Helene (moon)

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**Helene**
Discovery

Discovered by	Laques and Lecacheux
Discovered in	March 1, 1980
Orbital characteristics
Semimajor axis	377,396 km
Eccentricity	0.0022
Orbital period	2.736915 d ^[link]
Inclination	0.199° (to Saturn's equator)
Satellite of	Saturn
Physical characteristics
Mean diameter	32 km (36 × 32 × 30)
Mass	?kg
Mean density	? g/cm³
Surface gravity	?m/s²
Escape velocity	?km/s
Rotation period	assumed synchronous
Axial tilt	zero
Albedo	?
Surface temperature	? K
Atmosphere	none

Helene (hel'-e-nee, sometimes he-lee'-nee, /ˈhɛləni/, /həˈliːni/, 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. In 1988 it was officially named after Helen of Troy, who was the granddaughter of Cronus (Saturn) in Greek mythology. The moon is also designated Saturn XII.

It is co-orbital with Dione and located in its leading Lagrangian point (L₄) and hence, before it received its permanent name it was usually referred to as Dione B.

Voyager 2 image of Helene.

External links

[The Planetary Society: Helene]

... | Calypso | Helene | Dione | ...

[http://encycl.opentopia.com/ edit ] Saturn's natural satellites
Pan \| Daphnis \| Atlas \| Prometheus \| S/2004 S 6 \| S/2004 S 4 \| S/2004 S 3 \| Pandora \| Epimetheus and Janus
Mimas \| Methone \| Pallene \| Enceladus \| Telesto, Tethys, and Calypso \| Polydeuces, Dione, and Helene \| Rhea
Titan \| Hyperion \| Iapetus \| Kiviuq \| Ijiraq \| Phoebe \| Paaliaq \| Skathi \| Albiorix \| S/2004 S 11 \| Erriapo \| Siarnaq
S/2004 S 13 \| Tarvos \| Mundilfari \| S/2004 S 17 \| Narvi \| S/2004 S 15 \| S/2004 S 10 \| Suttungr \| S/2004 S 12
S/2004 S 18 \| S/2004 S 9 \| S/2004 S 14 \| S/2004 S 7 \| Thrymr \| S/2004 S 16 \| Ymir \| S/2004 S 8
See also: [[Help:Pronunciation respelling key\|Pronunciation key]] \| Rings of Saturn \| Cassini-Huygens \| Themis

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