| Discovery | |
|---|---|
| Discovered by | C. D. Perrine |
| Discovery date | January 2, 1905[1][2] |
| Mean orbit radius | 11,740,000 km (0.07810 AU)[3] |
| Eccentricity | 0.22[3] |
| Orbital period | 259.64 d (0.708 a)[3] |
| Average orbital speed | 3.27 km/s[3] |
| Inclination | 26.63° (to the ecliptic) 30.66° (to Jupiter's equator)[3] |
| Satellite of | Jupiter |
| Physical characteristics | |
| Mean radius | 43 km[4] |
| Surface area | ~23,200 km2 |
| Volume | ~333,000 km3 |
| Mass | 8.7 × 1017 kg |
| Mean density | 2.6 g/cm3 (assumed)[4] |
| Equatorial surface gravity | ~0.031 m/s2 (0.003 g) |
| Escape velocity | ~0.052 km/s |
| Sidereal rotation period | ~0.5 d (12 h) |
| Albedo | 0.04 (assumed)[4] |
| Temperature | ~124 K |
| | |
Elara (pronounced /ˈɛlərə/ EL-ər-ə, or as in Greek Ελάρα) is a prograde irregular satellite of Jupiter. It was discovered by Charles Dillon Perrine at Lick Observatory inr is also the eigth largest moon of Jupiter. 1905[1][2] and is named after the mother by Zeus of the giant Tityus. I[5]
Elara did not receive its present name until 1975; before then, it was simply known as Jupiter VII. It was sometimes called "Hera"[6] between 1955 and 1975.
Elara belongs to the Himalia group, five moons orbiting between 11 and 13 Gm from Jupiter at an inclination of about 27.5°.[3] Its orbital elements are as of January 2000. They are continuously changing due to Solar and planetary perturbations.
New Horizons encounter
In February and March 2007, the New Horizons spacecraft to Pluto captured Elara in several LORRI images from a distance of five million miles, helping to determine its shape.
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