The moons of Saturn are numerous and diverse, ranging from tiny moonlets only tens of meters across to enormous Titan, which is larger than the planet Mercury. Saturn has 83 moons with confirmed orbits that are not embedded in its rings– of which only 13 have diameters greater than 50 kilometers – as well as dense rings that contain millions of embedded moonlets and innumerable smaller ring particles. Seven Saturnian moons are large enough to have collapsed into a relaxed, ellipsoidal shape, though only one or two of those, Titan and possiblyRhea, are currently in hydrostatic equilibrium. Particularly notable among Saturn's moons are Titan, the second-largest moon in the Solar System (after Jupiter's Ganymede), with a nitrogen-rich Earth-like atmosphere and a landscape featuring dry river networks and hydrocarbon lakes, Enceladus, which emits jets of gas and dust from its south-polar region, and Iapetus, with its contrasting black and white hemispheres.
Twenty-four of Saturn's moons are regular satellites; they have prograde orbits not greatly inclined to Saturn's equatorial plane.They include the seven major satellites, four small moons that exist in a trojan orbit with larger moons, two mutually co-orbital moons and two moons that act as shepherds of Saturn's F Ring. Two other known regular satellites orbit within gaps in Saturn's rings. The relatively large Hyperion is locked in a resonance with Titan. The remaining regular moons orbit near the outer edge of the A Ring, within G Ring and between the major moons Mimas and Enceladus. The regular satellites are traditionally named after Titans and Titanesses or other figures associated with the mythological Saturn.
The remaining fifty-nine, with mean diameters ranging from 4 to 213 km, are irregular satellites, whose orbits are much farther from Saturn, have high inclinations, and are mixed between prograde and retrograde. These moons are probably captured minor planets, or debris from the breakup of such bodies after they were captured, creating collisional families. The irregular satellites have been classified by their orbital characteristics into the Inuit, Norse, and Gallic groups, and their names are chosen from the corresponding mythologies, with two exceptions. One of these is Phoebe (part of the Norse group but named for a Greek Titaness), the ninth moon of Saturn and largest irregular, discovered at the end of the 19th century; the other is Bebhionn, which, though in the Gallic group, is named after an Irish goddess.
The rings of Saturn are made up of objects ranging in size from microscopic to moonlets hundreds of meters across, each in its own orbit around Saturn.Thus a precise number of Saturnian moons cannot be given, because there is no objective boundary between the countless small anonymous 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.
There are still 30 unnamed moons (as of November 2021 [update] ). If named, they will receive names from Gallic, Norse and Inuit mythology based on the orbital groups of the moons.
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).
The study of the outer planets has since been revolutionized by the use of unmanned 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, – 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. In April 2014, the possible beginning of a new moon, within the A Ring, was reported. (related image)which arrived at Saturn in the summer of 2004, initially discovered three small inner moons including Methone and Pallene between Mimas and Enceladus as well as the second trojan moon of Dione
Study of Saturn's moons has also been aided by advances in telescope instrumentation, primarily the introduction of digital charge-coupled devices which replaced photographic plates. For the 20th century, Phoebe stood alone among Saturn's known moons with its highly irregular orbit. Then in 2000, three dozen additional irregular moons have been discovered using ground-based telescopes. m telescope reported the discovery of nine more irregular moons, in April 2007, Tarqeq (S/2007 S 1) was announced and in May of the same year S/2007 S 2 and S/2007 S 3 were reported. In 2019, twenty new irregular satellites of Saturn were reported, resulting in Saturn overtaking Jupiter as the planet with the most known moons for the first time since 2000. Yet another was reported in 2021.A survey starting in late 2000 and conducted using three medium-size telescopes found thirteen new moons orbiting Saturn at a great distance, in eccentric orbits, which are highly inclined to both the equator of Saturn and the ecliptic. They are probably fragments of larger bodies captured by Saturn's gravitational pull. In 2005, astronomers using the Mauna Kea Observatory announced the discovery of twelve more small outer moons, in 2006, astronomers using the Subaru 8.2
Some of the 83 known satellites of Saturn are considered lost because they have not been observed since their discovery and hence their orbits are not known well enough to pinpoint their current locations.Work has been done to recover many of them in surveys from 2009 onwards, but four – S/2004 S 13, S/2004 S 17, S/2004 S 7, and S/2007 S 3 – still remain lost today.
