Space · Moons
Prometheus
A moon of Saturn — Saturn's F-ring shepherd — its gravity continuously sculpts the ring's inner edge.
Quick facts
Parent planet
Diameter (mean)
86 km
Mass
1.59 × 10¹⁷ kg
2.16e-06 Moon masses
Mean orbital radius
139,380 km
Orbital period
0.613 Earth days
Discovery year
1980
Discoverer
Stewart A. Collins (Voyager 1)
Naming origin
Titan who gave fire to humanity
Surface conditions
Prometheus is a 136×79×59 km irregular moon orbiting just inside Saturn's F ring. Its gravity perturbs the inner edge of the F ring, creating channels and streamers in the ring particles. Together with Pandora (which shepherds the F ring's outer edge), Prometheus is one of the two F-ring shepherd moons.
Missions and observations
Every Saturn-system mission has had an opportunity to image or characterize Prometheus. The list below is the Saturn-system mission catalog; specific Prometheus encounters are documented in mission archives.
| Mission | Year at Saturn | Status |
|---|---|---|
|
Pioneer 11 NASA |
1979 | Completed |
|
Voyager 1 NASA |
1980 | Completed |
|
Voyager 2 NASA |
1981 | Completed |
|
Cassini-Huygens NASA/ESA/ASI |
2004 | Completed |
|
Dragonfly NASA |
2034 | On the way |
Naming etymology
Prometheus was the Titan who stole fire from the gods and gave it to humanity, suffering eternal punishment for his rebellion. The IAU adopted the name in 1985.
Methodology & sources
Diameter, mass, and orbital parameters from JPL Solar System Dynamics — Physical Parameters. Discovery year and discoverer from the JPL Satellite Discovery Circumstances. Naming etymology from the IAU Working Group for Planetary System Nomenclature. Stylized SVG hero composed from NASA / JPL imagery as visual reference; no photographs are reproduced.