The full set of rings, photographed as Saturn eclipsed the sun from the vantage of the Cassini spacecraft on September 15, 2006 (brightness has been exaggerated in this image).

In this image of Saturn taken by the Hubble Space Telescope's ACS on March 22, 2004, the B Ring is the inner of the two wide rings, the A Ring is the outer, and the Cassini Division is the dark band between them. (The less prominent C Ring is also visible just inside the B Ring.)

The unilluminated side of Saturn's rings viewed from Cassini on May 9, 2007

The rings of Saturn are a system of planetary rings around the planet Saturn. They consist of countless small particles, ranging in size from microns to meters, that form clumps that in turn orbit about Saturn. The ring particles are made almost entirely of water ice, with some contamination from dust and other chemicals. Image File history File links Size of this preview: 800 × 395 pixelsFull resolution (2766 × 1364 pixel, file size: 596 KB, MIME type: image/jpeg) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File links Size of this preview: 800 × 395 pixelsFull resolution (2766 × 1364 pixel, file size: 596 KB, MIME type: image/jpeg) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Cassini-Huygens is a joint NASA/ESA/ASI unmanned space mission intended to study Saturn and its moons. ... is the 258th day of the year (259th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... The Hubble Space Telescope (HST) is a telescope in orbit around the Earth, named after astronomer Edwin Hubble. ... Introduction The Advanced Camera for Surveys (ACS) is a third generation axial instrument aboard the Hubble Space Telescope (HST). ... is the 81st day of the year (82nd in leap years) in the Gregorian calendar. ... Year 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... A planetary ring is a ring of dust and other small particles orbiting around a planet in a flat disc-shaped region. ... Atmospheric characteristics Atmospheric pressure 140 kPa Hydrogen >93% Helium >5% Methane 0. ... A micrometre (American spelling: micrometer, symbol µm) is an SI unit of length equal to one millionth of a metre, or about a tenth of the diameter of a droplet of mist or fog. ... This article is about the unit of length. ... Two bodies with a slight difference in mass orbiting around a common barycenter. ... This article is about water ice. ... Look up dust in Wiktionary, the free dictionary. ...

Although reflection from the rings increases Saturn's brightness, they are not visible from Earth with unaided vision. In 1610, the year he first turned a telescope to the sky, Galileo Galilei became the very first person to observe Saturn's rings, though he could not see them well enough to discern their true nature. In 1655, Christiaan Huygens was the first person to describe them as a disk surrounding Saturn.^[1] The apparent magnitude (m) of a star, planet or other celestial body is a measure of its apparent brightness as seen by an observer on Earth. ... The naked eye is a figure of speech referring to human visual perception that is unaided by enhancing equipment, such as a telescope or binoculars. ... // Events January 7 - Galileo Galilei discovers the Galilean moons of Jupiter. ... This article does not cite any references or sources. ... Galileo redirects here. ... Events March 25 - Saturns largest moon, Titan, is discovered by Christian Huygens. ... Christiaan Huygens (pronounced in English (IPA): ; in Dutch: ) (April 14, 1629 – July 8, 1698), was a Dutch mathematician, astronomer and physicist; born in The Hague as the son of Constantijn Huygens. ...

Although many people think of Saturn's rings as being made up of "countless tiny ringlets" (a concept that goes back to Laplace), true gaps are few in number. It is more correct to think of the rings as an annular disk with concentric local maxima and minima in density and brightness. On the scale of the clumps within the rings there is a lot of empty space, but in general these empty spaces are discontinuous. Pierre-Simon, marquis de Laplace (March 23, 1749 - March 5, 1827) was a French mathematician and astronomer whose work was pivotal to the development of mathematical astronomy. ... An annulus In mathematics, an annulus (the Latin word for little ring, with plural annuli) is a ring-shaped geometric figure, or more generally, a term used to name a ring-shaped object. ... Concentric objects share the same center, axis or origin with one inside the other. ... Local and global maxima and minima for cos(3Ï€x)/x, 0. ...

There are several gaps within the rings: two opened by known moons embedded within them, and many others at locations of known destabilizing orbital resonances with Saturn's moons. Other gaps remain unexplained. Stabilizing resonances, on the other hand, are responsible for the longevity of several rings, such as the Titan Ringlet and the G Ring. In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other. ... The Saturnian system (photographic montage) Saturn has 60 confirmed natural satellites, plus three hypothetical moons. ...

Formation of Saturn's rings

A 2007 artist impression of the aggregates of icy particles that form the 'solid' portions of Saturn's rings. These elongated clumps are continually forming and dispersing. The largest particles are a few meters across.

