Elara (moon)
| Elara | |
|---|---|
|
|
| Elara (marked) | |
| Central body | Jupiter |
| Properties of the orbit | |
| Major semi-axis | 11,741,000 km |
| Periapsis | 9,188,500 km |
| Apoapsis | 14,293,500 km |
| eccentricity | 0.2174 |
| Orbit inclination | 26.627 ° |
| Orbital time | 259.64 d |
| Mean orbital velocity | 3.25 km / s |
| Physical Properties | |
| Albedo | 0.04 |
| Apparent brightness | 16.32 mag |
| Medium diameter | 86 km |
| Dimensions | 8.66 × 10 17 kg |
| Medium density | 2.6 g / cm 3 |
| Sidereal rotation | ? |
| Acceleration of gravity on the surface | 0.031 m / s 2 |
| Escape speed | 52 m / s |
| discovery | |
| Explorer | |
| Date of discovery | January 2, 1905 |
Elara (also Jupiter VII) is the second largest of the outer or irregular moons of the planet Jupiter .
discovery
Elara was discovered on January 2, 1905 by the astronomer Charles Dillon Perrine at the Lick Observatory ( San Jose , California ).
The moon was named after Elara , a lover of Zeus from Greek mythology . Elara received its official name in 1975 , previously it was referred to as Jupiter VII.
Orbit data
Elara orbits Jupiter at an average distance of 11,741,000 km in 259.64 days. The orbit has an eccentricity of about 0.22 and is inclined at 26.6 ° with respect to the local Laplace plane , which roughly coincides with the plane of the orbit of Jupiter.
Due to its orbital properties, it is assigned to the Himalia group , named after the Jupiter moon Himalia .
Physical data
Elara has a mean diameter of 86 km. Its density is relatively high at 2.6 g / cm³, which indicates that it is mainly composed of silicate rock. It has a very dark surface with an albedo of 0.04, i.e. that is, only 4% of the incident sunlight is reflected. Their apparent brightness is 16.3 m .
Web links
- Harvard College Observatory Bulletin , No. 178 (February 27, 1905), p. 1 (discovery)
- CD Perrine: "The Sixth Satellite of Jupiter", in: Publications of the Astronomical Society of the Pacific , Vol. 17 (1905), No. 101, p. 62
- CD Perrine: "Orbits of the Sixth and Seventh Satellites of Jupiter", in: Astronomische Nachrichten , Volume 169 (1905), Sp. 43-44.
- IAUC 2846: Satellites of Jupiter October 7, 1975 (designation)
| before | Jupiter moons | after that |
| Himalia | Elara |
Pasiphae |