Its estimated temperature is around 81 K, hotter than the other shepherd moons.Ītlas orbits around 137,000 km from its parent planet, Saturn. With a diameter of 30 km, Atlas is smaller than Earth by about 421.9 times but nearly four times bigger than the moon Daphnis. Even though they lie farther from the A ring, it is their orbital resonance that keeps the ring’s shape in check and not the gravitational influence of Atlas. The satellites Janus and Epimetheus are larger than Atlas. It was discovered that the edge of the A ring is actually maintained by the co-orbital moons Janus and Epimetheus. It was later found out that the moon’s responsibility was not that big after all. The same was also thought of with the namesake moon. In Greek mythology, Atlas was given the obligation to hold up the weight of the sky forever on his shoulders. Surely, someone with an equally important task! Keeping the outer A ring sharp is a great responsibility, so this moon was named after the Titan Atlas. It acts as a ring shepherd, or so it was thought. It has a red spectrum but not as red as the moon Pan.Ītlas orbits close to the outer bounds of the A ring and helps maintain its outer edge. The smooth edge of this moon stands in contrast with its rough and somewhat spherical core. It has an irregular shape which many likened to that of a flying saucer.
Scientist Richard Terrile discovered this satellite in October 1980 from Voyager 1 images.Ītlas is one of the inner satellites of Saturn. It is also known by the designation Saturn XV.
Behind the name – Ātlās (the Titan carrying the heaven on his back).Examples are Metis of Jupiter, Cordelia and Ophelia of Uranus, and Galatea of Neptune.Ītlas Moon: Facts and Figures All About the Name The other giant planets in the solar system, Jupiter, Uranus, and Neptune, keep their rings sharp with the help of their inner moons as well. Ring shepherds are not only found in the system of Saturn. Though they are not as close to the rings as the others, the co-orbital moons Janus and Epimetheus also function as herder moons. The other two shepherds, Prometheus and Pandora, maintain the F ring. Pan and Daphnis are within the Encke gap and the Keeler Gap respectively while Atlas lies close to the edge of the A ring. Saturn has three moons shepherding the A ring. These moons are also called herder moons and watcher moons. In a way, shepherd moons “herd” the ring materials of Saturn. That sort of “kick” sculpts the edge of Saturn’s rings or keeps the ring gaps open. Those materials are deflected by the gravitational influence of the moons, keeping them in place. A shepherd moon comes to the rescue when that happens.Īs shepherd satellites orbit their parent planet, they come across loose ring materials along the way. Because of the movement, particles can go off track and diverge from the ring. Saturn’s rings move and orbit around it at different speeds. Remember that planetary rings are made up of dust, ice, and all kinds of debris suspended in space. Ring shepherd moons help keep the shape of a planet’s ring.