Helene (moon)
Helene /ˈhɛləniː/ is a moon of Saturn. It was discovered by Pierre Laques and Jean Lecacheux in 1980 from ground-based observations at Pic du Midi Observatory, and was designated S/1980 S 6. In 1988 it was officially named after Helen of Troy, who was the granddaughter of Cronus (Saturn) in Greek mythology. Helene is also designated Saturn XII (12), which it was given in 1982, and Dione B, because it is co-orbital with Dione and located in its leading Lagrangian point (L4). It is one of four known trojan moons.
| Discovery | |
|---|---|
| Discovered by | P. Laques J. Lecacheux |
| Discovery site | Pic du Midi Observatory |
| Discovery date | March 1, 1980 |
| Designations | |
Designation | Saturn XII |
| Pronunciation | /ˈhɛləniː/ |
Named after | Helen of Troy (Ἑλένη Helenē) |
| |
| Adjectives | Helenean /hɛləˈniːən/ |
| Orbital characteristics | |
| 377600 km | |
| Eccentricity | 0.007 |
| 2.736916 d | |
| Inclination | 0.199° (to Saturn's equator) |
| Satellite of | Saturn |
| Group | L4 Dione trojan |
| Physical characteristics | |
| Dimensions | 45.2 × 39.2 × 26.6 km (± 0.4 × 0.6 × 0.4 km) |
Mean diameter | 36.2±0.4 km |
| Volume | 24840 km3 |
| Mass | (7.1±0.2)×1015 kg |
Mean density | 0.2926±0.0217 g/cm3 |
| 0.0009 m/s2 at longest axis to 0.0027 m/s2 at poles | |
| 0.0065 km/s at longest axis to 0.0084 km/s at poles | |
| assumed synchronous | |
| zero | |
| Albedo | 1.67±0.20 (geometric) |
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