Elara (moon)
 Elara near the glare of bright Jupiter |
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| Discovery | |
|---|---|
| Discovered by | C. D. Perrine |
| Discovery date | January 2, 1905[1][2] |
| Orbital characteristics | |
| 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 |
| Apparent magnitude | 16.3[4] |
Elara (pron.: /ˈɛlərə/ EL-ər-ə; Greek: Ελάρα) is a prograde irregular satellite of Jupiter. It was discovered by Charles Dillon Perrine at Lick Observatory in 1905.[1][2] It is the eighth largest moon of Jupiter and is named after Elara, one of Zeus's lovers and the mother of the giant Tityos.[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.
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New Horizons encounter [edit]
In February and March 2007, the New Horizons spacecraft to Pluto captured Elara in several LORRI images from a distance of five million miles.
See also [edit]
References [edit]
- ^ a b Perrine, C. D. (1905-02-27). "Satellites of Jupiter". Harvard College Observatory Bulletin 178.
- ^ a b Perrine, C. D. (1905). "The Seventh Satellite of Jupiter". Publications of the Astronomical Society of the Pacific 17 (101): 62–63. JSTOR 40691209.
- ^ a b c d e f Jacobson, R. A. (2000). "The orbits of outer Jovian satellites". Astronomical Journal 120 (5): 2679–2686. Bibcode:2000AJ....120.2679J. doi:10.1086/316817.
- ^ a b c d "Planetary Satellite Physical Parameters". JPL (Solar System Dynamics). 2009-04-03. Retrieved 2009-08-10.
- ^ Marsden, B. G. (7 October 1974). "Satellites of Jupiter". IAUC Circular 2846.
- ^ Payne-Gaposchkin, Cecilia; Katherine Haramundanis (1970). Introduction to Astronomy. Englewood Cliffs, N.J.: Prentice-Hall. ISBN 0-13-478107-4.
External links [edit]
- Elara on 1998-08-15 03:21 UTC (Crédit : OHP/IMCCE/CNRS)
- SkyView 23 47 09 -02 40 46
- HORIZONS Web-Interface
- Elara Profile by NASA's Solar System Exploration
- David Jewitt pages
- Jupiter's Known Satellites (by Scott S. Sheppard)
- Two Irregular Satellites of Jupiter (Himalia & Elara : Remanzacco Observatory : November 23, 2012)
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