The period of revolution of Saturn around its axis. Saturn: the story of a ringed planet. Rotation and orbital characteristics of Saturn

This article is a message or report on Saturn, which sets out characteristic this planet of the solar system: basic astronomical data, the structure of the atmosphere and core, a description of the rings and satellites.

Astronomical data of Saturn

Maximum distance from the Sun (aphelion) 1.513 billion km (10.116 AU)
Minimum distance from the Sun (perihelion) 1.354 billion km (9.048 AU)
Equator diameter 120,540 km
The average temperature of the upper atmosphere-180º C
Period of revolution around the sun 29.458 Earth years
Period of revolution around the axis 10 h 34 min 13 s
Number of rings 8
Number of satellites 62

Description of the planet

This planet - a pale golden ball surrounded by the thinnest ring - got its name from the ancient Roman god of crops, the father of Jupiter. The sixth in the solar system and the second largest, Saturn revolves around our star at an average distance of 1.4 billion km, twice as far from the star as Jupiter. The substance of this celestial body, like Jupiter, Uranus and Neptune, has a low average density (0.69 g / cm 3), since it consists mainly of gases; however, the giant planet Saturn is about 95 times more massive than Earth.

Due to the large distance from the center of the solar system, its orbital period (i.e., the Saturnian year) is very long and is about 29.5 Earth. At the same time, Saturn's rotation around its axis occurs much faster than that of the Earth: one day here lasts only 10 hours and 34 minutes. The speed of movement of clouds over the equatorial zone of the planet is such that they complete a full revolution 26 minutes faster than clouds at higher latitudes; the reason for this is the enormous force (about 500 m / s) of the winds blowing in the upper atmosphere.

atmosphere and core

Saturn is enveloped in a dense, cloud-filled layer of gases. The basis of its atmosphere is helium and hydrogen; the clouds are composed mainly of water and ammonia crystals. Just like the closest neighbor in the solar system - Jupiter, in the visible atmospheric layers of this planet there are certain areas, painted in both darker and lighter colors (the so-called belts and zones, respectively); they are quite clearly distinguishable, although less contrasting than that of Jupiter. In addition, relatively stable atmospheric disturbances are also observed here - for example, the Great White Spot, which existed for several months and then revived about three decades later; giant oval formation the size of the Earth, located near north pole, has been named the Great Brown Spot.

An irregular ball reaching a diameter of about 120.5 thousand km (the atmosphere of the planet is highly prone to flattening at the poles, since rapid rotation contributes to its “squeezing” into the equatorial regions) consists of several layers. It is assumed that at least two layers of liquid hydrogen are hidden in its depths, and one of them, consisting of the so-called metallic hydrogen, can conduct electricity.

The core of Saturn is a huge sphere composed, apparently, of stones and ice. According to scientists, its size exceeds the core of Jupiter (about 30 thousand km): indirect evidence of this is a more active movement of atmospheric masses from the poles to the equator.

Rings

Since the planet's axis is very strongly - more than 63º - inclined to the plane of the orbit, earthly astronomers have an excellent opportunity to observe these amazing formations in the plan. It is believed that they were first seen by Galileo Galilei (1564-1642) in 1610, but due to the imperfection of the telescope, they were considered a chain of satellites; only half a century later, the Dutch scientist Huygens managed to find out that this is a ring that surrounds the planet and does not touch it anywhere.

Due to the movement of Saturn in its orbit, the rings slowly turn towards us, first one side, then the other; every 15 years they are edge-on to us, and then they cannot be seen even in the most powerful telescopes. At first it was believed that it was a huge monolith, but later studies disproved this theory. In particular, information received from spacecraft series "Pioneer" and "Voyager" in 1970-1980, testified: Saturn surrounds no less than seven rings, and the structure of each is very complex. The eighth ring - the Phoebe ring - with a diameter of more than 13 million km, was discovered in 2009. There is also an assumption about the presence of a system of rings in one of the satellites of Saturn - Rhea.

