Our Solar System consists of the Sun and planets, stars, comets, asteroids and other cosmic bodies. Today we will talk about planets that are surrounded by rings. You will learn which planets have rings from this article.
What is the name of a planet with rings?
Mostly only giant planets have rings, which we will talk about below. The rings are formations of dust and ice that rotate around celestial body. They are concentrated near the equator and thereby form thin lines. This feature is associated with the axial rotation of the planets: a stable gravitational field is present in the equatorial zone. This is what keeps the rings around the planet.
Which planets have rings?
In our solar system, the giant planets have rings. The largest and most clearly visible rings are Saturn. They were first discovered in 1659 by the Dutch astronomer Christiaan Huygens. There are 6 rings in total: the largest of them is divided into thousands of small rings. They consist of pieces of ice of different sizes.
At the end of the twentieth century, when spaceships and precision telescopes were invented, scientists saw that not only Saturn had rings. In 1977, during research Uranus, a glow was noticed around him. It turned out that these were rings. So 9 rings were discovered, and Voyager 2 in 1986 discovered 2 more rings - thin, narrow and dark.
In 1979, the Voyager 1 spacecraft discovered rings around the planet. Jupiter. Its inner ring is weak and is in contact with the planet's atmosphere. And finally, in 1989, Voyager 2 discovered around Neptune 4 rings. Some of them had arches, areas where there was an increased density of matter.
However, modern high-precision technology has made it possible to discover new secrets of our system. Recent research by scientists has shown that Saturn's moon Rhea has rings. Also, the dwarf planet Haumea, which rotates in the peripheral part of the Solar System, has its own ring system.
Among the general enthusiasm that gripped scientists at the beginning of the 17th century in connection with stunning discoveries, one of them went almost unnoticed. In 1610, Kepler received from his great Italian colleague an anagram that read: “I observe the most distant triple planet...”. At the end of 1610, Galileo wrote to one of his correspondents: “I found a whole courtyard with two servants of the Old Man (Saturn); they support him in the procession and do not leave his sides.” And suddenly these satellites... disappeared, at least from the field of view of the telescope. Amazed, Galileo looked at the sky again and again, but did not see them. Only Huygens in The Hague, 45 years after Galileo's first observations, managed to understand to some extent the mystery of Saturn. Comparing his own and other people's observations, he came to the conclusion that the “satellites” discovered by Galileo were simply the ears of a thin, flat ring, almost continuous, inclined to the plane of the ecliptic.
Therefore, it can be seen from Earth in different ways. Twice during a Saturnian year, the ring can be positioned so that its plane becomes parallel to the line of sight. The ring is not visible from the edge; it is very thin.
Saturn's ring is a remarkable object to observe even with small telescopes. Its complete disclosure or disappearance is repeated after 14-16 years. The discovery of this extraordinary phenomenon did not attract, however, special attention scientists. It was a period of great revolutionary events in astronomy. The discovery of a strange ring around Saturn sunk among them.
Some astronomers of the 18th and early 19th centuries assumed that the ring could be solid and solid or consist of a series of thin continuous rings, solid or liquid. But already by the fifties of the 19th century, it became clear to astronomers who observed the ring that it could not be a solid body, but must consist of individual particles - dust particles or stones, each of which, as an independent satellite, revolves around Saturn.
In the seventies of the 19th century, the most complete study of the structure and stability of the ring was carried out by the famous Russian female mathematician Sofia Kovalevskaya. Her conclusions were soon brilliantly confirmed by spectroscopic observations. The ring, indeed, turned out to consist of many independent satellites. But where did this ring on Saturn come from?
Astronomers of the 19th century and many scientists of our time, considering the ring stable, declared it to be a remnant of the primordial material (from which the planet was formed), or the result of the disintegration of one of Saturn’s satellites, which entered a dangerous zone near the planet, where powerful tidal forces could tear it apart. It’s interesting to remember: the ancient Greeks had a myth that Saturn devoured his children.