Saturn's rings may be very old, dating to the formation of Saturn itself. It seems likely that they are composed of debris from the disruption of a moon about 300 km in diameter, bigger than Mimas. The last time there were collisions large enough to be likely to disrupt a moon that large was during the Late Heavy Bombardment some four billion years ago.^[2] Mimas (mee-məs or mye-məs, IPA: , Greek Μίμᾱς, rarely Μίμανς) is a moon of Saturn that was discovered in 1789 by William Herschel. ... The Late Heavy Bombardment (LHB) was a period approximately 3. ...

The brightness and purity of the water ice in Saturn's rings has been cited as evidence that the rings are much younger than Saturn, perhaps 100 million years old, as the infall of meteoric dust would have led to darkening of the rings. However, new research indicates that the B Ring may be massive enough to have diluted infalling material and thus avoided substantial darkening over the age of the Solar system. Ring material may be recycled as clumps form within the rings and are then disrupted by impacts. This would explain the apparent youth of some of the material within the rings.^[3]

The Cassini UVIS team, led by Larry Esposito, used stellar occultation to discover 13 objects, ranging from 27 meters to 10 km across, within the F ring. They are translucent, suggesting they are temporary aggregates of ice boulders a few meters across. Esposito believes this to be the basic structure of the Saturnian rings, particles clumping together, then being blasted apart. Larry W. Esposito is a Professor at the Laboratory for Atmospheric and Space Physics, University of Colorado. ... In this July, 1997 still frame captured from video, the bright star Aldebaran has just reappeared on the dark limb of the waning crescent moon in this predawn occultation. ... Close up view of Prometheus and the F Ring Categories: Astronomy stubs | Saturn ...

Subdivisions and structures within the rings

The densest parts of the Saturnian ring system are the A and B Rings, which are separated by the Cassini Division (discovered in 1675 by Giovanni Domenico Cassini). Along with the C Ring, which was discovered in 1850 and is similar in character to the Cassini Division, these regions comprise the Main Rings. The Main Rings are denser and contain larger particles than the tenuous Dusty Rings. The latter include the D Ring, extending inward to Saturn's cloud tops, the G and E Rings and others beyond the main ring system. The word "dusty" used to characterize these diffuse rings refers to the small size of the particles (often about a micron); their chemical composition is, like the main rings, almost entirely of water ice. The narrow F Ring, just off the outer edge of the A Ring, is more difficult to categorize; parts of it are very dense, but it also contains a great deal of dust-size particles. Year 1675 (MDCLXXV) was a common year starting on Tuesday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Friday of the 10-day slower Julian calendar). ... Giovanni Domenico (Jean-Dominique) Cassini Portrait Giovanni Domenico Cassini (June 8, 1625–September 14, 1712) was an Italian astronomer, engineer, and astrologer. ... For the game, see: 1850 (board game) 1850 (MDCCCL) was a common year starting on Tuesday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Sunday [1] of the 12-day-slower Julian calendar). ... A micrometre (American spelling: micrometer, symbol µm) is an SI unit of length equal to one millionth of a metre, or about a tenth of the diameter of a droplet of mist or fog. ... This article is about water ice. ...

Natural-color mosaic of Cassini narrow-angle camera images of the unilluminated side of Saturn's D, C, B, A and F rings (left to right) taken on May 9, 2007.

The illuminated side of Saturn's rings with the major subdivisions labelled

Image File history File links Size of this preview: 800 × 97 pixelsFull resolution (11795 × 1425 pixel, file size: 1. ... Cassini-Huygens is a joint NASA/ESA/ASI unmanned space mission intended to study Saturn and its moons. ... is the 129th day of the year (130th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... Image File history File links Download high resolution version (994x1000, 146 KB)The rings of Saturn, with the major rings labelled File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File links Download high resolution version (994x1000, 146 KB)The rings of Saturn, with the major rings labelled File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...

Major subdivisions of the rings

Giovanni Domenico (Jean-Dominique) Cassini Portrait Giovanni Domenico Cassini (June 8, 1625–September 14, 1712) was an Italian astronomer, engineer, and astrologer. ... Édouard Albert Roche (1820-1883) was a French scientist. ... Janus (jay-nus, IPA: , Greek Ιανός) is an inner satellite of Saturn. ... Epimetheus (ep-i-mee-thee-us, Greek Επιμηθεύς) is a moon of Saturn. ... Discovery image of Pallene Pallene (pa-lee-nee, Greek Παλλήνη) is a natural satellite of Saturn. ...