The modern names for Saturnian moons were suggested by John Herschel in 1847.He proposed to name them after mythological figures associated with the Roman titan of time, Saturn (equated to the Greek Cronus). In particular, the then known seven satellites were named after Titans, Titanesses and Giants—brothers and sisters of Cronus. In 1848, Lassell proposed that the eighth satellite of Saturn be named Hyperion after another Titan. When in the 20th century the names of Titans were exhausted, the moons were named after different characters of the Greco-Roman mythology or giants from other mythologies. All the irregular moons (except Phoebe) are named after Inuit and Gallic gods and after Norse ice giants.
Some asteroids share the same names as moons of Saturn: 55 Pandora, 106 Dione, 577 Rhea, 1809 Prometheus, 1810 Epimetheus, and 4450 Pan. In addition, two more asteroids previously shared the names of Saturnian moons until spelling differences were made permanent by the International Astronomical Union (IAU): Calypso and asteroid 53 Kalypso; and Helene and asteroid 101 Helena.
Saturn's satellite system is very lopsided: one moon, Titan, comprises more than 96% of the mass in orbit around the planet. The six other planemo (ellipsoidal) moons constitute roughly 4% of the mass, and the remaining 75 small moons, together with the rings, comprise only 0.04%.
|Comparative masses of Saturn's moons|
|The relative masses of Saturn's moons. Values are ×1021 kg. With Titan in the comparison (left), Mimas and Enceladus are invisible at this scale. Even excluding Titan (right), Phoebe, Hyperion, the smaller moons and the rings are still invisible.|
|Saturn's major satellites, compared to the Moon|
Although the boundaries may be somewhat vague, Saturn's moons can be divided into ten groups according to their orbital characteristics. Many of them, such as Pan and Daphnis, orbit within Saturn's ring system and have orbital periods only slightly longer than the planet's rotation period.The innermost moons and most regular satellites all have mean orbital inclinations ranging from less than a degree to about 1.5 degrees (except Iapetus, which has an inclination of 7.57 degrees) and small orbital eccentricities. On the other hand, irregular satellites in the outermost regions of Saturn's moon system, in particular the Norse group, have orbital radii of millions of kilometers and orbital periods lasting several years. The moons of the Norse group also orbit in the opposite direction to Saturn's rotation.
During late July 2009, a moonlet, S/2009 S 1, was discovered in the B Ring, 480 km from the outer edge of the ring, by the shadow it cast. It is estimated to be 300 m in diameter. Unlike the A Ring moonlets (see below), it does not induce a 'propeller' feature, probably due to the density of the B Ring.
In 2006, four tiny moonlets were found in Cassini images of the A Ring. km across—partial gaps in the immediate vicinity of the moonlet itself creating a structure shaped like an airplane propeller. The moonlets themselves are tiny, ranging from about 40 to 500 meters in diameter, and are too small to be seen directly.Before this discovery only two larger moons had been known within gaps in the A Ring: Pan and Daphnis. These are large enough to clear continuous gaps in the ring. In contrast, a moonlet is only massive enough to clear two small—about 10
In 2007, the discovery of 150 more moonlets revealed that they (with the exception of two that have been seen outside the Encke gap) are confined to three narrow bands in the A Ring between 126,750 and 132,000 km from Saturn's center. Each band is about a thousand kilometers wide, which is less than 1% the width of Saturn's rings. This region is relatively free from the disturbances caused by resonances with larger satellites, although other areas of the A Ring without disturbances are apparently free of moonlets. The moonlets were probably formed from the breakup of a larger satellite. It is estimated that the A Ring contains 7,000–8,000 propellers larger than 0.8 km in size and millions larger than 0.25 km. In April 2014, NASA scientists reported the possible consolidation of a new moon within the A Ring, implying that Saturn's present moons may have formed in a similar process in the past when Saturn's ring system was much more massive.
Similar moonlets may reside in the F Ring. km in diameter, orbiting near the F Ring core.There, "jets" of material may be due to collisions, initiated by perturbations from the nearby small moon Prometheus, of these moonlets with the core of the F Ring. One of the largest F Ring moonlets may be the as-yet unconfirmed object S/2004 S 6. The F Ring also contains transient "fans" which are thought to result from even smaller moonlets, about 1
One of the recently discovered moons, Aegaeon, resides within the bright arc of G Ring and is trapped in the 7:6 mean-motion resonance with Mimas.This means that it makes exactly seven revolutions around Saturn while Mimas makes exactly six. The moon is the largest among the population of bodies that are sources of dust in this ring.
