The Saturn ring is the most extensive ring system of any planet in the Solar System. They consist of countless small particles, ranging from m m to m in size, orbiting about Saturn. The ring particles are entirely made of water ice, with trace components of rocky material. There is no consensus on the mechanism of its formation; some ring features indicate relatively new origins, but theoretical models suggest they tend to have formed early in the history of the Solar System.
Although the reflections of the rings increase the brightness of Saturn, they are invisible from Earth with unattended sight. In 1610, the year after Galileo Galilei turned the telescope into the sky, he became the first to observe Saturn's rings, though he could not see them well enough to distinguish their true nature. In 1655, Christiaan Huygens was the first to describe them as the disks that surrounded Saturn. Although many people think Saturn's rings consist of a series of small circles (a concept that goes back to Laplace), the distance is a little right. It is more appropriate to regard the ring as an annular disk with concentric local maxima and minimum in density and brightness. On the lump scale inside the ring there is plenty of empty space.
The rings have many loopholes in which the density of the particles decreases sharply: two are opened by known moons embedded in them, and more in the locations of the destabilized orbital resonance known as the moons of Saturn. Other gaps remain unexplained. Resonance stabilizing, on the other hand, is responsible for the longevity of some rings, such as the Titan Ringlet and G Ring.
Far outside the main ring is the Phoebe ring, which is tilted at an angle of 27 degrees to another ring and, like Phoebe, orbits in retrograde mode.
Video Rings of Saturn
History
by Galileo
Galileo Galilei was the first to observe Saturn's rings in 1610 using his telescope, but could not identify them as such. He wrote to the Duke of Tuscany that "the Saturn Planet is not alone, but consists of three, who almost touch each other and never move or change against each other, they are arranged in parallel lines with the zodiac, and the middle (Saturn) - about three times larger than lateral. "He also described the ring as Saturn's" ear. " In 1612 Earth passes through the ring plane and they become invisible. Disgraced, Galileo commented, "I do not know what to say in such a surprising case, so unnoticed and so new." He muses, "Did Saturn swallow his children?" - Refers to the myth of the Saturn Titan devouring his descendants to prevent their prophecy overthrow him. He was more confused when the ring was re-visible in 1613.
Early astronomers used anagrams as a scheme of commitment to claim new discoveries before their results were ready for publication. Galileo used smaismrmilmepoetaleumibunenugttauiras for Altissimum planetam against observavi ("I have observed the most distant planets to have triple shapes") to find the rings of Saturn.
Ringing theory, observation and exploration
In 1655, Christiaan Huygens became the first to claim that Saturn was surrounded by a ring. Using the power refracting telescope 50ÃÆ' that he designed himself, is far superior than those available to Galileo, Huygens observed Saturn, and in 1656, such as Galileo, have published the anagram saying "aaaaaaacccccdeeeeeghiiiiiiillllmmnnnnnnnnooooppqrrstttttuuuuu". After confirming his observations, three years later he described it as "Annuto cingitur, tenui, plano, nusquam coherente, ad eclipticam inclinato"; namely, "It [Saturn] is surrounded by a ring that is thin, flat, does not touch anywhere, inclines to the ecliptic". Robert Hooke is an early observer of other Saturn rings, and records the shadow shooting on the rings.
In 1675, Giovanni Domenico Cassini determined that Saturn's rings consist of several small rings with a gap between them; the largest of these gaps was later named Cassini Division. This division is an area of ​​4,800 km between ring A and B Ring.
In 1787, Pierre-Simon Laplace proved that a uniform solid ring would become unstable and suggested that the rings consisted of a large number of solid ringlets.
In 1859, James Clerk Maxwell showed that a non-uniform solid ring, a solid ring or a continuous fluid ring would also be unstable, indicating that the ring must consist of many small particles, all orbiting Saturn independently. Later, Sofia Kovalevskaya also found that Saturn's rings can not be in the form of a liquid ring body. The study of ring spectroscopy performed in 1895 by James Keeler of the Allegheny Observatory and Aristarchh Belopolsky of the Pulkovo Observatory showed Maxwell's correct analysis.