Structures within the C Ring

Giuseppe Colombo (October 2, 1920 â€“ February 20, 1984), better known by his nickname Bepi Colombo, was an Italian scientist, mathematician and engineer at the University of Padua, Italy. ... Titan (, from Ancient Greek Τῑτάν) or Saturn VI is the largest moon of Saturn and the only moon known to have a dense atmosphere. ... James Clerk Maxwell (13 June 1831 – 5 November 1879) was a Scottish mathematician and theoretical physicist. ...

Structures within the Cassini Division

Christiaan Huygens (pronounced in English (IPA): ; in Dutch: ) (April 14, 1629 – July 8, 1698), was a Dutch mathematician, astronomer and physicist; born in The Hague as the son of Constantijn Huygens. ...

Structures within the A Ring

Notes:
⁽¹⁾ distance is to centre of gaps, rings and ringlets that are narrower than 1000 km
⁽²⁾ unofficial name
⁽³⁾ Names as designated by the International Astronomical Union, unless otherwise noted.
⁽⁴⁾ Data mostly from the Gazetteer of Planetary Nomenclature and this NASA factsheet.
Johann Franz Encke (23 September 1791 – 26 August 1865) was a German astronomer, born in Hamburg. ... James Edward Keeler (September 10, 1857 – August 12, 1900) was an American astronomer. ... IAU redirects here. ...

Oblique (4 degree angle) Cassini images of Saturn's C, B, and A rings (left to right; the F ring is faintly visible in the full size upper image if viewed at sufficient brightness). Upper image: natural color mosaic of Cassini narrow-angle camera photos of the illuminated side of the rings taken on December 12, 2004. Lower image: simulated view constructed from a radio occultation observation conducted on May 3, 2005. Color in the lower image is used to represent information about ring particle sizes.

Image File history File links Size of this preview: 800 × 120 pixelsFull resolution (5776 × 864 pixel, file size: 491 KB, MIME type: image/jpeg) File historyClick on a date/time to view the file as it appeared at that time. ... Cassini-Huygens is a joint NASA/ESA/ASI unmanned space mission intended to study Saturn and its moons. ... is the 346th day of the year (347th in leap years) in the Gregorian calendar. ... Year 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... Radio occultation (RO) is a remote sensing technique used for measuring the physical properties of a planetary atmosphere. ... is the 123rd day of the year (124th in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ...

D Ring

A Cassini image of Saturn's D ring processed to show faint ripples within it; the much brighter C ring appears in the upper left.

The D Ring is the innermost ring, and is very faint. In 1980, Voyager 1 detected within this ring three ringlets designated D73, D72 and D68, with D68 being the discrete ringlet nearest to Saturn. Some 25 years later Cassini images showed that D72 had become significantly fainter and moved planetward by 200 kilometres. Present in the gap between the C ring and D73 is finescale structure with waves 30 kilometres apart. For the album by The Verve, see Voyager 1 (album). ...

C Ring

The Maxwell Gap, with the Maxwell Ringlet on its right side, lies above and right of center in this Cassini image of Saturn's outer C Ring.

The C Ring is a wide but faint ring located inward of the B Ring. It was discovered in 1850 by William and George Bond, though William R. Dawes and Johann Galle also saw it independently. William Lassell termed it the "Crepe Ring" because it seemed to be composed of darker material than the brighter A and B Rings.^[4] William Cranch Bond William Cranch Bond (September 9, 1789 – January 29, 1859) was an American astronomer, and the first director of Harvard College Observatory. ... George Phillips Bond (May 20, 1825 – February 17, 1865) was an American astronomer. ... William Rutter Dawes (March 19, 1799 – February 15, 1868) was a British astronomer. ... Johann Gottfried Galle Johann Gottfried Galle (June 9, 1812 in Radis, Saxony-Anhalt – July 10, 1910 in Potsdam, Brandenburg) was a German astronomer at the Berlin Observatory who, with the assistance of student Heinrich Louis dArrest, was the first person to view the planet Neptune, and know what he... William Lassell (June 18, 1799 – October 5, 1880) was a British astronomer, born in Bolton, Lancashire, England. ...

Its vertical thickness is estimated at 5 metres, its mass at around 1.1 × 10¹⁸ kilograms, and its optical depth varies from 0.05 to 0.12. [1]. That is, 5 and 12 percent of light shining through perpendicular to the ring is blocked, so that when seen from above or below, the ring is close to transparent. Kg redirects here. ... This article does not cite any references or sources. ...