Shepherd satellites are small moons that orbit within, or just beyond, a planet's ring system. They have the effect of sculpting the rings: giving them sharp edges, and creating gaps between them. Saturn's shepherd moons are Pan (Encke gap), Daphnis (Keeler gap), Atlas (A Ring), Prometheus (F Ring) and Pandora (F Ring).These moons together with co-orbitals (see below) probably formed as a result of accretion of the friable ring material on preexisting denser cores. The cores with sizes from one-third to one-half the present-day moons may be themselves collisional shards formed when a parental satellite of the rings disintegrated.
Janus and Epimetheus are called co-orbital moons.They are of roughly equal size, with Janus being slightly larger than Epimetheus. Janus and Epimetheus have orbits with only a few kilometers difference in semi-major axis, close enough that they would collide if they attempted to pass each other. Instead of colliding, their gravitational interaction causes them to swap orbits every four years.
The innermost large moons of Saturn orbit within its tenuous E Ring, along with three smaller moons of the Alkyonides group.
Three small moons orbit between Mimas and Enceladus: Methone, Anthe, and Pallene. Named after the Alkyonides of Greek mythology, they are some of the smallest moons in the Saturn system. Anthe and Methone have very faint ring arcs along their orbits, whereas Pallene has a faint complete ring.Of these three moons, only Methone has been photographed at close range, showing it to be egg-shaped with very few or no craters.
Trojan moons are a unique feature only known from the Saturnian system. A trojan body orbits at either the leading L4 or trailing L5 Lagrange point of a much larger object, such as a large moon or planet. Tethys has two trojan moons, Telesto (leading) and Calypso (trailing), and Dione also has two, Helene (leading) and Polydeuces (trailing).Helene is by far the largest trojan moon, while Polydeuces is the smallest and has the most chaotic orbit. These moons are coated with dusty material that has smoothed out their surfaces.
These moons all orbit beyond the E Ring. They are:
Irregular moons are small satellites with large-radii, inclined, and frequently retrograde orbits, believed to have been acquired by the parent planet through a capture process. They often occur as collisional families or groups.The precise size as well as albedo of the irregular moons are not known for sure because the moons are very small to be resolved by a telescope, although the latter is usually assumed to be quite low—around 6% (albedo of Phoebe) or less. The irregulars generally have featureless visible and near infrared spectra dominated by water absorption bands. They are neutral or moderately red in color—similar to C-type, P-type, or D-type asteroids, though they are much less red than Kuiper belt objects.
The Inuit group includes eight prograde outer moons that are similar enough in their distances from the planet (186–297 radii of Saturn), their orbital inclinations (45–50°) and their colors that they can be considered a group. km.The moons are Ijiraq, Kiviuq, Paaliaq, Siarnaq, and Tarqeq, along with three unnamed moons Saturn LX, S/2004 S 31, and S/2019 S 1. The largest among them is Siarnaq with an estimated size of about 40
The Gallic group are four prograde outer moons that are similar enough in their distance from the planet (207–302 radii of Saturn), their orbital inclination (35–40°) and their color that they can be considered a group. km. There is an additional satellite S/2004 S 24 that could belong to this group, but more observations are needed to confirm or disprove its categorization. S/2004 S 24 has the most distant prograde orbit of Saturn's known satellites.They are Albiorix, Bebhionn, Erriapus, and Tarvos. The largest among these moons is Albiorix with an estimated size of about 32
The Norse (or Phoebe) group consists of 46 retrograde outer moons. km. The Norse group may itself consist of several smaller subgroups.They are Aegir, Bergelmir, Bestla, Farbauti, Fenrir, Fornjot, Greip, Hati, Hyrrokkin, Jarnsaxa, Kari, Loge, Mundilfari, Narvi, Phoebe, Skathi, Skoll, Surtur, Suttungr, Thrymr, Ymir, and twenty-five unnamed satellites. After Phoebe, Ymir is the largest of the known retrograde irregular moons, with an estimated diameter of only 18
The Saturnian moons are listed here by orbital period (or semi-major axis), from shortest to longest. Moons massive enough for their surfaces to have collapsed into a spheroid are highlighted in bold and marked with a blue background, while the irregular moons are listed in red, orange and gray background. The orbits and mean distances of the irregular moons are strongly variable over short timescales due to frequent planetary and solar perturbations;therefore, the orbit epochs of all irregular moons are based on the same Julian date of 2459200.5, or 17 December 2020.