Since the 50s of the last century, astronomical observatories, armed with increasingly sophisticated telescopes, began to note numerous changes in the structure of the ring. Some parts of it either became bright or were barely noticeable. At the same time, Otto Struve at the Pulkovo Observatory suspected a gradual expansion of the ring and the approach of its inner edge to the surface of the planet. Comparing precise measurements of the ring sizes made by scientists over 200 years, he found that over two centuries the inner edge of the ring approached the planet by 18 thousand kilometers. Modern observations seem to confirm the expansion of the ring, although the figures are somewhat different.
New information about the nature of Saturn's rings was brought by the use of powerful means of astrophysics. Back at the end of the 19th century, A. A. Belopolsky (Pulkovo Observatory) noted that the brightness distribution in the spectrum of the ring is not the same as in the spectrum of the planet itself. The remarkable photographs taken by G. A. Tikhov in 1909 using the giant 30-inch Pulkovo telescope clearly show that the ring is much “bler” than the planet. In the thirties, this issue was studied in detail by G. A. Shain at the Simeiz Observatory. The results of these studies and a number of later works led astronomers to the belief that in some parts of the ring, in addition to solid particles and bodies of a meteorite nature, there is ice and a certain amount of gas.
But ice in a free state cannot exist for a long time even at such a huge distance from where Saturn moves (9.5 astronomical units). Up to 11 astronomical units, i.e., up to a distance of 1.7 billion kilometers, the sun's rays must hit the ice, throwing the resulting gas particles out of the solar system. We observe such a process in which rapidly evaporating frozen gases form the head and tail of a comet.
But if the ring is constantly losing substance, then it must receive replenishment from somewhere. Outside, outside the Saturn system? This is impossible! The replenishment of ring matter and, consequently, the formation of the ring itself can only be explained by emissions from the Saturn system, powerful eruption processes both on the surface of Saturn’s satellites and, possibly, on the planet itself.
The conclusion about powerful volcanic activity in the Saturn system is quite consistent with what observers have repeatedly noted on the very surface of the planet. More than once, the appearance of bright white spots was observed there, sometimes existing for months. And later I came to the idea of gigantic ejections of matter from Saturn based on completely different considerations. The study of... comets led me to this conclusion.
Scientists have determined the orbits of 573 comets to date. 442 comets have orbital periods greater than 1,000 years, and the motion patterns of some of them indicate that they are leaving the solar system forever. 75 comets move in small elliptical orbits with an orbital period of less than 15 years. These are the so-called comets of the family. And the remaining 56 comets have orbital periods from 15 to 1000 years. These include, in particular, the comet families of Saturn, and.
The predominance of comets with very elongated parabolic orbits led to the idea that comets come from interstellar space, and most of them only pass through the Solar System. This hypothesis was expressed and mathematically developed more than two centuries ago by the French scientist Laplace.
But she failed the subsequent exams that many astronomers and mathematicians gave her. If comets were bodies of an interstellar nature, we should observe sharply hyperbolic orbits, but this is not the case.
If you love chess, then you have probably encountered problems involving retrograde analysis. Their meaning is that, given a position on the board, one must reconstruct the series of moves that led to it. A similar problem was solved by astronomers. For many comets for which a weakly hyperbolic motion was noted, all disturbances from the planets were calculated in order to find out what the orbit was before entering the region of planetary influence. In all cases, the initial orbit turned out to be elliptical, indicating that the comets belonged to the Solar System.
Accurate astrophysical research and the use of photometry and spectral analysis methods have made it possible to determine the composition of comets. The luminous heads and tails of comets consist of extremely rarefied gases (mainly hydrocarbons, cyanogen, carbon monoxide, molecular nitrogen, etc.), mainly in the form of ionized atoms and molecules. The cometary gases are undoubtedly products of the breakdown of more complex parent molecules under the influence of solar radiation. Comet nuclei must be composed of solid particles. Recently, it has been proven that the gases in comets are in a frozen state, in the form of ice, often “contaminated” with the inclusion of tiny dust.
