Which small moon of Saturn is nicknamed a “flying saucer” because of its prominent equatorial ridge? Atlas is the answer.
Atlas has a roughly spherical central body surrounded by a broad, smooth ridge around its equator. The unusual silhouette resembles a flying saucer, making Atlas one of the most visually distinctive small moons in the Solar System. Cassini images taken in June 2005 revealed the ridge in high resolution.
The ridge is thought to have formed as Atlas swept up material from Saturn’s rings. Because the rings are extremely thin, particles preferentially accumulated around the moon’s equator. The structure extends about 20 to 50 degrees from the equator and accounts for roughly 25% of Atlas’s total volume.
Atlas was discovered by Richard Terrile in Voyager 1 images in 1980 and officially named in 1983 after the Titan Atlas of Greek mythology. It orbits close to the outer edge of Saturn’s A ring. Although once considered a possible shepherd moon, the A ring’s sharp edge is now understood to be maintained mainly by an orbital resonance involving Janus and Epimetheus.