Helene
From Space Wiki
| File:Cassini Helene N00051429 CL.png | |
| 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 [1] |
| 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.
File:Helene moon.jpg
Voyager 2 image of Helene.
[edit] External links
| 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: Pronunciation key | Rings of Saturn | Cassini-Huygens | Themis |
