Prometheus is an inner satellite of

Saturn Saturn is the sixth planet from the Sun and the second largest in the Solar System, after Jupiter. It is a gas giant, with an average radius of about 9 times that of Earth. It has an eighth the average density of Earth, but is over 95 tim ...

. It was discovered on 24 October 1980 from images taken by the ''

Voyager 1 ''Voyager 1'' is a space probe launched by NASA on September 5, 1977, as part of the Voyager program to study the outer Solar System and the interstellar medium, interstellar space beyond the Sun's heliosphere. It was launched 16 days afte ...

'' probe, and was provisionally designated . In late 1985 it was officially named after

Prometheus In Greek mythology, Prometheus (; , , possibly meaning "forethought")Smith"Prometheus". is a Titans, Titan. He is best known for defying the Olympian gods by taking theft of fire, fire from them and giving it to humanity in the form of technol ...

, a

Titan Titan most often refers to: * Titan (moon), the largest moon of Saturn * Titans, a race of deities in Greek mythology Titan or Titans may also refer to: Arts and entertainment Fictional entities Fictional locations * Titan in fiction, fictiona ...

Greek mythology Greek mythology is the body of myths originally told by the Ancient Greece, ancient Greeks, and a genre of ancient Greek folklore, today absorbed alongside Roman mythology into the broader designation of classical mythology. These stories conc ...

. It is also designated . Prometheus is extremely elongated, measuring approximately . It has several ridges and valleys and a number of

impact crater An impact crater is a depression (geology), depression in the surface of a solid astronomical body formed by the hypervelocity impact event, impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal c ...

s of about diameter are visible, but it is less cratered than nearby

Pandora In Greek mythology, Pandora was the first human woman created by Hephaestus on the instructions of Zeus. As Hesiod related it, each god cooperated by giving her unique gifts. Her other name—inscribed against her figure on a white-ground '' ky ...

Epimetheus In Greek mythology, Epimetheus (; ) is the brother of Prometheus, the pair serving "as representatives of mankind". Both sons of the Titan Iapetus, while Prometheus ("foresight") is ingeniously clever, Epimetheus ("hindsight") is inept and fool ...

, and

Janus In ancient Roman religion and myth, Janus ( ; ) is the god of beginnings, gates, transitions, time, duality, doorways, passages, frames, and endings. He is usually depicted as having two faces. The month of January is named for Janus (''Ianu ...

. From its very low density and relatively high

albedo Albedo ( ; ) is the fraction of sunlight that is Diffuse reflection, diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects ...

, 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.

Interactions with F Ring and other moons

Prometheus is a shepherd satellite for the inner edge of Saturn's narrow F Ring.

orbits just outside the F Ring, and has traditionally been viewed as an outer shepherd of the ring; however, recent studies indicate that only Prometheus contributes to the confinement of the ring. Images from the ''Cassini'' probe show that Prometheus's gravitational influence creates kinks and knots in the F Ring as it shepherds material from it. The orbit of Prometheus appears to be chaotic, due to a series of four 121:118 mean-motion resonances with

. The most appreciable changes in their orbits occur approximately every 6.2 years, when the

periapsis An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values. Apsides perta ...

of Pandora lines up with the apoapsis of Prometheus, as they approach to within approximately 1400 km. Prometheus is itself a significant perturber of

Atlas An atlas is a collection of maps; it is typically a bundle of world map, maps of Earth or of a continent or region of Earth. Advances in astronomy have also resulted in atlases of the celestial sphere or of other planets. Atlases have traditio ...

, with which it is in a 53:54 mean-longitude resonance.

Selected images

Animations

Notes

References

Citations

Sources

* * * * * * * *

External links

*
Prometheus Profile
a
NASA's Solar System Exploration site

3-D
anaglyph view of Prometheus {{DEFAULTSORT:Prometheus (Moon) Moons of Saturn Astronomical objects discovered in 1980 Articles containing video clips Prometheus Discoveries by Stewart A. Collins Moons with a prograde orbit