Small inner moons
Other round moons
| Diameter |
| Mass |
|Orbital period (d)|| Inclination |
|1||S/2009 S 1||—||≈ 20?||≈ 0.3||< 0.0001||≈ 117000||≈ 0.47000||≈ 0.000||≈ 0.0000||outer B Ring||2009||Cassini|
|(moonlets)||—||—||0.04 to 0.4||< 0.0001||≈ 130000||≈ 0.55000||≈ 0.000||≈ 0.0000||Three 1000 km bands within A Ring||2006||Cassini|
(34 × 31 × 20)
|4.95||133584||+0.57505||≈ 0.000||≈ 0.0000||in Encke Division||1990||Showalter|
(8.6 × 8.2 × 6.4)
|0.084||136505||+0.59408||0.004||≈ 0.0000||in Keeler Gap||2005||Cassini|
(41 × 35 × 19)
|6.6||137670||+0.60169||0.003||0.0012||outer A Ring shepherd||1980||Voyager 1|
(136 × 79 × 59)
|159.5||139380||+0.61299||0.008||0.0022||inner F Ring shepherd||1980||Voyager 1|
(104 × 81 × 64)
|137.1||141720||+0.62850||0.050||0.0042||outer F Ring shepherd||1980||Voyager 1|
(130 × 114 × 106)
|526.6||151422||+0.69433||0.335||0.0098||co-orbital with Janus||1977||Fountain & Larson|
(203 × 185 × 153)
|1897.5||151472||+0.69466||0.165||0.0068||co-orbital with Epimetheus||1966||Dollfus|
(1.4 × 0.5 × 0.4)
|≈ 0.0001||167500||+0.80812||0.001||0.0004||G Ring moonlet||2008||Cassini|
|10||I||† Mimas||/ /||2.7||396.4|
(416 × 393 × 381)
|11||XXXII||Methone||/ /||13.8||2.9||≈ 0.02||194440||+1.00957||0.007||0.0001||Alkyonides||2004||Cassini|
|12||XLIX||Anthe||/ /||14.8||1.8||≈ 0.0015||197700||+1.05089||0.100||0.0011||Alkyonides||2007||Cassini|
(5.8 × 4.2 × 3.7)
|14||II||† Enceladus||/ /||1.8||504.2|
(513 × 503 × 497)
|108022||237950||+1.37022||0.010||0.0047||Generates the E ring||1789||Herschel|
|15||III||† Tethys||/ /||0.3||1062.2|
(1077 × 1057 × 1053)
(33 × 24 × 20)
|≈ 9.41||294619||+1.88780||1.158||0.0000||leading Tethys trojan (L4)||1980||Smith et al.|
(30 × 23 × 14)
|≈ 6.3||294619||+1.88780||1.473||0.0000||trailing Tethys trojan (L5)||1980||Pascu et al.|
|18||IV||† Dione||/ /||0.4||1122.8|
(1128 × 1123 × 1119)
(43 × 38 × 26)
|≈ 24.5||377396||+2.73692||0.199||0.0022||leading Dione trojan (L4)||1980||Laques & Lecacheux|
(3 × 2 × 1)
|≈ 0.03||377396||+2.73692||0.177||0.0192||trailing Dione trojan (L5)||2004||Cassini|
|21||V||† Rhea||/ /||−0.2||1527.6|
(1530 × 1526 × 1525)
|22||VI||♠ Titan||/ /||−1.3||5149.46|
(5149 × 5149 × 5150)
(360 × 266 × 205)
|5619.9||1481010||+21.2766||0.568||0.1230||in 4:3 resonance with Titan||1848||Bond & Lassell|
|24||VIII||† Iapetus||/ /||1.7||1468.6|
(1491 × 1491 × 1424)
|25||‡ S/2019 S 1||—||15.3||≈ 6||≈ 0.15||11221100||+443.78||44.379||0.6229||Inuit group||2021 (2019)||Gladman et al.|
|26||XXIV||‡Kiviuq||/ /||12.7||≈ 17||≈ 2.79||11307500||+448.91||48.930||0.1521||Inuit group||2000||Gladman et al.|
|27||XXII||‡Ijiraq||/ /||13.2||≈ 13||≈ 1.18||11348500||+451.36||49.510||0.3758||Inuit group||2000||Gladman et al.|
(219 × 217 × 204)
|29||XX||‡Paaliaq||/ /||11.9||≈ 25||≈ 7.25||15012800||+686.75||43.688||0.4826||Inuit group||2000||Gladman et al.|
|30||XXVII||♣Skathi||/ /||14.3||≈ 8||≈ 0.35||15563600||−724.90||149.749||0.2755||Norse (Skathi) Group||2000||Gladman et al.|
|31||♣ S/2004 S 37||—||15.9||≈ 4||≈ 0.05||15822400||−743.06||163.046||0.5265||Norse group||2019 (2004)||Sheppard et al.|
|32||♣ S/2007 S 2||—||15.7||≈ 6||≈ 0.15||15971500||−753.58||176.676||0.2465||Norse group||2007||Sheppard et al.|