Colombo Gap and Titan Ringlet

The Colombo Gap lies in the inner C Ring. Within the gap lies the bright but narrow Colombo Ringlet, centered at 77,883 kilometers from Saturn's center, which is slightly elliptical rather than circular. This ringlet is also called the Titan Ringlet as it is governed by an orbital resonance with the moon Titan. [2] At this location within the rings, the time period of a ring particle's apsidal precession is equal to the time period of Titan's orbital motion, so that the outer end of this eccentric ringlet always points towards Titan. For other uses, see Ellipse (disambiguation). ... In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other. ... Titan (, from Ancient Greek Τῑτάν) or Saturn VI is the largest moon of Saturn and the only moon known to have a dense atmosphere. ... Precession redirects here. ...

Maxwell Gap

The Maxwell Gap lies within the outer C Ring. It also contains a dense non-circular ringlet, the Maxwell Ringlet.

B Ring

Dark B ring spokes are visible in this Cassini image of the unilluminated side of the rings. Left of center, two dark gaps (the larger being the Huygens Gap) and the bright (from this viewing geometry) ringlets between and immediately beyond them comprise the Cassini Division.

The B Ring is the largest, brightest, and most massive of the rings. Its thickness is estimated as 5 to 10 metres, its mass at 2.8 × 10¹⁹ kg, and its optical depth varies from 0.4 to 2.5, [3] meaning that well over 99% of the light passing through some parts of the B Ring is blocked. The B Ring contains a great deal of variation in its density and brightness, nearly all of it unexplained. These are concentric, appearing in the form of narrow ringlets, though the B Ring does not contain any gaps. This article does not cite any references or sources. ... Concentric objects share the same center, axis or origin with one inside the other. ...

Spokes

During the Voyager encounters, extended short-lived spoke-like features were seen in the B ring under some viewing geometries. Their nature was the focus of lively scientific debate, and several hypotheses were proposed as to their cause and makeup. Spokes were seen by the Hubble Space Telescope in the late 1990s and early 2000s. When the Cassini spacecraft entered into orbit around Saturn, the spokes were mysteriously absent. Suggestions that spokes may be a seasonal effect, varying with Saturn's 29.7-year orbit, were supported by their gradual reappearance in the later years of the Cassini mission. The leading theory is that spokes are made of tiny dust particles suspended above the main ring by electrostatic repulsion. Suggestions for the origin of the electrical disturbances include lighting bolts in Saturn's atmosphere and micrometeoroid impacts on the rings. The spokes appear dark in backscattered light, and bright in forward-scattered light. Voyager Project redirects here. ... The Hubble Space Telescope (HST) is a telescope in orbit around the Earth, named after astronomer Edwin Hubble. ... Cassini-Huygens is a joint NASA/ESA/ASI unmanned space mission intended to study Saturn and its moons. ... This article or section is in need of attention from an expert on the subject. ... A year (from Old English gēr) is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... Electrostatics is the branch of physics that deals with the force exerted by a static (i. ... A Micrometeoroid (also micrometeorite, micrometeor) is a tiny meteoroid; a small particle of rock from space, usually weighing less than a gram, that poses a threat to space exploration. ... Backscatter is the reflection of waves, particles, or signals back to the direction they came from. ... In telecommunication, forward scatter is the deflection--by diffraction, nonhomogeneous refraction, or nonspecular reflection by particulate matter of dimensions that are large with respect to the wavelength in question but small with respect to the beam diameter--of a portion of an incident electromagnetic wave, in such a manner that...

Cassini Division

The Cassini Division is a 4,800 km (2,980 mile) wide region between the A Ring and B Ring. It was discovered in 1675 by Giovanni Cassini. From Earth it appears as a thin black gap in the rings. However, Voyager discovered that the gap is itself populated by ring material bearing much similarity to the C Ring. The division may appear bright in views of the unlit side of the rings, since the relatively low density of material allows more light to be transmitted through the thickness of the rings. Year 1675 (MDCLXXV) was a common year starting on Tuesday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Friday of the 10-day slower Julian calendar). ... Giovanni Domenico (Jean-Dominique) Cassini Portrait Giovanni Domenico Cassini (June 8, 1625–September 14, 1712) was an Italian astronomer, engineer, and astrologer. ... Voyager Project redirects here. ...

