Prometheus (moon)
Prometheus /prəˈmiːθiːəs/ is an inner satellite of Saturn. It was discovered in 1980 (on October 24) from photos taken by the Voyager 1 probe, and was provisionally designated S/1980 S 27.
Prometheus image from Cassini (December 26, 2009) | |
| Discovery | |
|---|---|
| Discovered by | Stewart A. Collins D. Carlson Voyager 1 |
| Discovery date | October, 1980 |
| Designations | |
Designation | Saturn XVI |
| Pronunciation | /prəˈmiːθiːəs/ |
Named after | Προμηθεύς Promētheys |
| Adjectives | Promethean, -ian /prəˈmiːθiːən/ |
| Orbital characteristics | |
| Epoch 31 December 2003 (JD 2453005.5) | |
| 139380±10 km | |
| Eccentricity | 0.0022 |
| 0.612990038 d | |
| Inclination | 0.008°±0.004° to Saturn's equator |
| Satellite of | Saturn |
| Group | Inner shepherd moon of the F Ring |
| Physical characteristics | |
| Dimensions | 137.0 × 81.0 × 56.2 km (± 1.0 × 2.8 × 0.8 km): 2 |
Mean diameter | 85.6±1.4 km: 2 |
| Volume | 327740±1710 km3: 4 |
| Mass | (1.59720±0.00072)×1017 kg |
Mean density | 0.4873±0.0026 g/cm3: 4 |
| 0.0007–0.0056 m/s2: 3 | |
| 0.018 km/s at longest axis to 0.028 km/s at poles | |
| synchronous | |
| zero | |
| Albedo | 0.6 |
| Temperature | ≈ 74 K |
In late 1985 it was officially named after Prometheus, a Titan in Greek mythology. It is also designated Saturn XVI.
Prometheus is extremely elongated, measuring approximately 137 km × 81 km × 56 km (85 mi × 50 mi × 35 mi). It has several ridges and valleys and a number of impact craters of about 20 km (12 mi) diameter are visible, but it is less cratered than nearby Pandora, Epimetheus, and Janus. From its very low density and relatively high albedo, it is likely that Prometheus is a very porous icy body. There is much uncertainty in these values, however, and so this remains to be confirmed.