Apparently, the rings are the remnants of that pre-planetary cloud that gave birth to all the bodies of the solar system, and consist of small - from 1 mm to several meters - dust particles covered with ice. With an average thickness of 10 m to 10 km, their diameter is 270 thousand km. The three brightest are named A, B and C; unlike the D, E, F and G rings, which are narrower and dimmer, they are quite distinguishable from the Earth even with a weak telescope. Rings A and B are separated by the so-called Cassini gap (named after the Italian astronomer who lived in the 17th-18th centuries); a similar "hole" in the body of the ring A is called the Encke gap. In addition, the Cassini automatic station in early 2004 discovered that Saturn had a radiation belt inside the rings, which came as a complete surprise to scientists.

satellites

In addition to the billions of tiny moons that make up its rings, Saturn also has big amount satellites - 62. Their size and shape are very different: there are objects like Iapetus and Rhea (average diameters are 1,436 and 1,528 km, respectively), and there are small satellites such as Atlas (about 32 km) and Telesto (24 km) . With modern equipment in last years it became possible to discover many of the smallest satellites by space standards, the diameter of which is less than 10 km.

The largest satellite of Saturn is Titan, its diameter is 5,150 km and in the entire solar system it is second only to Jupiter's moon Ganymede. Titan is one of the most interesting satellites of Saturn: it is believed that the processes occurring in its atmosphere (85% nitrogen, about 12% argon and 3% methane) are similar to those that could be found on the young Earth billions of years ago. On January 14, 2005, the Huygens probe was launched to this planet, transmitting a lot of valuable scientific information.

Periods of revolution and radii of orbits in each of three groups Saturn's satellites - Tethys, Telesto and Calypso, Dione and Helena, Janus and Epimetheus - are the same. There are others Interesting Facts: for example, the Encke gap inside ring A arose due to the satellite Pan, whose orbit lies in the same plane, and the satellites Atlas and Prometheus, between whose orbits the ring F is located, do not allow its constituent particles to scatter in space (for this they received the nickname "moon - shepherds).

In addition to Saturn, other planets of the solar system also have rings: Jupiter, Uranus and Neptune.

The starry sky has always attracted romantics, poets, artists and lovers with its beauty. Since time immemorial, people have admired the scattering of stars and attributed to them special magical properties.

Ancient astrologers, for example, were able to draw a parallel between the date of birth of a person and the star that shone brightly at that moment. It was believed that it can influence not only the totality of the character traits of a newborn, but also his entire future fate. Stargazing helped farmers determine best date for sowing and harvesting. It can be said that much in the life of ancient people was subject to the influence of stars and planets, so it is not surprising that mankind has been trying to study the planets closest to the Earth for more than one century.

Many of them are currently quite well studied, but some can present scientists with many surprises. To such planets, astronomers, in the first place, include Saturn. A description of this gas giant can be found in any textbook on astronomy. However, scientists themselves believe that this is one of the most poorly understood planets, all the mysteries and secrets of which humanity is not even able to list yet.

Today you will receive the most detailed information about Saturn. The mass of the gas giant, its size, description and Comparative characteristics with the Earth - all this you can learn from this article. Perhaps you will hear some facts for the first time, and something will seem simply incredible to you.

Ancient conceptions of Saturn

Our ancestors could not accurately calculate the mass of Saturn and characterize it, but they definitely understood how majestic this planet was and even worshiped it. Historians believe that Saturn, which belongs to one of the five planets that are perfectly distinguishable from Earth with the naked eye, has been known to people for a very long time. It got its name in honor of the god of fertility and agriculture. This deity was highly revered among the Greeks and Romans, but in the future the attitude towards him changed slightly.

The fact is that the Greeks began to associate Saturn with Kronos. This titan was very bloodthirsty and even devoured his own children. Therefore, he was treated without due respect and with some apprehension. But the Romans revered Saturn very much and even considered him a god who gave humanity many of the knowledge necessary for life. It was the god of agriculture who taught ignorant people to build living quarters and save the grown crop until the next year. In gratitude to Saturn, the Romans held real holidays lasting several days. During this period, even slaves could forget about their insignificant position and fully feel like free people.