The inner edge of the Cassini Division is governed by a strong orbital resonance. Ring particles at this location orbit twice for every orbit of the moon Mimas. The resonance causes Mimas' pulls on these ring particles to accumulate, destabilizing their orbits and leading to a sharp cutoff in ring density. Many of the other gaps between ringlets within the Cassini Division, however, are unexplained. In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other. ... Mimas (mee-məs or mye-məs, IPA: , Greek Μίμᾱς, rarely Μίμανς) is a moon of Saturn that was discovered in 1789 by William Herschel. ...

Huygens Gap

The Huygens Gap is at the inner edge of the Cassini Division. It contains the dense Huygens Ringlet, which is non-circular.

A Ring

The A Ring is the outermost of the large, bright rings. Its inner boundary is the Cassini Division and its sharp outer boundary is close to the orbit of the small moon Atlas. The A Ring is interrupted at a location 22% of the ring width from its outer edge by the Encke Gap. A narrower gap 2% of the ring width from the outer edge is called the Keeler Gap. Atmospheric pressure 0 kPa Atlas (at-lus, Greek Άτλας) is a moon of Saturn. ...

The thickness of the A Ring is estimated as 10 to 30 metres, its mass as 6.2 × 10¹⁸ kg (about the mass of Hyperion), and its optical depth varies from 0.4 to 1.0. [4] Hyperion (IPA: , Greek Ὑπερίων) is a moon of Saturn discovered by William Cranch Bond, George Phillips Bond and William Lassell in 1848. ... This article does not cite any references or sources. ...

Similarly to the B Ring, the A Ring's outer edge is maintained by an orbital resonance, in this case the 7:6 resonance with Janus and Epimetheus. Other orbital resonances also excite many spiral density waves in the A Ring (and, to a lesser extent, other rings as well), which account for most of its structure. These waves are described by the same physics that describes the spiral arms of galaxies. Spiral bending waves, also present in the A Ring and also described by the same theory, are vertical corrugations in the ring rather than compression waves. In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other. ... Janus (jay-nus, IPA: , Greek Ιανός) is an inner satellite of Saturn. ... Epimetheus (ep-i-mee-thee-us, Greek Επιμηθεύς) is a moon of Saturn. ... Density Wave Theory or the Lin-Shu Density Wave Theory is a theory proposed by C.C. Lin and Frank Shu in the mid-1960s to explain spiral arm structure of certain galaxies. ... An example of a spiral galaxy, the Pinwheel Galaxy (also known as Messier 101 or NGC 5457) A spiral galaxy is a galaxy belonging to one of the three main classes of galaxy originally described by Edwin Hubble in his 1936 work “The Realm of the Nebulae”[1] and, as... A light wave is an example of a transverse wave. ... Longitudinal waves are waves that have vibrations along or parallel to their direction of travel. ...

Encke Gap

The Encke Gap, sometimes called the Encke Division, is a gap within the A Ring. Johann Encke himself did not observe this gap; it was named in honour of his ring observations. The gap itself was discovered by James Edward Keeler in 1888. Johann Franz Encke (September 23, 1791 – August 26, 1865) was a German astronomer, born in Hamburg. ... James Edward Keeler (September 10, 1857 – August 12, 1900) was an American astronomer. ... For the toll-free telephone number see Toll-free telephone number Year 1888 (MDCCCLXXXVIII) was a leap year starting on Sunday (click on link for calendar) of the Gregorian calendar (or a leap year starting on Friday of the 12-day slower Julian calendar). ...

The gap is centered at a distance 133,580 kilometers from Saturn's center, and has a width of 325 kilometers. [5] It is caused by the presence of the small moon Pan, which orbits within it. A kilometer (Commonwealth spelling: kilometre), symbol: km is a unit of length in the metric system equal to 1,000 metres (from the Greek words χίλια (khilia) = thousand and μέτρο (metro) = count/measure). ... Atmosphere none Pan (pan, Greek Πάν) is a moon of Saturn, named after the god Pan. ...

Images from the Cassini probe have shown that there are at least three thin, knotted ringlets within the gap. [6] This is an artists concept of Cassini during the Saturn Orbit Insertion (SOI) maneuver, just after the main engine has begun firing. ...

Keeler Gap

The Keeler Gap is a 42-kilometre-wide gap in the A Ring, approximately 250 kilometres from the ring's outer edge. It is named after the astronomer James Edward Keeler. The small moon Daphnis, discovered May 1, 2005, orbits within it, keeping it clear. James Edward Keeler (September 10, 1857 – August 12, 1900) was an American astronomer. ... Atmosphere none Daphnis (IPA: , Greek Δαφνίς) is an inner satellite of Saturn. ... is the 121st day of the year (122nd in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ...