Four robotic spacecraft have observed the rings of Saturn from around the planet. The closest approach of Pioneer 11 to Saturn occurred in September 1979 at a distance of 20,900 km. Pioneer 11 was responsible for the discovery of the F ring. The nearest approach to Voyager 1 occurred in November 1980 at a distance of 64,200 km. Photopolarimeter failed to prevent Voyager 1 from observing Saturn's ring at a planned resolution; Nevertheless, images from the spacecraft provide unprecedented detail of the ring system and reveal the existence of the G ring. The nearest approach of Voyager 2 occurred in August 1981 at a distance of 41,000 km. The working photopolarimeter of Voyager 2 makes it possible to observe the ring system at a higher resolution than Voyager 1, and thus finds many curls previously invisible. Cassini spacecraft entered orbit around Saturn in July 2004. Cassini The ring image is the most detailed to date, and is responsible for the discovery more ringlets.
Rings are named alphabetically in the order they are found. The main ring, working out of the planet, C, B and A, with the Cassini Division, the largest gap, separates Ring B and A. Some of the dim rings were found recently. D Ring is very unconscious and closest to the planet. The narrow F ring is outside the A Ring. Beyond that are two much more damper rings named G and E. The rings exhibit a large number of structures at all scales, some related to interference by the moons of Saturn, but many are unexplained.
Maps Rings of Saturn
Physical Characteristics
The dense main circle extends from 7,000 km (4,300 mi) to 80,000 km (50,000 mi) of Saturn's equator, whose radius is 60,300 km (37,500 mi) (see Major subdivision). With an approximate local thickness of at least 10 m and as much as 1 km, they consist of 99.9% pure ice water with a handful of impurities that may include tholins or silicates. The main ring consists mainly of particles ranging from 1 cm to 10 m.
Based on observations of Voyager , the total ring mass is estimated to be about 3Ã, ÃÆ' â € "10 19 kg. This is a fraction of the total mass of Saturn (about 50 ppb) and only slightly less than the mimas month. Recent observations and computer modeling based on observations of Cassini show that this may be underestimated because it clumps in the ring and the mass may be three times this number. Although the largest gaps in the ring, such as the Cassini and Encke Gap Divisions, can be seen from Earth, the two spacecraft Voyager found that the rings have intricate structures of thousands of thin slits and curls. This structure is thought to have appeared, in several different ways, from the gravitational pull of the moons of Saturn. Some of the gaps are cleared with small moons like Pan, many more are still to be found, and some curls seem to be retained by the gravitational effects of small shepherd satellites (similar to the maintenance of Prometheus and Pandora against the F ring). Another gap arises from the resonance between the periods of the particle orbital in the larger gap and out; Mimas maintains the Cassini Division in this way. There are still more structures in rings consisting of spiral waves elevated by periodic gravitational impairment of the deep moons in less disturbing resonances. Data from the space probe Cassini show that Saturn's ring has its own atmosphere, independent of the planet itself. The atmosphere consists of molecular oxygen gas (O 2 ) produced when the ultraviolet rays from the Sun interact with ice water in the ring. The chemical reactions between water molecule fragments and ultraviolet stimulation further create and exclude, inter alia, O 2 . According to this atmospheric model, H 2 is also present. The atmosphere of O 2 and H 2 is so rare that if the entire atmosphere is condensed into a ring, it will be about one atom thick. This ring also has a similar OH (hydroxide) atmosphere. Like O 2 , this atmosphere is produced by the disintegration of water molecules, although in this case disintegration is done by energetic ions bombarding water molecules released by Saturn's moon Enceladus. This atmosphere, though very rarely, is detected from Earth by the Hubble Space Telescope. Saturn shows a complicated pattern in its brightness. Most of the variability is due to the changing aspect of the ring, and this goes through two cycles of each orbit. However, superimposed on this is the variability due to the eccentricity of planetary orbits that cause the planet to show brighter opposition in the northern hemisphere than in the south.
In 1980, Voyager 1 produced a Saturn fly-by which showed an F-ring consisting of three narrow rings that seemed to be braided in an intricate structure; it is now known that the two outer circles are made up of knobs, knots and blobs that give the illusion of braids, with the third unlit ring lying in them.