It is noteworthy that in many ancient cultures, Saturn, which scientists were able to characterize only after millennia, was associated with strong deities who confidently control the destinies of people in many worlds. Modern historians often wonder what ancient civilizations might have known about this giant planet much more than we do today. Perhaps other knowledge was available to them, and we just have to, throwing away dry statistical data, penetrate into the secrets of Saturn.

Brief description of the planet

In a few words, it is quite difficult to tell which planet Saturn really is. Therefore, in the current section, we will give the reader all the known data that will help to form some idea about this amazing celestial body.

Saturn is the sixth planet in our native solar system. Since it mainly consists of gases, it is classified as a gas giant. Jupiter is usually called the closest "relative" of Saturn, but besides it, Uranus and Neptune can also be added to this group. It is noteworthy that all gaseous planets can be proud of their rings, but only Saturn has them in such quantity that it allows you to see its majestic "belt" even from Earth. Modern astronomers rightly consider it the most beautiful and bewitching planet. After all, the rings of Saturn (what this magnificence consists of, we will tell in one of the following sections of the article) almost constantly change their color and each time their photo surprises with new shades. Therefore, the gas giant is one of the most recognizable among the other planets.

The mass of Saturn (5.68 × 10 26 kg) is extremely large compared to the Earth, we will talk about this a little later. But the diameter of the planet, which, according to the latest data, is more than one hundred and twenty thousand kilometers, confidently brings it to second place in the solar system. Only Jupiter, the leader in this list, can argue with Saturn.

The gas giant has its own atmosphere, magnetic fields and a huge number of satellites, which were gradually discovered by astronomers. Interestingly, the density of the planet is noticeably less than the density of water. Therefore, if your imagination allows you to imagine a huge pool filled with water, then be sure that Saturn will not drown in it. Like a huge inflatable ball, it will slowly slide over the surface.

Origin of the gas giant

Despite the fact that Saturn has been actively explored by spacecraft over the past decades, scientists still cannot confidently say exactly how the planet was formed. To date, two main hypotheses have been put forward, which have their followers and opponents.

The Sun and Saturn are often compared in composition. Indeed, they contain a large concentration of hydrogen, which allowed some scientists to hypothesize that our star and the planets of the solar system were formed at almost the same time. Massive gas accumulations became the ancestors of Saturn and the Sun. However, none of the supporters of this theory can explain why, if I may say so, a planet was formed from the source material in one case, and a star in the other. The differences in their composition, too, no one can yet give a worthy explanation.

According to the second hypothesis, the process of formation of Saturn lasted hundreds of millions of years. Initially, there was the formation of solid particles, which gradually reached the mass of our Earth. However, at some point the planet lost a large number gas and at the second stage it actively increased it from outer space by means of gravity.

Scientists hope that in the future they will be able to discover the secret of the formation of Saturn, but before that they still have many decades of waiting. After all, only the Cassini apparatus, which worked in its orbit for a long thirteen years, managed to get as close as possible to the planet. This autumn, he completed his mission, collecting for observers a huge amount of data that has yet to be processed.

planet orbit

Saturn and the Sun are separated by almost one and a half billion kilometers, so the planet does not get much light and heat from our main luminary. It is noteworthy that the gas giant rotates around the Sun in a slightly elongated orbit. However, in recent years, scientists have argued that almost all planets do this. Saturn makes a complete revolution in almost thirty years.

The planet spins extremely fast around its axis, it takes about ten Earth hours for a revolution. If we lived on Saturn, that is how long a day would last. Interestingly, scientists tried to calculate the full rotation of the planet around its axis several times. During this time, an error of approximately six minutes occurred, which is considered quite impressive in the framework of science. Some scientists attribute it to the inaccuracy of instruments, while others argue that long years our native Earth began to rotate more slowly, which allowed errors to form.