The Encke Gap's central ringlet coincides with Pan’s orbit, implying its particles oscillate in horseshoe orbits. Spiral density waves, which pervade much of the A Ring, are visible on both sides of the gap. Atmosphere none Pan (pan, Greek Πάν) is a moon of Saturn, named after the god Pan. ... A horseshoe orbit is the type of orbit you get when you observe an object from another nearly co-orbital object, such as a planet. ... Density Wave Theory or the Lin-Shu Density Wave Theory is a theory proposed by C.C. Lin and Frank Shu in the mid-1960s to explain spiral arm structure of certain galaxies. ...

The motion of Pan (not visible) through the Encke Gap induces edge waves and a set of spiraling wakes (which are not self-propagating). The other, more tightly wound bands are spiral density waves induced by resonances with inner moons. Atmosphere none Pan (pan, Greek Πάν) is a moon of Saturn, named after the god Pan. ... This article does not cite any references or sources. ... Density Wave Theory or the Lin-Shu Density Wave Theory is a theory proposed by C.C. Lin and Frank Shu in the mid-1960s to explain spiral arm structure of certain galaxies. ... In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other. ... The Saturnian system (photographic montage) Moons of Saturn (photographic montage) Saturn has 60 confirmed natural satellites, plus three hypothetical moons. ...

The passage of Daphnis induces waves in the edges of the Keeler gap. Orbital motion is to the lower left; speed decreases going towards the A Ring edge. Atmosphere none Daphnis (IPA: , Greek Δαφνίς) is an inner satellite of Saturn. ...

Moonlets

In 2006, four tiny "moonlets" were found in Cassini images of the A Ring.^[5] The moonlets themselves are only about a hundred meters in diameter, too small to be seen directly; what Cassini sees are the "propeller"-shaped disturbance the moonlets create, which are several km across. It is estimated that the A Ring contains thousands of such objects. In 2007, the discovery of eight more moonlets revealed that they are largely confined to a 3000-km belt, about 130,000 km from Saturn's center^[6] Over 150 "propeller" moonlets have now been detected.^[7]

Roche Division

The gap between the A Ring and the F Ring has been named the Roche Division in honor of the French physicist Édouard Roche.[7] The Roche Division should not be confused with the Roche limit, a physical concept that describes when a large object gets so close to a planet (such as Saturn) that the planet's tidal forces will pull it apart. Lying at the outer edge of the main ring system, the Roche Division is in fact close to Saturn's Roche limit, which is why the rings have been unable to accrete into a moon. Édouard Albert Roche (1820-1883) was a French scientist. ... The Roche limit, sometimes referred to as the Roche radius, is the distance within which a celestial body held together only by its own gravity will disintegrate due to a second celestial bodys tidal forces exceeding the first bodys gravitational self-attraction. ... Comet Shoemaker-Levy 9 after breaking up under the influence of Jupiters tidal forces. ... In astrophysics, the term accretion is used for at least two distinct processes. ...

Like the Cassini Division, the Roche Division is not empty but contains a sheet of material. The character of this material is similar to the tenuous and dusty D, E, and G Rings. Two locations in the Roche Division have a higher concentration of dust than the rest of the region. These were discovered by the Cassini probe imaging team and were given temporary designations: R/2004 S 1, which lies along the orbit of the moon Atlas; and R/2004 S 2, centered at 138,900 km from Saturn's center, inward of the orbit of Prometheus. This is an artists concept of Cassini during the Saturn Orbit Insertion (SOI) maneuver, just after the main engine has begun firing. ... In ancient times, only the Sun and Moon, a few hundred stars and the most easily visible planets had names. ... Atmospheric pressure 0 kPa Atlas (at-lus, Greek Άτλας) is a moon of Saturn. ... Prometheus (proe-mee-thee-us, Greek Προμηθέας) is a moon of Saturn. ...

F Ring

The F Ring is one of the outer rings of Saturn. It is located outside the larger rings, just 3000 km beyond the outer edge of the A Ring.^[8] It was discovered in 1979 by the Pioneer 11 imaging team.^[9] It is very thin, just a few hundred kilometers wide, and is held together by two shepherd moons, Prometheus and Pandora, which orbit inside and outside it. Position of Pioneer 10 and 11 Pioneer 11 was the second mission to investigate Jupiter and the outer solar system and the first to explore the planet Saturn and its main rings. ... A planetary ring is a ring of dust and other small particles orbiting around a planet in a flat disc-shaped region. ... Prometheus (proe-mee-thee-us, Greek Προμηθέας) is a moon of Saturn. ... Pandora (pan-dor-a, Greek Πανδώρα) is a moon of Saturn. ...