A fact of exceptional importance was also established: comets are rapidly weakening. From appearance to appearance they become less and less bright and after 10-20 appearances they weaken tens and hundreds of times!
It became clear that comets were rapidly depleting the gas-forming materials from which the nebulous heads and tails of comets arise. Consequently, comets must have appeared quite recently in the region of the planets. Astronomers have determined the ages of many comets. It turned out to be very small: only a few hundred, and sometimes even tens of years. But how can we explain the existence of a large number of short-period comets?
Laplace believed that they were simply “prisoners” of the large planets, especially Jupiter, who intercepted them along the way and forced them to change their orbits, which had previously been parabolic. But many features of the movement of comets spoke against Laplace. On the contrary, it seems that comets are now, in our time, born in the solar system and that they have a certain relationship with the Jupiter system, since all short-period comets are closely associated with this planet. Initially, it was assumed that they were ejected directly from the surface of Jupiter and other large planets. But then it turned out that the assumption of the ejection of comets from the surface of Jupiter’s satellites corresponds even better to observations.
Meanwhile, other remarkable features of comets were revealed. In terms of their composition, cometary ices turned out to be extremely close to the gases of planetary atmospheres and, in particular, the atmospheres discovered on the satellites of Saturn and Neptune - Titan and Triton. A number of data suggested that the large moons of Jupiter are covered with a layer of frozen atmosphere, i.e., ice.
Many comets are accompanied by meteor showers. These two phenomena are related by at least a common origin. And the study of meteorites in laboratories, the study of their structure and chemical composition leads to the conclusion that they are fragments of the crust of planetary bodies. The largest Russian volcanologist and meteorite specialist A.N. Zavaritsky found that most stone meteorites are very close in structure to tuff rocks of the volcanic regions of the Earth. Even earlier, another outstanding mineralogist V.N. Lodochnikov came to the conclusion about the possibility of the formation of meteorites and streams of meteoric bodies during giant terrestrial eruptions.
The lifetime of meteor showers also turns out to be no more than several hundred or thousand years. The nature of the orbits suggests that the meteor particles belong to the solar system and undoubtedly formed within it. This means that the meteor showers that we are now observing must be of very recent origin.
The association of meteor showers with comets is further evidence of the volcanic or explosive origin of small solar system bodies. Any eruption must be accompanied by the release of enormous quantities of ash and sand, which will form meteor showers in the solar system.
These were the grounds that formed the basis of the assumption that the ring of Saturn is of a comet-meteorite nature. But why, in only one particular case with Saturn, did nature not skimp on a ring for the planet? This is wrong. Clouds consisting of comets and meteorite bodies, that is, rocks and ash particles, should also revolve around Jupiter. An eruption on a satellite of Jupiter must give the substance a speed of 5-7 kilometers per second in order to form a new comet. But significantly more stones and particles will have lower velocities; Jupiter will hold them with its gravity and gather them around itself in the form of a ring.
Where is it? After all, near Jupiter we do not observe such a bright and noticeable formation as the ring of Saturn. The thing to keep in mind here is that even if Jupiter had a ring as massive as Saturn's, we wouldn't see anything like what we see on Saturn. The fact is that the plane of Saturn’s equator is inclined to the ecliptic (i.e., the plane of motion of the planet) by 28°, which is why we can see the ring “opened,” while Jupiter’s inclination is only 3° and, therefore, the ring of Jupiter is We are always visible from the edge (just as it happens during periods of “disappearance”). When, as a result of the movement of Saturn and the Earth, we find ourselves close to the plane of the ring, it disappears; the ears are not visible, and on the planet’s disk along the equator there is a dark stripe - the “ring shadow”.
To be continued.