The new images of rings taken around August 11, 2009 of the Saturnian equinox by the NASA spacecraft Cassini have shown that the longitudinal rings are significantly out of the plane of nominal rings in some places. This displacement reaches as much as 4 km (2.5 mi) on the Gap Keeler border, due to the orbit outside the Daphnis plane, the moon that created the gap.
The main ring formation
Saturn's rings may be very old, dating the Saturn formation itself. There are two main theories about the origin of the inner ring of Saturn. One theory, originally proposed by Douard Roche in the 19th century, is that the ring was once the moon of Saturn (named Veritas, after a Roman goddess hiding in a well) whose orbit decays until it comes close enough to be torn apart- shreds. separated by tidal forces (see Roche boundary). The variation on this theory is that this moon is destroyed after being attacked by a large comet or asteroid. The second theory is that the rings were never part of the moon, but instead remained of the original nebular material from which Saturn was formed.
The more traditional version of the moon-disrupted theory is that the rings consist of debris from the moon 400 to 600 km in diameter, slightly larger than Mimas. The last time there was a large enough collision to be able to disrupt the big moon was at the End of the Heavy Bombering about four billion years ago.
A newer variation of this type of theory by RM Canup is that the rings can represent a portion of the ice mantle remnants of a much larger, differentiated, Titan-sized mantle stripped from its outer layers as it spins onto the planet. during the formative period when Saturn is still surrounded by a gas nebula. This will explain the scarcity of the rocky material inside the ring. The ring will initially be much larger (? 1,000 times) and wider than it is today; the material on the outside of the ring will unite into Saturn's moon to Tethys, also explaining the lack of rocky material in composition most of these months. The ensuing collisional or cryovolcanic evolution of Enceladus may have resulted in selective loss of ice from this month, increasing its density to a current value of 1.61 g/cm 3 , compared to 1.15 for Mimas and 0 , 97 for Tethys.
The idea of ​​the enormous early rings was then extended to explain the formation of the moons of Saturn to Rhea. If the initial large rings contain pieces of rocky material (& gt; 100 km across) and ice, this silicate body will add more ice and have been removed from the ring, due to the gravitational interaction with the ring and tidal interactions with Saturn, to an increasingly widespread orbit. Within the Roche boundary, the rocky material body is dense enough to accumulate additional material, whereas less dense ice objects do not. Once outside the circle, newly formed moons can continue to evolve through random mergers. This process can explain the variation of the silicate content of the moons of Saturn to Rhea, and the tendency toward silicate content closer to Saturn. Rhea will be the oldest month of the moons formed from primordial rings, with the moons closer to the younger Saturn.
The brightness and purity of water ice in Saturn's rings has been cited as evidence that the ring is much younger than Saturn, perhaps only 100 million years, because metallic dust infall will cause ring fogging. However, new research suggests that Ring B may be large enough to thin the infall material and avoid substantial embezzlement over the age of the Solar System. The ring material can be recycled as the clumps form inside the ring and are then disturbed by the impact. This will explain the youth seen from some matter in the ring. Further evidence supporting the young ring theory has been collected by the researchers analyzing data from the Titan Radar Cassini Mapper, which focuses on analyzing the proportions of silicate rocks contained in the C ring.
The UVIS Cassini team, led by Larry Esposito, uses the occult star to find 13 objects, ranging from 27 m to 10 km, within the circle F. They are translucent, indicating they are a temporary aggregate of ice cubes several m across. Esposito believes this to be the basic structure of Saturn's rings, the particles that clot, then blown up.
Subdivisions and structures in circles
The densest parts of Saturn's ring system are Ring A and B, 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 has characters similar to the Cassini Division, this region is the main ring of . The main ring is denser and contains larger particles than the weak dusty ring . The latter include the D Ring, extending inward to the top of the clouds of Saturn, G and E Rings and others outside the main ring system. These diffuse rings are characterized as "dusty" because of their small particle size (often about one m); Its chemical composition, like the main ring, is almost entirely water ice. The narrower F ring, outside the outer edge of the A Ring, is harder to categorize; the parts are very dense, but also contains many particles of dust size.
