Telesto is a moon of Saturn. It was discovered by Smith, Reitsema, Larson and Fountain in 1980 from ground-based observations, and was provisionally designated S/1980 S 13. In the following months, several other apparitions were observed: S/1980 S 24, S/1980 S 33, and S/1981 S 1.
Atlas is an inner satellite of Saturn which was discovered by Richard Terrile in 1980 from Voyager photos and was designated S/1980 S 28. In 1983 it was officially named after Atlas of Greek mythology, because it "holds the rings on its shoulders" like the Titan Atlas held the sky up above the Earth. It is also designated Saturn XV.
Rhea is the second-largest moon of Saturn and the ninth-largest moon in the Solar System, with a surface area that is comparable to the area of Australia. It is the smallest body in the Solar System for which precise measurements have confirmed a shape consistent with hydrostatic equilibrium. Rhea has a nearly circular orbit around Saturn, but it is also tidally locked, like Saturn's other major moons; that is, it rotates with the same period it revolves (orbits), so one hemisphere always faces towards the planet.
Helene is a moon of Saturn. It was discovered by Pierre Laques and Jean Lecacheux in 1980 from ground-based observations at Pic du Midi Observatory, and was designated S/1980 S 6. In 1988 it was officially named after Helen of Troy, who was the granddaughter of Cronus (Saturn) in Greek mythology. Helene is also designated Saturn XII (12), which it was given in 1982, and Dione B, because it is co-orbital with Dione and located in its leading Lagrangian point (L4). It is one of four known trojan moons.
Tethys, or Saturn III, is the fifth-largest moon of Saturn, measuring about 1,060 km (660 mi) across. It was discovered by Giovanni Domenico Cassini in 1684, and is named after the titan Tethys of Greek mythology.
Thebe, also known as Jupiter XIV, is the fourth of Jupiter's moons by distance from the planet. It was discovered by Stephen P. Synnott in images from the Voyager 1 space probe taken on March 5, 1979, while making its flyby of Jupiter. In 1983, it was officially named after the mythological nymph Thebe.
Iapetus is the outermost of Saturn's large moons. With an estimated diameter of 1,469 km (913 mi), it is the third-largest moon of Saturn and the eleventh-largest in the Solar System. Named after the Titan Iapetus, the moon was discovered in 1671 by Giovanni Domenico Cassini.
Janus is an inner satellite of Saturn. It is also known as Saturn X. It is named after the mythological Janus. This natural satellite was first identified by Audouin Dollfus on December 15, 1966, although it had been unknowingly photographed earlier by Jean Texereau. Further observations led to the realization that Janus shares a unique orbital relationship with another moon, Epimetheus. The discovery of these two moons' peculiar co-orbital configuration was later confirmed by Voyager 1 in 1980.
Epimetheus is an inner satellite of Saturn. It is also known as Saturn XI. It is named after the mythological Epimetheus, brother of Prometheus.
Calypso is a moon of Saturn. It was discovered in 1980, from ground-based observations, by Dan Pascu, P. Kenneth Seidelmann, William A. Baum, and Douglas G. Currie, and was provisionally designated S/1980 S 25. Several other apparitions of it were recorded in the following months: S/1980 S 29, S/1980 S 30, S/1980 S 32, and S/1981 S 2. In 1983 it was officially named after Calypso of Greek mythology. It is also designated Saturn XIV or Tethys C.
Dione, also designated Saturn IV, is the fourth-largest moon of Saturn. With a mean diameter of 1,123 km and a density of about 1.48 g/cm3, Dione is composed of an icy mantle and crust overlying a silicate rocky core, with rock and water ice roughly equal in mass. Its trailing hemisphere is marked by large cliffs and scarps called chasmata; the trailing hemisphere is also significantly darker compared to the leading hemisphere.
