Elara (moon)
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| Discovery | |
|---|---|
| Discovered by: | C. D. Perrine |
| Discovery date: | January 2, 1905[1][2] |
| Orbital characteristics | |
| Mean radius of orbit: | 11,740,00 km (0.07810 AU)[3] |
| Eccentricity: | 0.22[3] |
| Orbital period: | 259.64 d (0.708 a)[3] |
| Avg. 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 |
| Surface area: | ~23,200 km2 |
| Volume: | ~333,000 km3 |
| Mass: | 8.7×1017 kg |
| Mean density: | 2.6 g/cm3 (assumed) |
| 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) |
| Temperature: | ~124 K |
Elara is a non-spherical moon of Jupiter. It was found by Charles Dillon Perrine at Lick Observatory in 1905[1][2] and is named after the mother by Zeus of the giant Tityus.[4]
Elara did not get its present name until 1975; before then, it was simply known as Jupiter VII. It was sometimes called "Hera"[5] between 1955 and 1975.
Elara belongs to the Himalia group, five moons orbiting between 11,000,000 and 13,000,000 km from Jupiter at an inclination of about 27.5°.[3] Its orbital elements are as of January 2000. They are changing a lot due to Solar and planetary perturbations.
[change] New Horizons encounter
In February and March 2007, the New Horizons spacecraft to Pluto made a number of pictures of Elara, culminating in photos from a distance of five million miles.
[change] References
- ↑ 1.0 1.1 Perrine, C. D. (1905 February 27). "Satellites of Jupiter". Harvard College Observatory Bulletin 178.
- ↑ 2.0 2.1 Perrine, C. D. (1905). "The Seventh Satellite of Jupiter". Publications of the Astronomical Society of the Pacific 17 (101): 62–63.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Jacobson, R. A. (2000). "The orbits of outer Jovian satellites". Astronomical Journal 120: 2679-2686. DOI:10.1086/316817.
- ↑ 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 0-134-78107-4.
[change] Other websites
| Moons of Jupiter | |
|---|---|
| Listed in increasing distance from Jupiter. Temporary names in italics. | |
| Amalthea group | Metis · Adrastea · Amalthea · Thebe |
| Galilean moons | Io · Europa · Ganymede · Callisto |
| Themisto | |
| Himalia group | Leda · Himalia · Lysithea · Elara · S/2000 J 11 |
| Carpo · S/2003 J 12 | |
| Ananke group | Ananke · Praxidike · Harpalyke · Iocaste · Euanthe · Thyone (core) Euporie · S/2003 J 3 · S/2003 J 18 · Thelxinoe · Helike · Orthosie · S/2003 J 16 · Hermippe · Mneme · S/2003 J 15 (peripheral) |
| Carme group | S/2003 J 17 · S/2003 J 10 · Pasithee · Chaldene · Arche · Isonoe · Erinome · Kale · Aitne · Taygete · S/2003 J 9 · Carme · S/2003 J 5 · S/2003 J 19 · Kalyke · Eukelade · Kallichore |
| Pasiphaë group | Eurydome · S/2003 J 23 · Hegemone · Pasiphaë · Sponde · Cyllene · Megaclite · S/2003 J 4 · Callirrhoe · Sinope · Autonoe · Aoede · Kore |
| S/2003 J 2 | |