P.S. What else are British scientists thinking about: that, sooner or later, people will still be able to colonize other planets of our solar system. And then on the surface of Saturn or Jupiter some kind of water deferrization station will be quite common. But for now it all sounds like science fiction.
Do you know how many planets in the solar system have rings? Surely, everyone will immediately remember Saturn, whose bright and wide ring system is an integral part of the image of the planet.
But Saturn is not the only one that has a ring system. Formations of dust and ice also revolve around the other gas planets of the solar system: Jupiter, Uranus and Neptune. They were unknown to people for a long time, because... Before the invention of spacecraft and orbiting telescopes, astronomers could not see them. But with the development of technology, it was discovered that all ice giants in the solar system have rings. And today all these objects have been studied in detail.
In this article we will study in detail all the planets with rings in the solar system , who has them, and let's talk about their similarities and differences.
Saturn
The second largest and sixth most distant gas giant from the Sun. The planet is most recognizable among the objects of the Solar System precisely because of its bright ring formations. It is believed that they were formed from large satellites absorbed by Saturn at the dawn of their existence. The cores of the satellites were destroyed in the atmosphere of the giant, and particles of ice and dust formed such famous formations around its orbit.
In total, Saturn has 8 main ring formations. The first seven of them are named by letters of the Latin alphabet, and the last and most distant one is called Phoebus - in honor of one of the nicknames of the ancient Greek god Apollo.
Saturn's rings are the widest. Their diameter is more than 13 million km (the diameter of the last element of the system is the Phoebus formation). However, its thickness is small - from tens of meters to a kilometer. The total mass of the fragments from which they consist is 3*10 9 kg.
For example, element D is closest to the planet; it is located 67 thousand km from Saturn. Between themselves, the formations are separated by gaps and divisions, which received the names of famous astronomers. Elements of the system A and B located the largest division between themselves, 4700 km wide. This gap is named after the Italian astronomer Giovanni Cassini.
The Saturnian ring system is inclined to the orbital plane by 27°. When observed, this affects the visibility of the formation from Earth. During the giant's equinox, it is practically inaccessible for observation. Over the next 7 years, it gradually reveals itself, reaching its maximum visibility at the solstice. Over the next 7 years, visibility progressively worsens. In 1921, the “disappearance” of Saturn’s rings even led to panic among the inhabitants of the Earth. People believed that the formations around the planet had collapsed and their fragments were flying to our planet :).
Neptune
The planet is the smallest gas giant and the most distant in the solar system. Neptune's rings remained unknown to researchers for a long time. They were discovered only in 1989 by the American space probe Voyager 2. In total he has 5 ring formations. They were named in honor of the astronomers and mathematicians who took part in the discovery of Neptune.
The Halle formation is located closest to the surface of the planet (42,000 km). Next in sequence are Le Verrier, Lascelles, Arago and Adams. The latter has a radius of 63 thousand km and consists of 5 arcs: Courage, Freedom, Equality 1, Equality 2, Brotherhood.
In addition to the ice, dust and debris that are the main components of any ring formation, they have a high percentage of likely organic matter, which gives them their red color.
Jupiter
The planet has the most impressive dimensions. The Voyager 1 interplanetary probe confirmed the presence of rings around Jupiter, the fifth planet of the solar system. Galileo probe and
and the Hubble orbital observatory received additional information about them.
Jupiter's rings are thin and weak. The halo closest to the planet has a radius of 92 thousand km. It is the most massive and its thickness reaches 12.5 thousand km. This is followed by the subtle main one and two so-called “web” ones, named after the satellites of the planet that form them - Amalthea and Thebe. The total radius of the system is 226 thousand km.
Uranus
This pale blue “icy” planet is the seventh farthest from the Sun. Uranus has developed a ring system stronger than that of Neptune and Jupiter. It consists of 9 narrow main, 2 dust and 2 outer rings. The closest to the planet is the ζ(zeta) ring, whose radius is 37 thousand km. Further μ(mu) it is located from Uranus at a distance of 103 thousand km. The brightest formation is ε(epsilon). Its brightness is due to a dense layer of ice particles that reflect the most light in the system.
