager 2 NASA	1979	Completed
Ulysses NASA/ESA	1992	Completed
Galileo NASA	1995	Completed
Cassini-Huygens NASA/ESA/ASI	2000	Completed
New Horizons NASA	2007	Completed
Juno NASA	2016	Active
Europa Clipper NASA	2030	On the way
JUICE ESA	2031	On the way

Naming etymology

Ananke was the Greek personification of inevitability and necessity, mother of the Fates. The IAU adopted the name in 1975 — Nicholson had referred to the moon only by its provisional designation S/1951 J 2 for nearly a quarter century.

Methodology & sources

Diameter, mass, and orbital parameters from JPL Solar System Dynamics — Physical Parameters. Discovery year and discoverer from the JPL Satellite Discovery Circumstances. Naming etymology from the IAU Working Group for Planetary System Nomenclature. Stylized SVG hero composed from NASA / JPL imagery as visual reference; no photographs are reproduced.