|33||XXVI||♦Albiorix||/ /||11.1||28.6||≈ 22.3||16222700||+771.43||34.559||0.5807||Gallic group||2000||Holman|
|34||XXXVII||♦Bebhionn||/ /||15.0||≈ 6||≈ 0.15||16900900||+820.31||40.124||0.3813||Gallic group||2004||Sheppard et al.|
|35||LX||‡ S/2004 S 29||—||15.8||≈ 4||≈ 0.05||17202800||+842.39||46.200||0.4269||Inuit group||2019 (2004)||Sheppard et al.|
|36||XLVII||♣Skoll||/ /||15.4||≈ 5||≈ 0.15||17438300||−859.75||157.143||0.4402||Norse group||2006||Sheppard et al.|
|37||‡ S/2004 S 31||—||15.6||≈ 4||≈ 0.05||17449700||+860.58||47.782||0.2525||Inuit group||2019 (2004)||Sheppard et al.|
|38||XXVIII||♦Erriapus||/ /||13.7||≈ 10||≈ 0.68||17705500||+879.58||41.720||0.4520||Gallic group||2000||Gladman et al.|
|39||LII||‡Tarqeq||/ /||14.8||≈ 7||≈ 0.23||17724200||+880.97||50.159||0.1373||Inuit group||2007||Sheppard et al.|
|40||XXIX||‡Siarnaq||/ /||10.6||39.3||≈ 43.5||17937000||+883.87||43.799||0.5293||Inuit group||2000||Gladman et al.|
|41||XXI||♦Tarvos||/ /||12.8||≈ 15||≈ 2.3||18243800||+920.00||37.818||0.4799||Gallic group||2000||Gladman et al.|
|42||XLIV||♣Hyrrokkin||/ /||14.3||≈ 8||≈ 0.35||18348800||−927.95||153.539||0.3582||Norse group||2004||Sheppard et al.|
|43||LI||♣Greip||/ /||15.4||≈ 5||≈ 0.15||18379000||−930.24||172.880||0.3331||Norse group||2006||Sheppard et al.|
|44||XXV||♣Mundilfari||/ /||14.5||≈ 7||≈ 0.23||18470800||−937.22||169.663||0.1787||Norse group||2000||Gladman et al.|
|45||(lost)||♣ S/2004 S 13||—||15.6||≈ 6||≈ 0.15||18594700|
|Norse group||2004||Sheppard et al.|
|46||♣ S/2006 S 1||—||15.6||≈ 5||≈ 0.15||18839700||−965.44||154.904||0.0972||Norse group||2006||Sheppard et al.|
|47||(lost)||♣ S/2007 S 3||—||15.7||≈ 5||≈ 0.09||19143500|
|Norse group||2007||Sheppard et al.|
|48||XXIII||♣Suttungr||/ /||14.5||≈ 7||≈ 0.23||19166800||−990.69||174.091||0.1445||Norse group||2000||Gladman et al.|
|49||LIV||♣ S/2004 S 20||—||15.8||≈ 4||≈ 0.05||19188100||−992.34||162.782||0.1976||Norse group||2019 (2004)||Sheppard et al.|
|50||L||♣Jarnsaxa||/ /||15.6||≈ 6||≈ 0.15||19197900||−993.11||163.780||0.2148||Norse group||2006||Sheppard et al.|
|51||XXXI||♣Narvi||/ /||14.4||≈ 7||≈ 0.23||19226600||−995.33||136.803||0.2990||Norse group||2003||Sheppard et al.|
|52||XXXVIII||♣Bergelmir||/ /||15.2||≈ 5||≈ 0.15||19290200||−1000.28||156.919||0.1399||Norse group||2004||Sheppard et al.|
|53||XLIII||♣Hati||/ /||15.3||≈ 5||≈ 0.15||19435300||−1011.59||164.000||0.3295||Norse group||2004||Sheppard et al.|
|54||(lost)||♣ S/2004 S 17||—||16.0||≈ 4||≈ 0.05||19574300|
|Norse group||2004||Sheppard et al.|
|55||♣ S/2004 S 12||—||15.7||≈ 5||≈ 0.09||19736400|
|Norse group||2004||Sheppard et al.|
|56||LIX||♣ S/2004 S 27||—||15.3||≈ 6||≈ 0.15||19982800||−1054.63||167.707||0.1364||Norse group||2019 (2004)||Sheppard et al.|
|57||XL||♣Farbauti||/ /||15.7||≈ 5||≈ 0.09||20101600||−1064.04||157.484||0.1756||Norse group||2004||Sheppard et al.|
|58||XXX||♣Thrymr||/ /||14.3||≈ 8||≈ 0.23||20236700||−1074.79||174.177||0.4332||Norse group||2000||Gladman et al.|
|59||XXXIX||♣Bestla||/ /||14.6||≈ 7||≈ 0.23||20432100||−1090.39||143.955||0.7072||Norse (Skathi) group||2004||Sheppard et al.|
