Elara (moon)
From Wikipedia, the free encyclopedia
| Discovery | |
|---|---|
| Discovered by: | C. D. Perrine |
| Discovery date: | January 2, 1905 |
| Orbital characteristics | |
| Periapsis: | 9,670,500 km (0.065 AU) |
| Apoapsis: | 13,695,700 km (0.092 AU) |
| Mean radius of orbit: | 11,683,120 km (0.07810 AU) |
| Orbital circumference: | 72,859,500 km (0.487 AU) |
| Eccentricity: | 0.1723 |
| Orbital period: | 257.984888 d (0.706 a) |
| Avg. orbital speed: | 3.269 km/s |
| Max. orbital speed: | 3.919 km/s |
| Min. orbital speed: | 2.767 km/s |
| Inclination: | 29.20° (to the ecliptic) 30.66° (to Jupiter's equator) |
| 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 |
| 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 |
| Temperature: | ~124 K |
Elara (IPA: [ˈɛlərə], Attic Greek Ελάρα) is a prograde irregular satellite of Jupiter. It was discovered by Charles Dillon Perrine at Lick Observatory in 1905 and is named after the mother by Zeus of the giant Tityus.
Elara did not receive its present name until 1975; before then, it was simply known as Jupiter VII. It was sometimes called "Hera".
It belongs to the Himalia group, five moons orbiting between 11 and 13 Gm from Jupiter at an inclination of about 27.5°.
[edit] New Horizons encounter
In February and March 2007, the New Horizons spacecraft to Pluto will make a number of images of Elara, culminating in photos from a distance of five million miles.
[edit] External links
- Harvard College Observatory Bulletin, 178 (1905) 1
- Publications of the Astronomical Society of the Pacific, 17 (1905) 62
- Astronomische Nachrichten, 169 (1905) 43/44
| Moons of Jupiter | |
|---|---|
|
Listed in increasing distance from Jupiter. Italics indicate ungrouped moons.
|
|
| 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 | |