Planet structure

Since the size of Saturn is often compared with Jupiter, it is not surprising that the structures of these planets are very similar to each other. Scientists conditionally divide the gas giant into three layers, the center of which is a rocky core. It has a high density and is at least ten times more massive than the Earth's core. The second layer, where it is located, is liquid metallic hydrogen. Its thickness is approximately fourteen and a half thousand kilometers. The outer layer of the planet is molecular hydrogen, the thickness of this layer is measured in eighteen and a half thousand kilometers.

Scientists, studying the planet, found out one interesting fact - it emits two and a half times more radiation into outer space than it receives from the star. They tried to find a definite explanation for this phenomenon, drawing a parallel with Jupiter. However, until now it remains another mystery of the planet, because the size of Saturn is smaller than its "brother", radiating in the world much more modest amounts of radiation. Therefore, today such activity of the planet is explained by the friction of helium flows. But how viable this theory, scientists cannot say.

Planet Saturn: composition of the atmosphere

If you observe the planet through a telescope, it becomes noticeable that the color of Saturn has a somewhat muted pale orange hue. On its surface, stripe-like formations can be noted, which are often formed into bizarre shapes. However, they are not static and quickly transform.

When we talk about gaseous planets, it is rather difficult for the reader to understand exactly how the difference between the conditional surface and the atmosphere can be determined. Scientists also faced a similar problem, so it was decided to determine a certain starting point. It is in it that the temperature begins to drop, and here astronomers draw an invisible boundary.

Saturn's atmosphere is almost ninety-six percent hydrogen. Of the constituent gases, I would also like to name helium, it is present in an amount of three percent. The remaining one percent is divided among themselves by ammonia, methane and other substances. For all living organisms known to us, the atmosphere of the planet is destructive.

The thickness of the atmospheric layer is close to sixty kilometers. Surprisingly, Saturn, like Jupiter, is often referred to as the "planet of storms." Of course, by the standards of Jupiter, they are insignificant. But for earthlings, a wind of almost two thousand kilometers per hour will seem like the real end of the world. Such storms occur on Saturn quite often, sometimes scientists notice formations in the atmosphere that resemble our hurricanes. In a telescope, they look like vast white spots, and hurricanes are extremely rare. Therefore, observing them is considered a great success for astronomers.

Rings of Saturn

The color of Saturn and its rings is approximately the same, although this "belt" sets a huge number of problems for scientists that they are not yet able to solve. It is especially difficult to answer questions about the origin and age of this splendor. To date, the scientific community has put forward several hypotheses on this topic, which no one can yet prove or disprove.

First of all, many young astronomers are interested in what the rings of Saturn are made of. Scientists can answer this question quite accurately. The structure of the rings is very heterogeneous, it consists of billions of particles that move at great speed. The diameter of these particles ranges from one centimeter to ten meters. They are ninety-eight percent ice. The remaining two percent are represented by various impurities.

Despite the impressive picture that the rings of Saturn present, they are very thin. Their thickness, on average, does not even reach a kilometer, while their diameter reaches two hundred and fifty thousand kilometers.

For simplicity, the rings of the planet are usually called one of the letters of the Latin alphabet, three rings are considered the most noticeable. But the second is considered the most striking and beautiful.

Ring formation: theories and hypotheses

Since ancient times, people have puzzled over exactly how the rings of Saturn were formed. Initially, a theory was put forward about the simultaneous formation of the planet and its rings. However, later this version was refuted, because scientists were struck by the purity of the ice, of which the “belt” of Saturn consists. If the rings had the same age as the planet, then their particles would be covered with a layer that can be compared to dirt. Since this did not happen, the scientific community had to look for other explanations.

The theory about the exploded satellite of Saturn is considered traditional. According to this statement, approximately four billion years ago, one of the planet's satellites came too close to it. According to scientists, its diameter could reach up to three hundred kilometers. Under the influence of the tidal force, it was torn into billions of particles that formed the rings of Saturn. The version about the collision of two satellites is also considered. Such a theory seems the most plausible, but recent data make it possible to determine the age of the rings as one hundred million years.