Physical parameters of the ring
Note:
(1) Name designated by International Astronomical Union, unless otherwise stated. A wider separation between named rings is named after division , while the narrower separation in the named circle is called slit .
(2) Data mostly from the Planet Nomenclature layout, NASA fact sheets and some papers.
(3) distance to center of crevice, ring and narrower circle of 1,000 km
(4) unofficial name Major subdivisions
Structure C Ring
Cassini Division Structure
Ring Structure
D Ring
The D Ring is the deepest ring, and very unconscious. In 1980, Voyager 1 was detected in this ring three ringlets designated D73, D72 and D68, with D68 being the discrete ringlet closest to Saturn. About 25 years later, Cassini's image shows that D72 has become wider and more diffuse, and has moved to the planet as far as 200 km.
Comes in D Ring is a finescale structure with 30 km of waves. First seen in the gap between C Ring and D73, the structure was discovered during Saturn's 2009 equinox to extend a radial distance of 19,000 km from D Ring to the inside edge of B Ring. Waves are interpreted as vertical wrinkle spiral patterns of amplitude 2 to 20 m; The fact that the wave period declined over time (from 60 km in 1995 to 30 km in 2006) allowed the deduction that the pattern probably originated in late 1983 with the impact of clouds of debris (with the mass of 10 12 kg) of the disturbed comet that tilts the ring out of the equatorial plane. The same spiral pattern on Jupiter's main ring has been attributed to the disruption caused by the material impact of Comet Shoemaker-Levy 9 in 1994.
C Ring
Ring C is a wide but vague ring located within Ring B. It was discovered in 1850 by William and George Bond, although William R. Dawes and Johann Galle also saw it independently. William Lassell termed it the "Crepe Ring" because it seemed to consist of darker material than the brighter A and B Rings.
The vertical thickness is estimated at 5 m mass of about 1.1 ÃÆ'â € "10 18 kg, and the optical depth varies from 0.05 to 0.12. That is, between 5 to 12 percent of light shines perpendicularly through a blocked ring, so that when viewed from above, the ring is close to transparent. The 30-km wavelength spiral wave was first seen on D Ring observed during the equinox saturn of 2009 to extend along the C Ring (see above).
Colombo's Gap and Titan Ringlet
The Colombo Gap is located inside the C Ring. Inside the gap is the light but narrow Ringlet Colombo, centered at 77,883 km from the center of Saturn, which is slightly elliptical and not round. This Ringlet is also called the Titan Ringlet because it is governed by orbital resonance with the Titan of the moon. At this location inside the ring, the length of the rosary particle prupion of the particle equals the length of the Titan's orbitals, so that the outer edge of this eccentric ring always leads to the Titan.
Maxwell Gap and Ringlet
Maxwell's gap is located on the outside of the Ring C. It also contains a solid non-circular ringlet, Maxwell Ringlet. In many ways this ring is similar to? Uranus rings. There is a wave-like structure in the middle of both rings. While the waves on? the ring is thought to be caused by the Uranian moon Cordelia, no moon was found in Maxwell's gap in July 2008.
B Ring
Ring B is the largest, brightest, and most massive ring. Its thickness is estimated as 5 to 15 m and the optical depth varies from 0.4 to greater than 5, which means that & gt; 99% of the light passing through some parts of Ring B is blocked. Ring B contains many variations in its density and brightness, almost unexplained. It is concentric, appears as a small circle, although the B Ring does not contain a gap. In places, the outer edge of the B Ring contains a vertical structure that deviates up to 2.5 km from the main ring area.
A 2016 study of spiral density waves using star occultation shows that the surface density of Ring B is in the range of 40 to 140 g/cm 2 , lower than previously believed, and that the optical depth of the ring has little correlation with its mass density (previously reported findings for A and C rings). The total mass of Ring B is estimated to be somewhere in the range of 7 to 24 ÃÆ' - 10 18 kg. Compare with mass for Mimas 37,5 ÃÆ' - 10 18 kg.