|60||(lost)||♣ S/2004 S 7||—||15.2||≈ 6||≈ 0.15||20576700|
|Norse group||2004||Sheppard et al.|
|61||XXXVI||♣Aegir||/ /||15.5||≈ 6||≈ 0.15||20598900||−1103.78||166.671||0.2379||Norse group||2004||Sheppard et al.|
|62||LXI||♣ S/2004 S 30||—||16.1||≈ 3||≈ 0.03||20733300||−1114.59||157.121||0.0859||Norse group||2019 (2004)||Sheppard et al.|
|63||LV||♣ S/2004 S 22||—||16.1||≈ 3||≈ 0.03||20737100||−1114.90||177.285||0.2369||Norse group||2019 (2004)||Sheppard et al.|
|64||LVII||♣ S/2004 S 25||—||15.9||≈ 4||≈ 0.05||20814800||−1121.17||172.938||0.4362||Norse group||2019 (2004)||Sheppard et al.|
|65||LXII||♣ S/2004 S 32||—||15.6||≈ 4||≈ 0.05||20963400||−1133.20||159.261||0.2594||Norse group||2019 (2004)||Sheppard et al.|
|66||LVI||♣ S/2004 S 23||—||15.6||≈ 4||≈ 0.05||21444300||−1172.42||176.854||0.4133||Norse group||2019 (2004)||Sheppard et al.|
|67||♣ S/2006 S 3||—||15.6||≈ 6||≈ 0.15||21607300||−1185.81||152.958||0.4533||Norse group||2006||Sheppard et al.|
|68||LXV||♣ S/2004 S 35||—||15.5||≈ 6||≈ 0.15||21864500||−1207.04||176.771||0.2030||Norse group||2019 (2004)||Sheppard et al.|
|69||XLV||♣Kari||/ /||14.8||≈ 6||≈ 0.23||21988000||−1217.28||149.188||0.3745||Norse (Skathi) group||2006||Sheppard et al.|
|70||♣ S/2004 S 28||—||15.8||≈ 4||≈ 0.05||22134400||−1229.46||170.617||0.1249||Norse group||2019 (2004)||Sheppard et al.|
|71||XLVI||♣Loge||/ /||15.3||≈ 5||≈ 0.15||22563800||−1265.42||166.811||0.1584||Norse group||2006||Sheppard et al.|
|72||LXVI||♣ S/2004 S 38||—||15.9||≈ 4||≈ 0.05||22616000||−1269.81||154.654||0.4084||Norse group||2019 (2004)||Sheppard et al.|
|73||XLI||♣Fenrir||/ /||15.9||≈ 4||≈ 0.05||22753400||−1281.39||162.874||0.0949||Norse group||2004||Sheppard et al.|
|74||XIX||♣Ymir||/ /||12.3||≈ 19||≈ 3.97||22841900||−1288.88||172.157||0.3431||Norse group||2000||Gladman et al.|
|75||XLVIII||♣Surtur||/ /||15.8||≈ 6||≈ 0.15||23065900||−1307.89||166.008||0.3591||Norse group||2006||Sheppard et al.|
|76||LXIII||♣ S/2004 S 33||—||15.9||≈ 4||≈ 0.05||23087600||−1309.73||159.866||0.4113||Norse group||2019 (2004)||Sheppard et al.|
|77||♦ S/2004 S 24||—||16.0||≈ 3||≈ 0.03||23326300||+1330.10||36.240||0.0400||Gallic group?||2019 (2004)||Sheppard et al.|
|78||♣ S/2004 S 21||—||16.3||≈ 3||≈ 0.03||23356200||−1332.66||156.200||0.3156||Norse group||2019 (2004)||Sheppard et al.|
|79||♣ S/2004 S 39||—||16.3||≈ 3||≈ 0.03||23463800||−1341.87||166.578||0.0979||Norse group||2019 (2004)||Sheppard et al.|
|80||♣ S/2004 S 36||—||16.1||≈ 3||≈ 0.03||23576500||−1351.56||155.188||0.7139||Norse group||2019 (2004)||Sheppard et al.|
|81||XLII||♣Fornjot||/ /||14.9||≈ 6||≈ 0.15||24451700||−1427.51||167.847||0.1613||Norse group||2004||Sheppard et al.|
|82||LXIV||♣ S/2004 S 34||—||16.1||≈ 3||≈ 0.03||24865000||−1463.85||166.039||0.2015||Norse group||2019 (2004)||Sheppard et al.|
|83||LVIII||♣ S/2004 S 26||—||15.8||≈ 4||≈ 0.05||26701600||−1628.99||171.575||0.1726||Norse group||2019 (2004)||Sheppard et al.|
The following objects (observed by Cassini ) have not been confirmed as solid bodies. It is not yet clear if these are real satellites or merely persistent clumps within the F Ring.
