Moons of Saturn

Saturn has 293 moons with confirmed orbits as of 17 June 2026, the most of any planet in the Solar System. Saturn's moons are diverse in size, ranging from tiny moonlets to Titan, which is larger than the planet Mercury and the second largest moon in the Solar System. Three of these moons possess particularly notable features: Titan has a nitrogen-rich 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; and Iapetus has contrasting black and white hemispheres as well as an extensive ridge of equatorial mountains which are among the tallest in the Solar System. Twenty-five of the confirmed moons are regular satellites; they have prograde orbits not greatly inclined to Saturn's equatorial plane (except Iapetus, which has a prograde but significantly inclined orbit). They include the seven rounded satellites, and four small moons that exist in a trojan orbit with some of the large moons. Four orbit inside of the diffuse G ring or between the major moons Mimas and Enceladus. Two moons are mutually co-orbital, Janus and Epimetheus. The relatively large Hyperion is locked in an orbital resonance with Titan. The remaining regular moons orbit near the edges of or within gaps in the main rings, some of which act as shepherd moons of the dense A Ring and the narrow F Ring. The regular satellites are traditionally named after Titans and Titanesses or other figures associated with the mythological Saturn, and two, S/2009 S 1 and S/2009 S 2, remain unnamed. The remaining 268 moons, with mean diameters ranging from 2 to 213 km (1 to 132 mi), orbit much farther from Saturn. They are irregular satellites, which have high orbital inclinations and eccentricities mixed between prograde and retrograde. These moons are probably captured minor planets, or fragments from the collisional breakup of such bodies after they were captured, creating collisional families. The irregular satellites are classified by their orbital characteristics into the prograde Inuit and Gallic groups and the large retrograde Norse group, and their names are chosen from the corresponding mythologies (with the Gallic group corresponding to Celtic mythology). Phoebe, the largest irregular Saturnian moon, is the sole exception to this naming system; it is part of the Norse group but named for a Greek Titaness. As of April 2026, 228 of Saturn's irregular moons are unnamed. The rings of Saturn are made of objects ranging in size from microscopic to moonlets hundreds of meters across, each in its own orbit around Saturn. The number of moons given above does not include these moonlets, nor hundreds of possible kilometer-sized distant moons that have been observed on single occasions. Thus an absolute number of Saturnian moons cannot be given, because there is no consensus on a boundary between the countless small unnamed objects that form Saturn's ring system and the larger objects that have been named as moons. Over 150 moonlets embedded in the rings have been detected by the disturbance they create in the surrounding ring material, though this is thought to be only a small sample of the total population of such objects.

Discovery

Early observations

Before the advent of telescopic photography, eight moons of Saturn were discovered by direct observation using optical telescopes. Saturn's largest moon, Titan, was discovered in 1655 by Christiaan Huygens using a 57-millimeter (2.2 in) objective lens on a refracting telescope of his own design. Tethys, Dione, Rhea and Iapetus (the "Sidera Lodoicea") were discovered between 1671 and 1684 by Giovanni Domenico Cassini. Mimas and Enceladus were discovered in 1789 by William Herschel. Hyperion was discovered in 1848 by W. C. Bond, G. P. Bond and William Lassell. The use of long-exposure photographic plates made possible the discovery of additional moons. The first to be discovered in this manner, Phoebe, was found in 1899 by W. H. Pickering. In 1966 the tenth satellite of Saturn was discovered by Audouin Dollfus, when the rings were observed edge-on near an equinox. It was later named Janus. A few years later it was realized that all observations of 1966 could only be explained if another satellite had been present and that it had an orbit similar to that of Janus. This object is now known as Epimetheus, the eleventh moon of Saturn. It shares the same orbit with Janus—the only known example of co-orbitals in the Solar System. In 1980, three additional Saturnian moons were discovered from the ground and later confirmed by the Voyager probes. They are trojan moons of Dione (Helene) and Tethys (Telesto and Calypso).

Observations by spacecraft

The study of the outer planets has since been revolutionized by the use of uncrewed space probes. The arrival of the Voyager spacecraft at Saturn in 1980–1981 resulted in the discovery of three additional moons—Atlas, Prometheus and Pandora—bringing the total to 17. In addition, Epimetheus was confirmed as distinct from Janus. In 1990, Pan was discovered in archival Voyager images. The Cassini mission, which arrived at Saturn in July 2004, initially discovered three small inner moons: Methone and Pallene between Mimas and Enceladus, and the second trojan moon of Dione, Polydeuces. It also observed three suspected but unconfirmed moons in the F Ring. In November 2004 Cassini scientists announced that the structure of Saturn's rings indicates the presence of several more moons orbiting within the rings, although only one, Daphnis, had been visually confirmed at the time. In 2007 Anthe was announced. In 2008 it was reported that Cassini observations of a depletion of energetic electrons in Saturn's magnetosphere near Rhea might be the signature of a tenuous ring system around Saturn's second largest moon. In March 2009, Aegaeon, a moonlet within the G Ring, was announced. In July of the same year, S/2009 S 1, the first moonlet within the B Ring, was observed. Cassini also observed another B ring moonlet, S/2009 S 2, though it was reported much later in June 2026. In April 2014, the possible beginning of a new moon, within the A Ring, was reported. (related image)

Search for irregulars

… excerpt ends here. Continue reading the full article.