Recent closeup images from the Cassini probe show that the F Ring consists of one core ring and a spiral strand around it. They also show that when Prometheus encounters the ring at its apoapsis, its gravitational attraction creates kinks and knots in the F Ring as the moon 'steals' material from it, leaving a dark channel in the inner part of the ring. Since Prometheus orbits Saturn more rapidly than the material in the F ring, each new channel is carved about 3.2 degrees in front of the previous one. This is an artists concept of Cassini during the Saturn Orbit Insertion (SOI) maneuver, just after the main engine has begun firing. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ...

Outer Rings

"Janus/Epimetheus" Ring

A faint dust ring is present around the region occupied by the orbits of Janus and Epimetheus, as revealed by images taken in forward-scattered light by the Cassini spacecraft in 2006. The ring has a radial extent of about 5,000 km ^[10]. Its source is particles blasted off the moons' surfaces by meteoroid impacts, which then form a diffuse ring around their orbital paths ^[11]. Janus (jay-nus, IPA: , Greek Ιανός) is an inner satellite of Saturn. ... Epimetheus (ep-i-mee-thee-us, Greek Επιμηθεύς) is a moon of Saturn. ... This is an artists concept of Cassini during the Saturn Orbit Insertion (SOI) maneuver, just after the main engine has begun firing. ...

G Ring

The G Ring is a very thin, faint ring about halfway between the F Ring and the beginning of the E Ring, with its inner edge about 15000 km inside the orbit of Mimas. It contains a single distinctly brighter "arc" near its inner edge (similar to the arcs in the rings of Neptune) that extends about one sixth of its circumference, which is held in place by a 7:6 orbital resonance with Mimas.^[12] The arc is believed to be composed of icy particles up to a few meters in diameter, with the rest of the G Ring consisting of dust released by collisions within the arc. The radial width of the arc is about 250 km, compared to a width of 6000 km for the G Ring as a whole.^[12] The arc is thought to be the remains of a small icy moonlet about a hundred meters in diameter that broke up relatively recently. Dust released from the larger chunks by micrometeoroid impacts drifts outward from the arc due to interaction with Saturn's magnetosphere (whose plasma corotates with Saturn's magnetic field, which rotates much more rapidly than the orbital motion of the G Ring). These tiny particles are steadily eroded away by further impacts and dispersed by plasma drag. Over the course of thousands of years the ring will gradually lose mass and eventually disappear.^[13] Mimas (mee-mÉ™s or mye-mÉ™s, IPA: , Greek Μίμᾱς, rarely Μίμανς) is a moon of Saturn that was discovered in 1789 by William Herschel. ... This is a list of the named rings and ring arcs of Neptune. ... In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other. ... A Micrometeoroid (also micrometeorite, micrometeor) is a tiny meteoroid; a small particle of rock from space, usually weighing less than a gram, that poses a threat to space exploration. ... This article is about the planet. ... A magnetosphere is the region around an astronomical object in which phenomena are dominated or organized by its magnetic field. ... For other uses, see Plasma. ... Magnetic field lines shown by iron filings Magnetostatics Electrodynamics Electrical Network Tensors in Relativity This box:      In physics, the magnetic field is a field that permeates space and which exerts a magnetic force on moving electric charges and magnetic dipoles. ...

"Pallene" Ring

A faint dust ring shares Pallene's orbit, as revealed by images taken in forward-scattered light by the Cassini spacecraft in 2006 ^[10]. The ring has a radial extent of about 2,500 km. Its source is particles blasted off Pallene's surface by meteoroid impacts, which then form a diffuse ring around its orbital path ^[11]. Discovery image of Pallene Pallene (pa-lee-nee, Greek Παλλήνη) is a natural satellite of Saturn. ... This is an artists concept of Cassini during the Saturn Orbit Insertion (SOI) maneuver, just after the main engine has begun firing. ...