Surprisingly, the particles of the rings constantly collide with each other, form into new formations, and thus make it difficult to study them. Modern scientists are still unable to solve the mystery of the formation of the "belt" of Saturn, which has added to the list of mysteries of this planet.

Moons of Saturn

The gas giant has a huge number of satellites. Forty percent of all known systems revolve around it. To date, sixty-three moons of Saturn have been discovered, and many of them present no less surprises than the planet itself.

The size of satellites ranges from three hundred kilometers to more than five thousand kilometers in diameter. The easiest way for astronomers to discover large moons, most of them were able to describe in the late eighties of the eighteenth century. It was then that Titan, Rhea, Enceladus and Iapetus were discovered. These moons are still of great interest to scientists and are closely studied by them.

Interestingly, all the moons of Saturn are very different from each other. They are united by the fact that they are always turned to the planet with only one side and rotate almost synchronously. The three moons of greatest interest to astronomers are:

Titanium.
Enceladus.

Titan is the second largest in the solar system. It is not surprising that it is second only to one of the satellites of Titan, half the size of the Moon, and the size is comparable to Mercury and even exceeds it. Interestingly, the composition of this giant moon of Saturn contributed to the formation of the atmosphere. In addition, there is liquid on it, which puts Titan on a par with the Earth. Some scientists even suggest that there may be some form of life on the moon's surface. Of course, it will be significantly different from the earth, because the atmosphere of Titan consists of nitrogen, methane and ethane, and on its surface you can see lakes of methane and islands with a bizarre relief formed by liquid nitrogen.

Enceladus is no less amazing companion Saturn. Scientists call it the brightest celestial body in the solar system because of its surface, completely covered with an ice crust. Scientists are sure that under this layer of ice lies a real ocean, in which living organisms may well exist.

Rhea recently surprised astronomers. After numerous shots, they were able to see several thin rings around her. It is too early to talk about their composition and size, but this discovery was shocking, because previously it was not even assumed that rings could rotate around the satellite.

Saturn and Earth: a comparative analysis of these two planets

Comparisons between Saturn and Earth are rarely made by scientists. These celestial bodies are too different to compare them with each other. But today we decided to expand the reader's horizons a little and still look at these planets with a fresh look. Is there anything in common between them?

First of all, it comes to mind to compare the mass of Saturn and the Earth, this difference will be incredible: the gas giant is ninety-five times larger than our planet. In size, it exceeds the Earth nine and a half times. Therefore, in its volume, our planet can fit more than seven hundred times.

Interestingly, the gravity on Saturn will be ninety-two percent of the earth's gravity. If we assume that a person weighing one hundred kilograms is transferred to Saturn, then his weight will decrease to ninety-two kilograms.

Every student knows that the earth's axis has a certain angle of inclination relative to the sun. This allows the seasons to change each other, and people enjoy all the beauties of nature. Surprisingly, Saturn's axis has a similar tilt. Therefore, the planet can also observe the change of seasons. However, they do not have a pronounced character and it is quite difficult to trace them.

Like the Earth, Saturn has its own magnetic field, and recently scientists have witnessed a real aurora that spilled over the conditional surface of the planet. It pleased with the duration of the glow and bright purple hues.

Even from our small comparative analysis it is clear that both planets, despite the incredible differences, have something that unites them. Perhaps this makes scientists constantly turn their gaze towards Saturn. However, some of them laughingly say that if it were possible to look at both planets side by side, then the Earth would look like a coin, and Saturn would look like an inflated basketball.

Studying the gas giant that is Saturn is a process that puzzles scientists all over the world. More than once they sent probes and various apparatuses to him. Since the last mission was completed this year, the next one is scheduled only for 2020. However, now no one can say whether it will take place. For several years, negotiations have been underway on Russia's participation in this large-scale project. According to preliminary calculations, the new device will take about nine years to get into the orbit of Saturn, and another four years to study the planet and its largest satellite. Based on the foregoing, one can be sure that the disclosure of all the secrets of the planet of storms is a matter of the future. Perhaps you, our readers today, will also take part in this.