|S/2004 S 3 and S 4||≈ 3–5||≈ 140300||≈ +0.619||uncertain objects around the F Ring||2004||Were undetected in thorough imaging of the region in November 2004, making their existence improbable|
|S/2004 S 6||≈ 3–5||≈ 140130||+0.61801||2004||Consistently detected into 2005, may be surrounded by fine dust and have a very small physical core|
Two moons were claimed to be discovered by different astronomers but never seen again. Both moons were said to orbit between Titan and Hyperion.
Much like Jupiter, asteroids and comets will infrequently make close approaches to Saturn, even more infrequently becoming captured into orbit of the planet. The comet P/2020 F1 (Leonard) is calculated to have made a close approach of 978000±65000 km (608000±40000 mi to Saturn on 8 May 1936, closer than the orbit of Titan to the planet, with an orbital eccentricity of only 1.098±0.007. The comet may have been orbiting Saturn prior to this as a temporary satellite, but difficulty modelling the non-gravitational forces makes whether or not it was indeed a temporary satellite uncertain.
Other comets and asteroids may have temporarily orbited Saturn at some point, but none are presently known to have.
It is thought that the Saturnian system of Titan, mid-sized moons, and rings developed from a set-up closer to the Galilean moons of Jupiter, though the details are unclear. It has been proposed either that a second Titan-sized moon broke up, producing the rings and inner mid-sized moons,or that two large moons fused to form Titan, with the collision scattering icy debris that formed the mid-sized moons. On June 23, 2014, NASA claimed to have strong evidence that nitrogen in the atmosphere of Titan came from materials in the Oort cloud, associated with comets, and not from the materials that formed Saturn in earlier times. Studies based on Enceladus's tidal-based geologic activity and the lack of evidence of extensive past resonances in Tethys, Dione, and Rhea's orbits suggest that the moons inward of Titan may be only 100 million years old.
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 nine and a half times that of Earth. It only has one-eighth the average density of Earth; however, with its larger volume, Saturn is over 95 times more massive. Saturn is named after the Roman god of wealth and agriculture. Its astronomical symbol (♄) has been traced back to the Greek Oxyrhynchus Papyri, where it can be seen to be a Greek kappa-rho with a cross-bar, as an abbreviation for Κρονος (Cronos), the Greek name for the planet. It later came to look like a lower-case Greek eta, with the cross added at the top in the 16th century.
A natural satellite is in the most common usage, an astronomical body that orbits a planet, dwarf planet, or small solar system body. While natural satellites are often colloquially referred to as moons, there is only the Moon of Earth.
Rhea is the second-largest moon of Saturn and the ninth-largest moon in the Solar System. It is the smallest body in the Solar System for which precise measurements have confirmed a shape consistent with hydrostatic equilibrium. It was discovered in 1672 by Giovanni Domenico Cassini.