The composition includes the dimmer elements of the system in addition to ice and dust, an extremely dark substance that absorbs light. It is believed that this is organic matter irradiated by the planet’s magnetosphere. All elements of the uranium ring system occurred as a result of the collision of small satellites and the destruction of asteroids that entered the planet's atmosphere.
According to astronomers, solid-state planets, including the Earth, previously had ring formations. In tens of millions of years, a similar fate awaits Mars when the moon Phobos falls onto its surface under the force of tidal interaction.
Astronomer Eric Mamajek of the University of Rochester and his partner at the Leiden Observatory in Holland have discovered that the ring system of one of the exoplanets that transits the Sun-like star J1407 has proportions that are completely unimaginable from the point of view of our solar system. It is much larger and much heavier than Saturn's ring system. In general, these rings are the first to be discovered outside our system, and this happened in 2012.
Eric's colleague, Matthew Kenforty, from the Leiden Observatory, carried out an analysis and found that the discovered ring system consists of more than thirty rings, each of which has tens of millions of kilometers in diameter. In addition, gaps were found in the rings, which indicate that satellites (exomoons) may have formed here.
“The detail we see in the light curves is incredible. The transit eclipse of the star lasted for several weeks, but we were able to see changes over time periods of only tens of minutes. This is explained by changes in the microstructures in the rings. The star itself is too close to observe the rings with direct observations, but we were able to create a detailed model based on sudden changes in the brightness of starlight through the local exoplanet's ring system. If we could replace Saturn's rings with those of exoplanet J1407b (1SWASP J1407 b), they would be easily visible at night and would be many times larger than the full Moon,” says Kenworthy.
“This planet is much larger than Jupiter or Saturn, and its ring system is about 200 times larger than Saturn's. We can say that we are observing a super Saturn,” echoes colleague Mamayek.
Astronomers analyzed data on the star obtained by the SuperWASP project. This survey was designed to detect gas giants by the transit method (when an exoplanet passes across the disk of its star, if this event can be seen from Earth). In 2012, Mamajek and his colleagues at the University of Rochester reported the discovery of the young star J1407, as well as unusual eclipses. It was then proposed that these eclipses are caused by the presence of a forming protosatellite disk around a young giant planet or brown dwarf. Kenworthy then conducted fresh studies using adaptive optics and Doppler spectroscopy to estimate the mass of the ring-shaped object. After this, they were able to come to the conclusion that scientists are observing in the J1407 system a giant exoplanet (which has not yet been found) with a giant ring system, which is precisely responsible for the repeated decrease in the star’s brightness. After analyzing the light curve, it was possible to establish that the diameter of the rings is almost 120 million kilometers, which is more than 200 times the diameter of the Saturn system, and the mass of material that the rings of J1407b contain is approximately equal to the mass of the entire Earth.
Here's what Mamayek reports about how much material is contained in these disks and rings: “If we were to blow up the four main Galilean moons of Jupiter and scatter their material into rings in the orbit of the planet, then this ring would be so opaque, that for a distant observer who would look at the Sun during the passage of these rings across its disk, a strong multi-day eclipse would occur. In the case of J1407, we observe that the rings block as much as 95 percent of all light from this young star for many days. Thus, these rings contain a lot of material from which satellites can form.
In the data they examined, astronomers found at least one gap in the ring structure. One obvious explanation for this is the formation of a satellite in this area, which took all the building material and created a gap in the rings. Its mass may be within the range of that of Earth or Mars, and its orbital period around J1407b is about two years. Scientists expect that over the next few million years the rings will become less dense due to the formation of new satellites and will eventually disappear.
“The scientific community involved in the problems of planetary astronomy has for many decades put forward various theories about what kind of ring systems Jupiter and Saturn had on early stages their lives, which then formed into satellites. However, until we discovered this ring structure in 2012, no one had ever observed such phenomena before.”