Fingers
Until 1980, Saturn's ring structure was described as exclusively caused by the action of gravity. Then the image of the Voyager spacecraft shows a radial feature in Ring B, known as radius , which can not be explained in this way, because the persistence and rotation around the ring is inconsistent with the mechanics of gravitational orbitals. His fingers look dark in the backscattered light, and bright in the forward-forward light (see picture in Gallery); transition occurs at a phase angle near 60 °. The main theory about the composition of spokesmen is that they are composed of microscopic dust particles that are kept away from the main ring by electrostatic repulsion, since they rotate almost simultaneously with Saturn's magnetosphere. The exact mechanism of producing radii is still unknown, although it has been suggested that electrical disturbance may be caused by one of the lightning bolts in the Saturn atmosphere or the micrometeoroid impact on the ring.
The fingers were not observed again until about twenty-five years later, this time by the Cassini space probe. The fingers were not visible when Cassini arrived at Saturn in early 2004. Some scientists speculated that the fingers would not be seen again until 2007, based on models trying to describe their formation. Nevertheless, Cassini's imaging team continues to look for fingers in the ring image, and they are subsequently seen in the pictures taken on September 5, 2005.
The fingers appear to be a seasonal phenomenon, disappearing in mid-winter Saturn and mid-summer and reappear as Saturn gets closer to the turning point. The suggestion that the fingers could be a seasonal effect varies with Saturn's 29.7-year orbit, supported by gradual reappearance in subsequent years of Cassini's mission.
Moonlet
In 2009, during the equinox, a moonlet embedded in the B ring was found from a casting shadow. Expected to be 400 m (1,300 ft) in diameter. Moonlet was given a temporary appointment S/2009 S 1.
Cassini Division
The Cassini division is an area of ​​4,800 km (3,000 mi) wide between Saturn A ring and B Ring. It was discovered in 1675 by Giovanni Cassini at the Paris Observatory using a refractive telescope that has a 2.5-inch objective lens with a 20-foot-long focal length and 90x magnification. From the Earth it appears as a thin black slit in the ring. However, Voyager found that the gap itself is inhabited by a ring material that has much in common with C Ring. The division may appear bright in the non-light side view of the ring, because the relatively low material density allows more light to be transmitted through ring thickness (see the second image in the gallery).
The inner edges of the Cassini Division are governed by strong orbital resonances. The ring particles at this location orbit twice for every orbit of the mimas month. Resonance causes Mimas to pull these ring particles to accumulate, destabilize its orbit and lead to a sharp cutoff in ring density. However, many other gaps between curls in the Cassini Division can not be explained.
Huygens Gap
Huygens Gap is located inside the Cassini Division. It contains a dense, eccentric Huygens Ringlet in the middle. This ringlet shows irregular azimuth variation of geometric width and optical depth, which may be caused by the 2: 1 resonance closest to Mimas and the eccentric outer edge influence of the B-ring. There is an extra narrow ringlet outside the Huygens Ringlet.
A Ring
The A Ring is a large and bright outer ring. The inner boundary is the Cassini Division and its sharp outer border is close to the small Atlas moon's orbit. A Ring is cut off at 22% of the ring width from its outer edge by Encke Gap. The narrow gap of 2% of the ring width from the outer edge is called Gap Keeler.
The thickness of Ring A is estimated to be 10 to 30 m, its surface density from 35 to 40 g/cm 2 and its total mass as 4 to 5 ÃÆ'â € " 10 18 kg (just below the Hyperion mass). The optical depth varies from 0.4 to 0.9.
Similarly with B Ring, the outer edge of A Ring is maintained by orbital resonance, in this case a 7: 6 resonance with Janus and Epimetheus. Other orbital resonances also generate many waves of spiral density in Ring A (and, to a lesser degree, other rings as well), which explains most of its structure. This wave is explained by the same physics that describes the galactic spiral arms. Spiral bending waves, also present in Ring A and also described by the same theory, are vertical wrinkles in rings rather than compressed waves.
In April 2014, NASA scientists reported observing possible formative stages of the new moon near the outer edge of the A Ring.