Saturn is the sixth planet from the Sun and the second largest planet in the solar system after Jupiter..
Saturn is 1.4 billion km (9.5 AU) from the Sun
Gas giant Saturn, consists of hydrogen with helium impurities and traces of water, methane, ammonia, heavy elements.
A day (a full rotation around its axis) on Saturn lasts 10.7 hours. A year (a complete revolution around the Sun) is 29 Earth years.
There are 62 moons around Saturn. Titan is the largest of them, its size is slightly inferior to Jupiter's moon Ganymede. Titan is larger than Mercury and has the only one among the satellites of the solar system dense atmosphere.
The wind speed on Saturn can reach 1800 km/h in places, which is much more than on Jupiter.
Saturn is the owner of the most visible and exciting rings among the gas giant planets.. Seven thin rings have dividing stripes. The rings are 250,000 km in diameter and less than 1 km thick. By composition, the rings of Saturn are 93% ice with minor impurities, which may include copolymers formed under the action of solar radiation and silicates, and 7% carbon.
Five missions have been sent to Saturn. Since 2004, Saturn, its moons and rings have been studied by the automatic interplanetary station Cassini. Cassini carried the European probe Huygens, which landed on Titan for the first time on January 14, 2005.
There is no life on Saturn as we know it. However, some of Saturn's moons have conditions that can support life.
As a planet in the solar system, Saturn has been known since the 1600s. Saturn is one of the five planets in the solar system that are easily visible. naked eye from Earth. To observe the rings of Saturn, you need a telescope with a diameter of at least 15 mm.

The universe is full of mysteries, as evidenced by interesting facts about the planet Saturn- a celestial body named after the longtime lord of the titans - Kronos.

The planet is shaped like an oblate ball.. Saturn acquired this shape as a result of rapid rotation around its axis. A day here lasts only 10.7 hours. Due to such intense rotation, the planet flattens itself.
The celestial body has a huge number of satellites (63). Scientists say that some of them have the necessary conditions for life.
Saturn has a developed system of rings, each of which has a bright and dark side.. However, the inhabitants of the Earth have the ability to see an exceptionally bright side. From our planet, the rings seem to disappear from time to time. This is due to the fact that only the edges of the rings are visible under the slope. According to modern theories, the rings were formed as a result of the destruction of Saturn's moons.
If you fantasize that the Sun is the size of a front door, then Saturn will resemble a basketball.. In this case, the Earth will be the size of an ordinary coin.
The planet is mostly made up of helium and hydrogen gases.. It has almost no hard surface.
If you put Saturn in water, he can float on it like a ball.. This is possible, since the density of the planet is 2 times less than that of water.
All rings have names that correspond to the letters of the Latin alphabet. They received their names in the order in which they were discovered.
Scientists around the world are actively studying Saturn. So far, 5 missions have been there. The first spacecraft visited this site in 1979. Since 2004, the study of the features of a celestial body has been carried out using a spacecraft called Cassini.
40% of all satellites in the universe revolve around Saturn. Among them there are both regular and irregular satellites. The orbits of the former are quite close to the planet, the rest are located far away. They were captured recently. Phoebe's moon is the farthest from the planet.
Astronomers put forward a hypothesis according to which Saturn influenced the structure of the solar system. Due to the action of its gravity, the planet managed to throw aside Uranus and Neptune. However, so far this is only an assumption for which evidence needs to be found.
The pressure of the atmosphere of the planet Saturn exceeds the earth's by 3 million times. At this gas planet, hydrogen is compressed into a liquid and then a solid state. If a person gets there, he will immediately be flattened by the pressure of the atmosphere.
The planet has northern lights. Managed to take it off spaceship near the north pole. A similar phenomenon could not be detected on any other planet.
Bad weather constantly rages on Saturn. There is a strong wind blowing, which sometimes turns into a hurricane. Local hurricanes are similar in their flow to the earth. Only they appear much more often. During hurricanes, giant spots are formed that resemble funnels. They can be seen from space.
Saturn is considered the most beautiful planet. The beauty of Saturn is provided by the delicate blue color of the surface, bright rings. By the way see this heavenly body possible from Earth without any optical instruments. The most bright Star in the sky - this is Saturn.
The planet radiates 2 times more energy than it receives from the Sun. Due to the remoteness of the location, very little flow reaches Saturn. solar energy. It is 91 times less than the Earth receives. At the lower boundary of the planet's clouds, the air temperature is only 150K. According to scientific hypotheses, the source of internal energy can be the energy released as a result of the gravitational differentiation of helium.

