Space · Moons

Elara

A moon of Jupiter — A Himalia-group outer irregular — the second-largest moon Perrine discovered at Lick Observatory.

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Quick facts

Parent planet

Jupiter

Diameter (mean)

79 km

Mass

8.7 × 10¹⁷ kg
1.18e-05 Moon masses

Mean orbital radius

11,740,000 km

Orbital period

259.6 Earth days

Discovery year

1905

Discoverer

Charles Dillon Perrine

Naming origin

Greek mortal princess, mother of giant Tityos by Zeus

Surface conditions

Elara is a dark, irregular body 79 km across in a highly inclined prograde orbit at 11.7 million km from Jupiter. Like other members of the Himalia group, Elara is probably a fragment of a captured asteroid that broke up after capture. No spacecraft has flown close enough for resolved imagery.

Missions and observations

Every Jupiter-system mission has had an opportunity to image or characterize Elara. The list below is the Jupiter-system mission catalog; specific Elara 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

Elara was a mortal princess in Greek mythology, lover of Zeus and mother of the giant Tityos. The IAU adopted the name in 1975.

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.