Encke Gap
The Encke Gap is a 325-km-wide gap in the A ring, centered on a distance of 133,590 km from the center of Saturn. This is due to the presence of a small moon Pan, which orbits inside it. Images from the Cassini probe have shown that there are at least three small circles tied in the gap. The spiral density waves seen on both sides are induced by resonance with the nearest moon exterior to the ring, while Pan induces an additional set of spiral wakes (see picture in gallery).
Johann Encke himself did not notice this gap; it is named in honor of his ring observations. The gap itself was discovered by James Edward Keeler in 1888. The second major gap in the A ring, invented by Voyager, was named Keeler Gap in his honor.
The Encke Gap is slit because it is fully within Circle A. There is some ambiguity between the terms gap and division until the IAU clarifies the definition in 2008; before that, the separation was sometimes called "Encke Division".
Keeler Gap
The Keeler Gap is a 42-km-wide gap in the A ring, about 250 km from the outer edge of the ring. The small moon of Daphnis, discovered May 1, 2005, orbits inside it, keeping it clear. The moon section induces waves at the edge of the gap (this is also influenced by the small eccentricity of its orbital). Because the Daphnis orbit is slightly inclined towards the ring plane, the waves have a component perpendicular to the ring plane, reaching a distance of 1500 m "above" the plane.
Keeler's gap is discovered by Voyager , and is named in honor of astronomer James Edward Keeler. Keeler in turn found and named Encke Gap in honor of Johann Encke.
Moonlet propeller
In 2006, four small "small moons" were found in Cassini's image of Ring A. The Moonlet itself was only about a hundred meters in diameter, too small to be seen directly; what Cassini sees is a "propeller" disorder made by the moonlet, which is a few km away. It is thought that A Ring contains thousands of such objects. In 2007, the discovery of eight full moons revealed that they were largely confined to a 3,000 km belt, about 130,000 km from the center of Saturn, and in 2008 more than 150 moon propellers had been detected. One that has been tracked for several years has been dubbed Bleriot .
Roche Division
The separation between ring A and F Ring has been named the Roche Division in honor of the French physicist ÃÆ' â € ° douard Roche. Roche's division should not be confused with the Roche boundary which is the distance at which the big object is so close to the planet (like Saturn) that the tidal force of the planet will pull it apart. Lying on the outer edge of the main ring system, Roche Division is actually close to the boundary of Roche Saturn, which is why the ring can not result into a moon.
Like the Cassini Division, Roche's Division is not empty but contains a piece of material. The character of this material is similar to D, E, and G Rings that are tenuous and dusty. Two locations in the Roche Division have higher dust concentrations than other regions. It was discovered by the Cassini probe imaging team and was given a temporary title: R/2004 S 1, which lies along the orbit of the Atlas of the moon; and R/2004 S 2, centered on 138,900 km from the center of Saturn, within the orbit of Prometheus.
F Ring
The F Ring is Saturn's outermost discrete rings and is probably the most active ring in the Solar System, with features changing on a time scale of many hours. It is located 3,000 km outside the outer edge of the A ring. The ring was discovered in 1979 by the Pioneer 11 imaging team. It is very thin, just a few hundred miles in radius radius. While the traditional view has been held together by two months of herders, Prometheus and Pandora, orbiting inside and outside it, recent studies show that only Prometheus contributed to the confinement. Numerical simulations show the ring was formed when Prometheus and Pandora collided with each other and partly interrupted.
The latest closeup image of the Cassini probe shows that Ring F consists of one core ring and a spiral strand around it. They also show that when Prometheus finds a ring in his apoapsis, his gravitational attraction creates a tangle and a knot in the F Ring as a matter of 'stealing' the moon from it, leaving the dark ducts on the inside of the ring (see video link and additional F Ring image in the gallery). Because Prometheus orbits Saturn faster than the material in the F ring, each new channel is carved about 3.2 degrees ahead of the previous one.
In 2008, further dynamism was detected, indicating that the small invisible moons orbiting within the F Ring continuously pass through its narrow nucleus due to impairment from Prometheus. One such small moon was temporarily identified as S/2004 S 6.
