Atlas (moon)
From Wikipedia, the free encyclopedia
 Atlas, as imaged by Cassini on June 8, 2005 |
|
| Discovery | |
|---|---|
| Discovered by: | Terrile, Voyager 1 |
| Discovery date: | October, 1980 |
| Orbital characteristics [1] | |
| Epoch 31 December 2003 (JD 2453005.5) | |
| Mean radius of orbit: | 137,670 ± 10 km |
| Eccentricity: | 0.0012 |
| Orbital period: | 0.6016947883 d |
| Inclination: | 0.003 ± 0.004° |
| Satellite of: | Saturn |
| Physical characteristics | |
| Dimensions: | 46 × 38 × 19 km [2] |
| Mean radius: | 15.3 ± 1.2 km [2] |
| Surface area: | ~3,700 km² |
| Volume: | ~15,000 km³ |
| Mass: | 6.6 ± 0.6 ×1015 kg [1] |
| Mean density: | 0.44 ± 0.11 g/cm³ |
| Equatorial surface gravity: | ~0.00083 m/s2 |
| Escape velocity: | ~0.0062 km/s |
| Rotation period: | synchronous |
| Axial tilt: | zero |
| Albedo: | 0.4 |
| Temperature: | ~81 K |
Atlas (at'-ləs, IPA: [/ˈætləs/], Greek Άτλας) is an inner satellite of Saturn.
Atlas was discovered by Richard Terrile in 1980 (some time before November 12) from Voyager photos and was designated S/1980 S 28. In 1983 it was officially named after Atlas of Greek mythology, because it "holds the rings on its shoulders" like the Titan Atlas held the sky up above the Earth. It is also designated as Saturn XV.
Atlas seems to be a shepherd satellite of the A ring. Furthermore, in 2004 a faint, thin ring, temporarily designated R/2004 S 1, was discovered within Atlas's orbit.
High-resolution images taken in June 2005 by Cassini reveal a saucer-shaped moon with a large equatorial ridge.
Atlas is significantly perturbed by Prometheus and to a lesser degree by Pandora, leading to excursions in longitude of up to 600 km (~0.25°) away from the precessing keplerian orbit with a rough period of about 3 years. Since the orbits of Prometheus and Pandora are chaotic, it is suspected that Atlas's may be as well [1].
[edit] References
- ^ a b c J.N. Spitale et al (2006). "The orbits of Saturn's small satellites derived from combined historic and Cassini imaging observations". The Astronomical Journal 132: 692.
- ^ a b C.C. Porco et al. (2006). "Physical characteristics and possible accretionary origins for Saturn's small satellites". Bulletin of the American Astronomical Society 37: 768.
[edit] External links
- The Planetary Society: Atlas
- NASA factsheet
- IAUC 3539, announcing (second-hand) the discovery of S/1980 S 28
| Moons of Saturn | |
|---|---|
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Generally listed in increasing distance from Saturn
|
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| Ring shepherds | Pan · Daphnis · Atlas · Prometheus · S/2004 S 6 · S/2004 S 4 · S/2004 S 3 · Pandora |
| Co-orbitals | Epimetheus · Janus |
| Inner large and Trojan | Mimas · Methone · Pallene · Enceladus · Tethys (trojans Telesto, Calypso) · Dione (trojans Helene, Polydeuces) |
| Outer large | Rhea · Titan · Hyperion · Iapetus |
| Inuit group | Kiviuq · Ijiraq · Paaliaq · Bebhionn · Siarnaq |
| Norse group | Phoebe · Skathi · Skoll · S/2004 S 13 · S/2006 S 4 · Hyrokkin · Mundilfari · S/2006 S 6 · S/2006 S 1 · S/2004 S 17 · Narvi · Bergelmir · Aegir · Suttungr · S/2004 S 12 · Bestla · Farbauti · Hati · S/2004 S 7 · Thrymr · S/2006 S 3 · Surtur · Kari · Fenrir · Ymir · Loge · Fornjot |
| Gallic group | Albiorix · Erriapo · Tarvos |
