Atlas 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 ...

which was discovered by Richard Terrile in 1980 from Voyager photos and was designated . In 1983 it was officially named after

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 ...

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 ...

, because it "holds the rings on its shoulders" like the

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 ...

Atlas held the sky up above the

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

. It is also designated . Atlas is the closest satellite to the sharp outer edge of the A ring, and was long thought to be a shepherd satellite for this ring. However, now it is known that the outer edge of the ring is instead maintained by a 7:6

orbital resonance In celestial mechanics, orbital resonance occurs when orbiting bodies exert regular, periodic gravitational influence on each other, usually because their orbital periods are related by a ratio of small integers. Most commonly, this relation ...

with the larger but more distant moons

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 ...

and

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 ...

. In 2004 a faint, thin ring, temporarily designated , was discovered in the Atlantean orbit. High-resolution images taken in June 2005 by '' Cassini'' revealed Atlas to have a roughly spherical centre surrounded by a large, smooth equatorial ridge. The most likely explanation for this unusual and prominent structure is that ring material swept up by the moon accumulates on the moon, with a strong preference for the equator due to the ring's thinness. The size of the equatorial ridge is comparable with the expected

Roche lobe In astronomy, the Roche lobe is the region around a star in a binary system within which orbiting material is gravitationally bound to that star. It is an approximately teardrop-shaped region bounded by a critical gravitational equipotential, ...

of the moon, which means that for any additional particles impacting the equator, the

centrifugal force Centrifugal force is a fictitious force in Newtonian mechanics (also called an "inertial" or "pseudo" force) that appears to act on all objects when viewed in a rotating frame of reference. It appears to be directed radially away from the axi ...

will nearly overcome Atlas's tiny gravity, and they will probably be lost. Atlas is significantly perturbed by

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 ...

and to a lesser degree by

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 ...

, 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. Because the orbits of Prometheus and Pandora are chaotic, it is suspected that Atlas's may be as well.

Gallery

File:Cassini Atlas N00084634 CL.png, Atlas from above its south pole (June 12, 2007) File:Atlas Rev09.2x.jpg, Atlas - ''Cassini''
(June 8, 2005). File:Atlas with rings.jpg, Atlas - A and F rings
(June 30, 2006). File:PIA17206-SaturnMoon-Atlas-Flyby-20151206.jpg, Atlas near the A ring
(December 6, 2015). File:F Ring and Atlas PIA10448.jpg, Atlas near the F ring
(May 9, 2005).

Notes

References

Citations

Sources

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External links

Atlas Profile
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NASA's Solar System Exploration

NASA factsheet
{{DEFAULTSORT:Atlas (Moon) Moons of Saturn Astronomical objects discovered in 1980 Atlas (mythology) Moons with a prograde orbit