Outside circle
Janus/Epimetheus Ring
A faint dust ring is present around the area occupied by the orbits of Janus and Epimetheus, as revealed by images taken in light forwarded by the Cassini spacecraft in 2006. The ring has a radial area of ​​about 5,000 km. The source is the particles that are detonated from the lunar surface by the impact of the meteoroids, which then form a ring spreading around its orbital path.
G Ring
G Ring (see last picture in the gallery) is a very thin and weak ring about halfway between the F Ring and the beginning of the E Ring, with an inside tip of approximately 15,000 km in the orbit of Mimas. It contains a clearly lighter arc near the inner edge (similar to the bow on Neptune's ring) that extends about one-sixth of its perimeter, centered on the half-moon of Aegaeon's diameter crescent, held in place by 7: 6 orbital resonance with Mimas. The bow is believed to consist of particles of ice up to several m in diameter, with the remaining G Ring consisting of dust released from within the arc. The radial width of the arc is about 250 km, compared to the width of 9,000 km for the G Ring as a whole. The bow is thought to contain the material equivalent to a small moon of ice about a hundred m in diameter. The dust released from Aegaeon and other source bodies in the arc by the effects of micrometeoroids drifts out of the arc because of interaction with the Saturn magnetosphere (the plasma is correlated with the Saturn magnetic field, which rotates much faster than the Ring's orbital movement). These small particles continue to be eroded by further impact and spread by plasma drag. For thousands of years the ring gradually lost mass, which was replenished by further impact on Aegaeon.
Ring Finger Arc
The faint ring bows, first detected in September 2006, which includes a longitudinal level of about 10 degrees are associated with the Methone moon. The material in the arc is believed to represent the dust released from the Methone by the effects of micrometeoroids. The confinement of dust inside the arc is caused by the resonance of 14:15 with Mimas (similar to the arc restraint mechanism inside the G ring). Under the same resonance effect, the Methone rotates back and forth in its orbit with an amplitude of 5 Â ° longitude.
Antre Ring Arc
The faint ring bows, first detected in June 2007, covering a 20-degree longitudinal area linked to Anthe month. The material in the arc is believed to represent the dust thrown from Anthe by the impact of micrometeoroid. The confinement of dust inside the arc is caused by a 10:11 resonance with Mimas. Under the same resonance effect, Anthe drifted back and forth in its orbit over 14 Â ° Longitude.
Pallene Ring
A faint dust ring shares Pallene's orbits, as revealed by images taken in light forwarded by the Cassini spacecraft in 2006. The ring has a radial width of about 2,500 km. The source is a particle thrown from the surface of Pallene by the impact of a meteoroid, which then forms a ring spreading around its orbital path.
E Ring
E Ring is the second and very wide outer ring; it consists of many small particles (microns and sub-microns) of water ice with silicates, carbon dioxide and ammonia. E Ring is distributed between Mimas and Titan orbitals. Unlike other rings, they are made up of microscopic particles rather than macroscopic pieces of ice. In 2005, the E Ring material source was determined to be cryovolcanic blobs derived from "tiger stripes" in the south pole of Enceladus moon. Unlike the main ring, Ring E is 2,000 km thicker and increases with distance from Enceladus. The tendril-like structure observed in the E Ring can be attributed to the most active south pole jet emission of Enceladus.
E Ring particles tend to accumulate in the orbiting months in them. Tethys front hemisphere is blue due to infall material. Months of Telesto, Calypso, Helene and Polydeuces trojans are severely affected as their orbits move up and down the ring plane. This causes the surface to be coated with bright material that smooths the feature.
Phoebe Ring
In October 2009, the discovery of a weak disc of inner material only into the orbit Phoebe was reported. The disk is parallel to the edge to Earth at the time of discovery. This disk can be described loosely as another ring. Although very large (as seen from Earth, the real size of two full moons), the rings are almost invisible. It is found using NASA's infrared Spitzer Space Telescope, and is seen throughout the observation range, which extends from 128 to 207 times the radius of Saturn, with calculations showing that it can extend out to 300 Saturn radius and into orbit Iapetus in 59 Saturn radius. The ring was then studied using the WISE, Herschel and Cassini spacecraft; Wise observations show that it extends from at least between 50 and 100 to 270 Saturn radii (the inner edges are lost in planetary light). Data obtained with WISE show small ring particles; those with a radius greater than 10 cm comprise 10% or less of the cross-sectional area.
