| Proper Name | Elara | | Designation | Jupiter VII | | Primary Planet | Jupiter | | Family / Class | Himalia group | | Orbital Period | 258 days, 16 hours | | Distance from Jupiter | Semi-Major Axis: 11,703,000 km
Periapsis: 9,408,000 km
Apoapsis: 13,999,000 km
| | Eccentricity | 0.1961 | | Rotation Period | 12 hours | | Mean Diameter | 79.9 km
49.6 miles | | Notes | A small, dark moon of Jupiter, but nevertheless the second largest member of the Himalia group. The moon's very low albedo of just 0.046 suggests that it is carbonaceous in nature, and that the entire group resulted from an asteroid being broken apart in the distant past by Jupiter's gravity. |
The second largest of a group of moons that orbit Jupiter beyond the Galilean moons at a distance of nearly twelve million kilometres from the giant planet. This group, known as the Himalia group after by far its largest member, is thought to have originated as an asteroid, captured and sheared apart by Jupiter's gravity. Himalia represents the bulk of the debris of this shattered asteroid, with Elara as the largest of the remaining shards. The other smaller members of the group are the moons Leda, Lysithea, and possibly also the tiny moon Dia.
Elara itself is a dark body, some eighty kilometres in diameter and therefore probably rather irregular in shape. It turns on its axis every twelve hours, and currently completes an orbit of Jupiter in a little under 260 days. All of the members of this group are highly affected by Jupiter's immense gravity, and this means that the characteristics of their eccentric orbits tend to change over time (indeed, it is possible that Elara has actually collided with other members of the group in the distant past).
|
|
