Helene (moon)
From Wikipedia, the free encyclopedia
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Discovery
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| Discovered by | Laques and Lecacheux |
| Discovery date | March 1, 1980 |
| Semi-major axis | 377,396 km |
| Eccentricity | 0.0022 |
| Orbital period | 2.736915 d [1] |
| Inclination | 0.199° (to Saturn's equator) |
| Satellite of | Saturn |
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Physical characteristics
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| Dimensions | 36 × 32 × 30 km |
| Mean radius | 16 km |
| Rotation period | assumed synchronous |
| Axial tilt | zero |
| Albedo | 1.67 ± 0.20 (geometric)[2] |
Helene (pronounced /ˈhɛlɨni/ HEL-ə-nee, sometimes /hɨˈliːni/ hə-LEE-nee, or as Greek Ἑλένη) 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.[3] In 1988 it was officially named after Helen of Troy, who was the granddaughter of Cronus (Saturn) in Greek mythology.[4] The moon is also designated Saturn XII, a number which it received in 1982, under the designation Dione B,[5] because it is co-orbital with Dione and located in its leading Lagrangian point (L4).
[edit] Exploration
The closest images of Helene are from the Cassini spacecraft's 36,000 km fly-by in 2007. Helene will be the target of a much closer fly-by (1800 km) during Cassini's extended mission on 2010 March 3.
[edit] Gallery
 Voyager 2 image of Helene. |
 Cassini-Huygens image taken February 2006 |
[edit] References
- ^ NASA Celestia
- ^ Verbiscer, A.; French, R.; Showalter, M.; and Helfenstein, P.; Enceladus: Cosmic Graffiti Artist Caught in the Act, Science, Vol. 315, No. 5813 (February 9, 2007), p. 815 (supporting online material, table S1)
- ^ IAUC 3496: Satellites of Saturn 1980 July 31 (discovery)
- ^ IAUC 4609: Satellites of Saturn and Uranus 1988 June 8 (naming the moon)
- ^ Transactions of the International Astronomical Union, Vol. XVIIIA, 1982 (mentioned in IAUC 3872: Satellites of Jupiter and Saturn, 1983 September 30)
[edit] External links
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