Scientists estimate that the orbital period of the exoplanet J1407b with its ring system is about a decade. The exact mass is also difficult to determine, but the most likely range is approximately 10-40 Jupiter masses. Scientists strongly encourage amateur astronomers to also observe this star and record the events of its eclipse by an exoplanet. The results of such observations can be reported to the American Association of Variable Star Observers (AAVSO).
Image
An artist's view of the ring system around exoplanet 1SWASP J1407 b.
RINGS OF PLANETS, formations orbiting a planet in its equatorial plane and having the appearance of a disk. The rings of the planets are located at a certain distance from the planet and consist of a collection of small solid particles, representing an almost infinite number of small satellites of the planet. In the Solar System, all giant planets have rings; the terrestrial planets do not have rings. The most famous is the system of Saturn's rings (it was first observed by G. Galileo in 1610; H. Huygens in 1655 established that it was a system of rings). For other giant planets, the rings were discovered only in the 1970-80s (for Uranus - when it covered a star, for Jupiter and Neptune - when flying near the planets of the Voyager spacecraft).
Ring structure. The ring of Jupiter is located at a distance of 50 thousand km from the conventional boundary in the planet’s atmosphere (with a pressure of about 1 atmosphere) and has a width of about 1000 km. The ring is an area of relatively low density, filled predominantly with small silicate particles (less than 10 -5 m), giving the area an orangeish color. Toward and away from Jupiter, this region is continued by a diffuse nebula of a more or less homogeneous structure.
Saturn's rings have a much more complex structure. There are seven regions (zones) in them. Three main concentric zones: the outer ring A, the brightest middle ring B (these rings can be observed even with ordinary binoculars) and a rather transparent “crepe” inner ring C, which does not have a sharp boundary (Fig. 1). Rings A and B are separated by the so-called Cassini gap, about 4,700 km wide, while rings S and C are separated by the so-called Maxwell gap, about 270 km wide. The inner region of ring C closest to the planet is distinguished as ring D. At the outer boundary of ring A there is a very narrow ring F of an irregular shape, behind which there is ring G and the outermost, almost transparent ring E. The outer boundary of ring A is located at a distance of about 75 thousand km from the conventional boundary in the planet’s atmosphere (with a pressure of 1 atmosphere), the inner boundary of the C ring is at a distance of about 20 thousand km. Thus, the length of Saturn’s clearly distinguishable rings is about 55 thousand km, while their thickness does not exceed 3.5 km. The predominant size of ring particles is several centimeters, but there are also particles with a characteristic size of several micrometers and large fragments measuring units and tens of meters in size. Small particles participate in the formation of dusty plasma located above the plane of the B ring. The dusty plasma forms radial dark stripes (the so-called dark spokes), controlled by the planet’s magnetic field. The angular velocity of the “spokes” (as opposed to the Keplerian velocity of the ring particles) coincides with the angular velocity of the planet’s own rotation. The density of the rings is not great - stars shine through them. According to infrared spectrometry, particles in Saturn's rings are likely composed of water ice or ice-coated particles of other chemical compositions. The total mass of the ring particles roughly corresponds to a satellite with a diameter of about 200 km. In accordance with Kepler's laws, the speed of particle movement in the inner zone of the ring is greater than in the outer one.
Saturn's equator is inclined to the ecliptic plane at an angle of 27°, so at different points in the planet's orbit the rings are visible at different angles when observed from Earth. With the most favorable configuration, their entire width is visible - the so-called opening of the rings is observed. In another extreme case, the rings appear as a very thin strip, visible only with large telescopes. This occurs when the plane of the rings passes exactly through the center of the Sun and their lateral surface is unlit, or when the rings are facing the observer on Earth “edge-on”. The period of Saturn's revolution around the Sun and, accordingly, the full cycle of changes in the phases of the rings is about 29.5 years.