The Cassini–Huygens space-research mission, commonly called Cassini, involved a collaboration among NASA, the European Space Agency (ESA), and the Italian Space Agency (ASI) to send a space probe to study the planet Saturn and its system, including its rings and natural satellites. The Flagship-class robotic spacecraft comprised both NASA's Cassini space probe and ESA's Huygens lander, which landed on Saturn's largest moon, Titan. Cassini was the fourth space probe to visit Saturn and the first to enter its orbit. The two craft took their names from the astronomers Giovanni Cassini and Christiaan Huygens.
Tethys, or Saturn III, is a mid-sized moon of Saturn about 1,060 km (660 mi) across. It was discovered by G. D. Cassini in 1684 and is named after the titan Tethys of Greek mythology.
Iapetus is the third-largest natural satellite of Saturn and the eleventh-largest in the Solar System. Discoveries by the Cassini mission in 2007 revealed several unusual features, such as a massive equatorial ridge running three-quarters of the way around the moon and a distinctive color pattern.
Hyperion, also known as Saturn VII (7), is a moon of Saturn discovered by William Cranch Bond, his son George Phillips Bond and William Lassell in 1848. It is distinguished by its irregular shape, its chaotic rotation, and its unexplained sponge-like appearance. It was the first non-round moon to be discovered.
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 is a moon of Saturn. It was discovered by Italian astronomer Giovanni Domenico Cassini in 1684. It is named after the Titaness Dione of Greek mythology. It is also designated Saturn IV.
Enceladus is the sixth-largest moon of Saturn. It is about 500 kilometers (310 mi) in diameter, about a tenth of that of Saturn's largest moon, Titan. Enceladus is mostly covered by fresh, clean ice, making it one of the most reflective bodies of the Solar System. Consequently, its surface temperature at noon only reaches −198 °C (−324 °F), far colder than a light-absorbing body would be. Despite its small size, Enceladus has a wide range of surface features, ranging from old, heavily cratered regions to young, tectonically deformed terrains.
Mimas, also designated Saturn I, is a moon of Saturn which was discovered in 1789 by William Herschel. It is named after Mimas, a son of Gaia in Greek mythology.
Phoebe is an irregular satellite of Saturn with a mean diameter of 213 km (132 mi). It was discovered by William Henry Pickering on March 18, 1899 from photographic plates that had been taken starting on 16 August 1898 at the Boyden Station of the Carmen Alto Observatory near Arequipa, Peru, by DeLisle Stewart. It was the first satellite to be discovered photographically.
Methone is a small, egg-shaped moon 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.
The rings of Saturn are the most extensive ring system of any planet in the Solar System. They consist of countless small particles, ranging in size from micrometers to meters, that orbit around Saturn. The ring particles are made almost entirely of water ice, with a trace component of rocky material. There is still no consensus as to their mechanism of formation. Although theoretical models indicated that the rings were likely to have formed early in the Solar System's history, newer data from Cassini suggested they formed relatively late.
Polydeuces, or Saturn XXXIV, is a small natural satellite of Saturn that is co-orbital with the moon Dione and librates around its trailing Lagrangian point (L5). Its diameter is estimated to be 2–3 km. Dione's other co-orbital moon is Helene, which is bigger and located at the leading L4 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 kilometres in diameter, and orbits the planet in the Keeler Gap within the A ring.
The tiger stripes of Enceladus consist of four sub-parallel, linear depressions in the south polar region of the Saturnian moon. First observed on May 20, 2005 by the Cassini spacecraft's Imaging Science Sub-system (ISS) camera, the features are most notable in lower resolution images by their brightness contrast from the surrounding terrain. Higher resolution observations were obtained by Cassini's various instruments during a close flyby of Enceladus on July 14, 2005. These observations revealed the tiger stripes to be low ridges with a central fracture. Observations from the Composite Infrared Spectrometer (CIRS) instrument showed the tiger stripes to have elevated surface temperatures, indicative of present-day cryovolcanism on Enceladus centered on the tiger stripes.
Several of Saturn's natural satellites have figured prominently in works of science fiction.
A planetary-mass moon is a planetary-mass object that is also a natural satellite. They are large and ellipsoidal in shape. Two moons in the Solar System are larger than the planet Mercury : Ganymede and Titan, and seven are larger and more massive than the dwarf planet Pluto.
The following outline is provided as an overview of and topical guide to Saturn:
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