Saturn is the sixth planet from the Sun and the second largest planet in the solar system after Jupiter. Saturn, as well as Jupiter, Uranus and Neptune, are classified as gas giants. Saturn is named after the Roman god of agriculture.

Saturn is mostly made up of hydrogen, with some helium and traces of water, methane, ammonia, and heavy elements. The inner region is a small core of iron, nickel and ice, covered with a thin layer of metallic hydrogen and a gaseous outer layer. The outer atmosphere of the planet appears to be calm and homogeneous from space, although sometimes long-term formations appear on it. The wind speed on Saturn can reach 1800 km/h in places, which is much more than on Jupiter. Saturn has a planetary magnetic field, which occupies an intermediate position in strength between the Earth's magnetic field and the powerful field of Jupiter. Saturn's magnetic field extends 1,000,000 kilometers in the direction of the Sun. shock wave was recorded by Voyager 1 at a distance of 26.2 radii of Saturn from the planet itself, the magnetopause is located at a distance of 22.9 radii.

Saturn has a prominent ring system, consisting mainly of ice particles, a smaller amount of heavy elements and dust. There are 62 known planets revolving around the planet. this moment satellite. Titan is the largest of them, as well as the second largest satellite in the solar system (after the satellite of Jupiter, Ganymede), which is larger than Mercury and has the only dense atmosphere among the satellites of the solar system.

Currently orbiting Saturn is the automatic interplanetary station Cassini, launched in 1997 and reaching the Saturn system in 2004, whose task is to study the structure of the rings, as well as the dynamics of the atmosphere and magnetosphere of Saturn.

Saturn among the planets of the solar system

Saturn belongs to the type of gas planets: it consists mainly of gases and does not have a solid surface. The equatorial radius of the planet is 60,300 km, the polar radius is 54,400 km; Of all the planets in the solar system, Saturn has the most compression. The mass of the planet is 95 times the mass of the Earth, but the average density of Saturn is only 0.69 g / cm2, which makes it the only planet in the solar system whose average density is less than that of water. Therefore, although the masses of Jupiter and Saturn differ by more than 3 times, their equatorial diameter differs only by 19%. The density of other gas giants is much higher (1.27-1.64 g/cm2). Acceleration free fall at the equator is 10.44 m/s2, which is comparable to the values of the Earth and Neptune, but much less than that of Jupiter.

The average distance between Saturn and the Sun is 1430 million km (9.58 AU). moving with average speed At 9.69 km/s, Saturn orbits the Sun in 10,759 days (approximately 29.5 years). The distance from Saturn to the Earth varies from 1195 (8.0 AU) to 1660 (11.1 AU) million km, the average distance during their opposition is about 1280 million km. Saturn and Jupiter are in an almost exact 2:5 resonance. Since the eccentricity of Saturn's orbit is 0.056, the difference between the distance to the Sun at perihelion and aphelion is 162 million km.

The characteristic objects of Saturn's atmosphere visible during observations rotate with different speed depending on latitude. As in the case of Jupiter, there are several groups of such objects. The so-called "Zone 1" has a rotation period of 10 h 14 min 00 s (i.e. the rate is 844.3°/day). It extends from the northern edge of the southern equatorial belt to the southern edge of the northern equatorial belt. At all other latitudes of Saturn that make up "Zone 2", the rotation period was originally estimated at 10 h 39 min 24 s (speed 810.76 ° / day). Subsequently, the data were revised: a new estimate was given - 10 hours, 34 minutes and 13 seconds. "Zone 3", the existence of which is assumed on the basis of observations of the planet's radio emission during the flight of Voyager 1, has a rotation period of 10 h 39 min 22.5 s (speed 810.8 ° / day).