The rings of Uranus (Fig. 2) are very dark and narrow, consisting of particles that do not have an icy shell. By the end of 2008, Uranus had discovered 13 rings, designated by the letters of the Greek alphabet (α, β, γ, ...). The largest of these rings (ε) has an uneven width and shape. The plane of the rings of Uranus is almost perpendicular to the plane of the ecliptic.
Neptune's rings are formed by dark particles and consist of four narrow zones. They are distinguished by an even more irregular shape and variable density, so they appear to consist of individual “arches”. The two most distinctive arched rings are named after scientists J. C. Adams and W. Le Verrier, who predicted the existence of Neptune by calculating its orbit.
Formation of rings. The formation of ring systems around giant planets is a direct consequence of the laws of mechanics and resembles the process of planet formation. All rings are located inside the so-called Roche limit - the region in which a planetary satellite can be torn apart due to tidal forces. This effect prevents the consolidation of particles located near the planet and, accordingly, the formation of large satellites. The current configuration of the rings owes its origin to the influence of the gravitational attraction of the planet’s satellites located in the immediate vicinity (or even inside) of the ring structure and for this reason called “shepherds”. The particles of the rings, which themselves are small satellites, find themselves in resonances with the larger satellites of the planet (that is, the ratio of their period of revolution to the period of revolution of the satellite is expressed as a simple fraction - 1/2, 2/3, etc.). This leads to a disruption of the homogeneous structure of the rings, in particular to the formation of gaps inside them (for example, the Cassini gap in the rings of Saturn), which are similar in nature to “empty” regions (the so-called Kirkwood hatches) in the Main Asteroid Belt (see Asteroids). The same reasons cause the generation of density waves, the formation of a hierarchical structure of rings and their separation into thousands of thin spiral ringlets (ringlets), observed in the structure of the main rings of Saturn (Fig. 3).
The presence of satellites with very close orbits also leads to the effect of gravitational focusing and concentration of particles in the thin rings of Uranus and to the formation of particle clumps (arches) drifting in the azimuthal direction near the rings of Neptune. The mechanism for the formation of the arches is not fully understood, although one explanation is the presence of resonances of the particles of the rings with Neptune’s satellite Galatea, since the eccentricities and inclinations of the orbits of the particles and the satellite are practically the same. Resonances prevent particles from being distributed evenly along the orbit. Thus, the planetary rings represent a complex open system of particles in orbital motion and simultaneously experiencing chaotic interactions. As a result, a self-organization effect arises in the system, creating order in the configurations of the rings (primarily due to the emergence of collective processes and the presence of inelastic collisions of macroparticles in the disk system). The mechanism of self-organization is inherent in the system itself; the planet’s close satellites have an additional “stimulating” effect on the process.
There are two main hypotheses for the origin of planetary rings: 1) the formation of rings from particles of a protoplanetary cloud (from which satellites were formed outside the Roche limit); 2) the appearance of planetary rings as a result of the disintegration of an asteroid or comet that fell within the Roche limit. A typical example of the latter event is the ring of Jupiter. The second hypothesis is also supported by the estimated lifetime of the rings - about 0.5 billion years, which is significantly less than the age of the Solar System (about 4.5 billion years). Within the framework of this hypothesis, it must be assumed that the rings of planets periodically appear and disappear as a result of the gravitational capture of a small body by a planet and its subsequent destruction. Another argument confirming the decay hypothesis could be, for example, the predominantly icy particles of Saturn's rings. These particles have a high albedo, i.e., they are not covered with dark micrometeoric matter, as would have happened with relic rings during the existence of the Solar System.
Lit.: Planetary rings / Ed. R. Greenberg, A. Brahic. Tucson, 1984; Gorkavy N. N., Fridman A. M. Physics of planetary rings. M., 1994; Miner E., Wessen R., Cuzzi J. Planetary ring systems. IN.; N.Y., 2007.
