Saturn, the sixth planet from the Sun. The rings of Saturn are a system of flat concentric formations of ice and dust, located in the equatorial plane of the planet. The planet has seven main (A, B, C, D, E, F, G) and many small rings.
The opening of the rings of Saturn
1610 - Galileo Galilei was the first to see the rings of Saturn in his telescope at 20x magnification, but did not recognize them as rings.
1655 - Christian Huygens, a scientist from the Netherlands, was the first to recognize the ring in the strange protrusions that accompanied Saturn. But only 4 years later, convinced that he was right, he told from the pages of the book "System of Saturn" that Saturn "is surrounded by a thin, flat ring, not touching anywhere, inclined to the ecliptic."
1675 - the director of the Paris Observatory, Giovanni Domenico Cassini, discovered a black stripe inside the ring (later it was called the "Cassini division"). She cut it into two parts - they began to be called rings A and B. He was the first to make the assumption that the rings consist of separate particles.
The origin of the rings
Promotional video:
Now hypotheses began to appear one after another. For several centuries, the mysterious rings of Saturn have invariably attracted the attention of astronomers. The more perfect the telescopes became, the more complex the structure of the rings seemed. Nowadays - with the help of interplanetary probes that have been near Saturn - we know a lot about them. In addition to the main ones, astronomers have already counted more than 100 thousand separate rings surrounding the planet. They are different in their chemical composition and color. The origin of the rings still raises many questions. Researchers never cease to put forward all new hypotheses explaining the nature of the rings.
Hypotheses
In the 19th century, French astronomer Edouard Albert Roche hypothesized that one of Saturn's moons had come so close to the planet that it was torn apart by tidal forces, and its debris formed rings that now surround Saturn. Not a single satellite that has crossed the so-called "Roche limit" can survive; sooner or later it will disintegrate, forming another ring, which will later settle on the planet. Be that as it may, rings, according to the supporters of this hypothesis, are temporary. We are lucky to live at a time when several large planets are surrounded by them at once.
According to another hypothesis, the rings could have formed after the collision of one of Saturn's moons with a large meteorite. Many debris that littered the planet's surroundings after the collision became the material from which the rings were formed. Calculations have shown that their age is no more than 100 million years.
What rings are made of
We now know that Saturn's rings are 90–95% water ice. But the celestial bodies, which could serve as material for them, are at least half composed of various silicates and metals. Therefore, the rings of Saturn should also contain at least several tens of percent of these materials. Only new hypotheses can resolve this contradiction.
But what if the rings of Saturn, like the satellites closest to it, were formed due to the same catastrophe? This version was put forward in 2010 by the American astrophysicist Robin Kanup. He suggested that, in the distant past, another satellite as large as Titan revolved around Saturn. Its core consisted of silicates and iron, and a powerful ice shell covered it. Approaching the planet at a distance equal to the Roche limit, under the influence of tidal forces, he threw off this ice shell, and that, gradually disintegrating into ever smaller parts, began to circle around Saturn, forming numerous rings. As for the iron-stone core of the satellite, it collapsed on Saturn.
According to calculations, Saturn's rings once weighed thousands of times more than they do now. However, asteroids and comets, occasionally crashing into them, knocked out some of the material. It could have formed the inner satellites of Saturn - for example, Tethys. Meanwhile, silicates and metals contained in asteroids replenished the material of the rings - this is how those 5-10% of impurities that were found there appeared.
When did the rings form?
However, this hypothesis, like the others mentioned, has the same drawbacks. For example, after the destruction of a satellite, fragments of various sizes appear - from ice cubes to ice mountains stretching for tens of kilometers. In fact, none of the ice floes that formed the rings are no more than 10 meters long. It's another matter if the rings of Saturn appeared together with the planet! Then - because of the powerful counteraction of gravity - small pieces of ice would not be able to get lost even into lumps the size of a house. In addition, the destruction of the satellite is still an accident, and all the giant planets are surrounded by rings, therefore it is not very hard to believe in randomness. Many astronomers believe that the rings around the planets formed at the same time.
So, these rings are composed of matter that has survived since the emergence of the solar system? At that time, a huge disk of gas and dust revolved around the Sun, from the material of which the planets were born one after another. The remnants of the space blanks - all these ice and dust particles - now revolved among the newly minted planets, eventually rolling into clods of satellites. But they can arise only at some distance from the planet, otherwise they will quickly collapse. Therefore, for some time, fragments of a gas-dust disk remained nearby the giant planets, which subsequently formed separate rings.
Due to frequent collisions with each other, as well as the impact of powerful tidal forces, all these grains and lumps never made up a single satellite. If this version is correct, the material of the rings is constantly replenished with matter from the surface of Saturn's moons - otherwise the rings could evaporate in several hundred million years.
Detecting new rings
Astronomers, meanwhile, are discovering new rings of Saturn. So, some time ago, a previously unknown huge ring was noticed. In principle, the ring systems of giant planets are quite small compared to the planets themselves. According to astronomers, their radius does not exceed 5-10 radii of the planet. So, the radius of the largest known until recently rings of Saturn - rings E - did not exceed 10 radii of Saturn (its equatorial radius is 60 thousand km).
Observations have shown that the outer rings of Saturn are constantly fueled by dust escaping from the surface of its satellites after collisions with micrometeorites. It is from it that the ring, discovered only in 2009, consists. Its radius is from 100 to 200 radii of Saturn, and it is formed from dust thrown from the surface of Phoebe, the most distant and darkest satellite of the planet. They were able to discover the new ring thanks to the infrared radiation emanating from it. Unlike other rings of Saturn, it is located not in the equatorial plane of the planet, but in the plane of the orbit along which it revolves around the Sun. The angle between the two planes is about 27 °.
The density of this ring is only 20 particles per cubic kilometer (!). According to astronomer Anne Verbisker of the University of Virginia, who led the research, "the particles of the ring are so far apart that if you get inside it, you don't even notice it right away." Moreover, the particle size often does not exceed a few micrometers.
It seems that the dust particles that fly out of this ring are deposited on the surface of another satellite of Saturn, Iapetus, facing it. This explains the strange appearance of this moon. It is clearly divided into two halves, light and dark. According to experts, the height of the dust layer covering one of its sides ranges from 20 centimeters to several meters.
Recommended for viewing: "The greatest mystery of astronomers - how the rings of Saturn appeared."
