Prometheus (moon)

Prometheus
Discovery
Discovered by Collins, Voyager 1
Discovered in October, 1980
Orbital characteristics
Semimajor axis 139,353 km
Eccentricity 0.0024
Orbital period 0.614102 d
Inclination 0.007° (to Saturn's equator)
Is a satellite of Saturn
Physical characteristics
Diameter 148×100×68 km
Surface area ~136,000 km2
Volume ~527,000 km3
Mass 3.3×1017 kg
Mean density 0.63 g/cm3
Surface gravity ~0.0081 m/s2
Escape velocity ~0.030 km/s
Rotation period synchronous
Axial tilt zero
Albedo 0.6
Surface temp.
min mean max
K ~74 K K
Atmosphere none

Prometheus (proe-mee'-thee-us, Greek Προμηθέας) is a moon of Saturn. It was discovered in 1980 (some time before October 25) from Voyager photos, and was designated 1980 S 27. In 1985 it was officially named after Prometheus, a Titan in Greek mythology. It is also designated as Saturn XVI.

This small moon is extremely elongated, measuring about 148 by 100 by 68 km. It has several ridges and valleys and a number of impact craters of about 20 km diameter are visible, but it is less cratered than nearby Pandora, Epimetheus and Janus. From its very low density and relatively high albedo, it seems likely that Prometheus is a very porous icy body. There is a lot of uncertainty in these values, however, and so this remains to be confirmed.


Closeup of Prometheus's gravitational effect on the F Ring

Prometheus acts as a shepherd satellite for the inner edge of Saturn's F Ring. Recent images from the Cassini probe show that the Promethean gravitational field creates kinks and knots in the F Ring as the moon 'steals' material from it.

There is also an asteroid called 1809 Prometheus.





Links

The Planetary Society: Prometheus



... | Atlas | Prometheus | S/2004 S 6 | ...



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: Rings of Saturn | Cassini-Huygens | Themis

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