Mimas, also designated Saturn I, is the seventh-largest natural satellite of Saturn. With a mean diameter of 396.4 kilometres or 246.3 miles, Mimas is the smallest astronomical body known to be roughly rounded in shape due to its own gravity. Mimas's low density, 1.15 g/cm3, indicates that it is composed mostly of water ice with only a small amount of rock, and study of Mimas's motion suggests that it may have a liquid ocean beneath its surface ice. The surface of Mimas is heavily cratered and shows little signs of recent geological activity. A notable feature of Mimas's surface is Herschel, one of the largest craters relative to the size of the parent body in the Solar System. Herschel measures 139 kilometres across, about one-third of Mimas's mean diameter, and formed from an extremely energetic impact event. The crater's name is derived from the discoverer of Mimas, William Herschel, in 1789. The moon's presence has created one of the largest 'gaps' in Saturn's ring, named the Cassini Division, due to orbital resonance destabilising the particles' orbit there.
Prometheus is an inner satellite of Saturn. It was discovered on 24 October 1980 from images taken by the Voyager 1 probe, and was provisionally designated S/1980 S 27.
The moons of Saturn are numerous and diverse, ranging from tiny moonlets only tens of meters across to the enormous Titan, which is larger than the planet Mercury. There are 146 moons with confirmed orbits, the most of any planet in the solar system. This number does not include the many thousands of moonlets embedded within Saturn's dense rings, nor hundreds of possible kilometer-sized distant moons that have been observed on single occasions. Seven Saturnian moons are large enough to have collapsed into a relaxed, ellipsoidal shape, though only one or two of those, Titan and possibly Rhea, are currently in hydrostatic equilibrium. Three moons are particularly notable. Titan is the second-largest moon in the Solar System, with a nitrogen-rich Earth-like atmosphere and a landscape featuring river networks and hydrocarbon lakes. Enceladus emits jets of ice from its south-polar region and is covered in a deep layer of snow. Iapetus has contrasting black and white hemispheres as well as an extensive ridge of equatorial mountains among the tallest in the solar system.
Methone is a small, egg-shaped natural satellite of Saturn that orbits out past Saturn's ring system, between the orbits of Mimas and Enceladus. It was discovered in 2004, though it wasn't until 2012 that it was imaged in detail by the Cassini spacecraft.
Pallene is a very small natural satellite of Saturn. It is one of three small moons known as the Alkyonides that lie between the orbits of the larger Mimas and Enceladus. It is also designated Saturn XXXIII.
Ithaca Chasma is a valley (graben) of Saturn's moon Tethys, named after the island of Ithaca, in Greece. It is up to 100 km (62 mi) wide, 3–5 km (1.9–3.1 mi) deep and 2,000 km (1,200 mi) long, running approximately three-quarters of the way around Tethys' circumference, making it one of the longer valleys in the Solar System. Ithaca Chasma is approximately concentric with Odysseus crater.
Polydeuces, also designated Saturn XXXIV, is a small trojan moon of Saturn occupying the trailing L5 Lagrange point of Dione. It was discovered by the Cassini Imaging Science Team in images taken by the Cassini space probe on 21 October 2004. With a mean diameter of about 3 km (1.9 mi), Polydeuces is thought to have a smooth surface coated with fine, icy particles accumulated from the cryovolcanic plumes of Enceladus. In its orbit around Saturn, Polydeuces periodically drifts away from Dione's Lagrange point due to gravitational perturbations by other nearby moons of Saturn. Of the four known trojan moons of Saturn, Polydeuces exhibits the largest displacement from its Lagrange point.
Daphnis is an inner satellite of Saturn. It is also known as Saturn XXXV; its provisional designation was S/2005 S 1. Daphnis is about 8 kilometers in diameter, and orbits the planet in the Keeler Gap within the A ring.
Aegaeon, or Saturn LIII, is a natural satellite of Saturn. It has an extremely elongated shape whose surface is thought to be similarly smooth as Methone. It orbits between Janus and Mimas within Saturn's G Ring.