E Ring

The E Ring is the outermost ring, and is extremely wide, beginning at the orbit of Mimas and ending somewhere around the orbit of Rhea. It is a diffuse disk of icy or dusty material. Unlike the other rings, it is composed of microscopic rather than macroscopic particles. In 2006, cryovolcanism on the moon Enceladus was determined to be the source of the E Ring's material. Mimas (mee-məs or mye-məs, IPA: , Greek Μίμᾱς, rarely Μίμανς) is a moon of Saturn that was discovered in 1789 by William Herschel. ... Atmosphere none Rhea (ree-a, Greek ‘Ρέα) is the second largest moon of Saturn and was discovered in 1672 by Giovanni Domenico Cassini. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... Ganesa Macula, a dark feature on Saturns moon Titan, might be a cryovolcanic dome. ... Atmosphere Surface pressure: trace, significant spatial variability[8][9] Composition: 91% Water vapour 4% Nitrogen 3. ...

The outer rings seen back-illuminated by the Sun. Image File history File links Saturn_outer_rings_labeled. ... Sol redirects here. ...

The backlit G Ring and its bright inner arc. This image is part of a movie sequence showing the arc's orbital motion that may be viewed here or here.

The backlit E ring, with Enceladus silhouetted against it at center. The moon's south polar jets erupt brightly below it, while tendrils of the E Ring wrap around it.

Possible ring system around Rhea

Main article: Rings of Rhea

Saturn's second largest moon Rhea may have a tenuous ring system of its own consisting of three narrow bands embedded in a disk of solid particles.^[14][15] These rings have not yet been imaged, but their existence has been inferred from Cassini observations in November of 2005 of a depletion of energetic electrons in Saturn's magnetosphere near Rhea. The Magnetospheric Imaging Instrument (MIMI) observed a gentle gradient punctuated by three sharp drops in plasma flow on each side of the moon in a nearly symmetric pattern. This could be explained if they were absorbed by solid material in the form of an equatorial disk containing denser rings or arcs, with particles perhaps several decimeters to approximately a meter in diameter. However, not all scientists are convinced that the observations were caused by a ring system. Atmosphere none Rhea (ree-a, Greek ‘Ρέα) is the second largest moon of Saturn and was discovered in 1672 by Giovanni Domenico Cassini. ... A magnetosphere is the region around an astronomical object in which phenomena are dominated or organized by its magnetic field. ... Cassini–Huygens is a joint NASA/ESA/ASI unmanned space mission intended to study Saturn and its moons. ...

References

Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 67th day of the year (68th in leap years) in the Gregorian calendar. ... Science is the journal of the American Association for the Advancement of Science (AAAS). ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 346th day of the year (347th in leap years) in the Gregorian calendar. ... 2008 (MMVIII) will be a leap year starting on Tuesday of the Anno Domini (common) era, in accordance with the Gregorian calendar. ... is the 24th day of the year in the Gregorian calendar. ... Nature is a prominent scientific journal, first published on 4 November 1869. ... Nature is a prominent scientific journal, first published on 4 November 1869. ... The Astronomical Journal is a monthly scientific journal published by the University of Chicago Press on behalf of the American Astronomical Society. ... Science is the journal of the American Association for the Advancement of Science (AAAS). ... is the 284th day of the year (285th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... The American Association for the Advancement of Science (AAAS) is an organization that promotes cooperation between scientists, defends scientific freedom, encourages scientific responsibility and supports scientific education for the betterment of all humanity. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... 2008 (MMVIII) will be a leap year starting on Tuesday of the Anno Domini (common) era, in accordance with the Gregorian calendar. ... is the 65th day of the year (66th in leap years) in the Gregorian calendar. ... This article is in need of attention. ... 2008 (MMVIII) will be a leap year starting on Tuesday of the Anno Domini (common) era, in accordance with the Gregorian calendar. ... is the 68th day of the year (69th in leap years) in the Gregorian calendar. ...

External links

• Planetary Rings Node: Saturn's Ring System
• Saturn's Rings by NASA's Solar System Exploration

See also

• Rings of Rhea
• Rings of Uranus
• Rings of Neptune
• Rings of Jupiter
• Édouard Roche - French astronomer who described how the breakup of a satellite could form the rings, when it comes within the Roche limit of a celestial body.
• Galileo Galilei - the first person to observe Saturn's rings, in 1610
• Christian Huygens - the first person to propose that there was a ring surrounding Saturn, in 1655
• Giovanni Cassini - discovered the gap between the A and B rings, in 1675 - (Cassini Division)

v • d • e Saturn
Major Moons	Mimas · Enceladus · Tethys · Dione · Rhea · Titan · Hyperion · Iapetus
Characteristics	Dragon Storm · Great White Spot · Rings of Saturn · Moons
Exploration	Pioneer 11 · Voyager program · Cassini–Huygens
Other	Saturn-crosser asteroid · Delta Octantis · Saturn kilometric radiation · Saturn in fiction