Phoebe orbits the planet at a distance from 180 to 250 fingers. The ring has a thickness of about 40 radii. Because the ring particles are thought to be of impact (micrometeoroid and larger) on Phoebe, they must share a retrograde orbit, which is opposite to the orbital movement of the next inner moon, Iapetus. This ring lies in the orbital plane of Saturn, or approximately ecliptic, and is therefore tilted 27 degrees from the equatorial plane of Saturn and other rings. Phoebe tends to be 5 Â ° with respect to the orbital plane of Saturn (often written as 175 Â °, due to the Phoebe retrograde orbital movement), and the resulting vertical travels above and below the ring area agree closely to the observed thickness of the ring of 40 Saturn- finger.
The existence of the ring was proposed in 1970 by Steven Soter. The discovery was made by Anne J. Verbiscer and Michael F. Skrutskie (from the University of Virginia) and Douglas P. Hamilton (from University of Maryland, College Park). All three studied together at Cornell University as graduate students.
The ring material migrates inward because of the rejection of solar radiation, at a rate inversely proportional to the particle size; 3 cm particles will migrate from about Febe to Iapetus over the age of the Solar System. The material will attack the prominent part of Iapetus. This infall material causes a bit of darkness and flushed from the frontal part of Iapetus (similar to what was seen in Uranian moon Oberon and Titania) but did not directly create the dramatic two-tone color of the moon. Instead, the infalling material initiates a positive thermal self-segregation feedback process from the sublimation ice of the warm region, followed by condensation of the vapor to the cold region. This leaves the dark residue of "lag" material covering most of the equatorial region of the main hemisphere of Iapetus, which contrasts with the bright ice deposits that cover the polar regions and most of the remaining hemisphere.
Ringing system that allows around Rhea
Saturn's second largest moon Rhea has been hypothesized to have its own loose ring system consisting of three narrow bands embedded in solid particle disks. This putative ring has not been imaged, but their existence has been deduced from the observations of Cassini in November 2005 from the depletion of energetic electrons in the magnetosphere of Saturn near Rhea. The Magnetospheric Imaging Instrument (MIMI) observes a soft gradient interspersed by three sharp drops in the plasma stream on each side of the moon in an almost symmetrical pattern. This can be explained if they are absorbed by solids in the form of an equatorial disk containing a more dense ring or arc, with particles perhaps several dm to about one m in diameter. A newer piece of evidence that is consistent with the presence of the Rhean ring is a set of small bright ultraviolet points distributed in a line that extends three quarters of the way around the perimeter of the moon, within 2 degrees of the equator. Spots have been interpreted as an impact point of the deorbiting ring material. However, the observations targeted by Cassini from the putative ring plane from several angles showed nothing, suggesting that another explanation for this enigmatic feature is required.
Gallery
See also
- Galileo Galilei - the first person to observe Saturn's rings, in 1610
- Christiaan Huygens - the first to suggest that there is a ring around Saturn, in 1655
- Giovanni Cassini - discovered the separation between A and B rings (Cassini Division), in 1675
- ÃÆ' â € ° Douard Roche - A French astronomer describing how satellites that fall within the Roche Saturn limit can break down and form a ring
Note
References
External links
- Planet Node Ring: The Saturn Ring System
- Saturn's Ring by NASA Solar System Exploration
- Ring of Saturn nomenclature from the USGS planet nomenclature page
- The Biggest Ring Around New Saturn is Prepared (taken 2017-12-20 from Space.com)
- All Curious Minds Need to Know About the Planet Rings System with Dr. Mark Showalter (Waseem Akhtar podcast with Mark Showalter)
- High-resolution animation by SeÃÆ'¡n Doran from the backlight ring
Source of the article : Wikipedia
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