The value of 10 hours, 34 minutes and 13 seconds is taken as the duration of Saturn's rotation around the axis. The exact value of the period of rotation of the inner parts of the planet remains difficult to measure. When the Cassini lander reached Saturn in 2004, it was found that, according to observations of radio emission, the rotation duration of the internal parts significantly exceeds the rotation period in "Zone 1" and "Zone 2" and is approximately 10 h 45 min 45 s (± 36 s) .

In March 2007, it was found that the rotation of Saturn's radio emission pattern is generated by convection flows in the plasma disk, which depend not only on the rotation of the planet, but also on other factors. It was also reported that the fluctuation of the period of rotation of the radiation pattern is associated with the activity of the geyser on Saturn's moon - Enceladus. Charged particles of water vapor in the orbit of the planet lead to distortion magnetic field and, as a consequence, radio emission patterns. The discovered picture gave rise to the opinion that today there is no correct method for determining the rotation speed of the planet's core at all.

Origin

The origin of Saturn (as well as Jupiter) is explained by two main hypotheses. According to the “contraction” hypothesis, the composition of Saturn, similar to the Sun (a large proportion of hydrogen), and, as a result, the low density can be explained by the fact that during the formation of planets in the early stages of the development of the Solar System, massive “clumps” formed in the gas and dust disk, which gave the beginning of the planets, that is, the Sun and the planets formed in a similar way. However, this hypothesis cannot explain the differences in the composition of Saturn and the Sun.

The "accretion" hypothesis states that the process of Saturn's formation took place in two stages. First, for 200 million years, there was a process of formation of solid dense bodies, like planets. terrestrial group. During this stage, part of the gas dissipated from the region of Jupiter and Saturn, which then affected the difference in chemical composition Saturn and Sun. Then the second stage began, when the largest bodies reached twice the mass of the Earth. For several hundred thousand years, the process of gas accretion onto these bodies from the primary protoplanetary cloud continued. At the second stage, the temperature of the outer layers of Saturn reached 2000 °C.

Atmosphere and structure

Aurora borealis over Saturn's north pole. The auroras are colored blue, and the clouds below are red. Directly below the auroras, a previously discovered hexagonal cloud is visible.

Saturn's upper atmosphere is made up of 96.3% hydrogen (by volume) and 3.25% helium (compared to 10% in Jupiter's atmosphere). There are impurities of methane, ammonia, phosphine, ethane and some other gases. Ammonia clouds in the upper part of the atmosphere are more powerful than those of Jupiter. Clouds in the lower atmosphere are composed of ammonium hydrosulfide (NH4SH) or water.

According to the Voyagers, strong winds blow on Saturn, the devices recorded air speeds of 500 m / s. Winds blow mainly in an easterly direction axial rotation). Their strength weakens with distance from the equator; as we move away from the equator, westerly atmospheric currents also appear. A number of data indicate that the circulation of the atmosphere occurs not only in the upper cloud layer, but also at a depth of at least 2,000 km. In addition, Voyager 2 measurements showed that the winds in the southern and northern hemispheres are symmetrical about the equator. There is an assumption that symmetrical flows are somehow connected under the layer of the visible atmosphere.

In the atmosphere of Saturn, stable formations sometimes appear, which are super-powerful hurricanes. Similar objects are observed on other gas planets of the solar system (see the Great Red Spot on Jupiter, the Great Dark Spot on Neptune). The giant "Great White Oval" appears on Saturn about once every 30 years, the last time it was observed in 1990 (smaller hurricanes form more often).

On November 12, 2008, Cassini's cameras took infrared images of Saturn's north pole. On them, the researchers found auroras, the likes of which have never been observed in the solar system. Also, these auroras were observed in the ultraviolet and visible ranges. Auroras are bright continuous oval rings surrounding the planet's pole. The rings are located at a latitude, as a rule, at 70-80 °. The southern rings are located at an average latitude of 75 ± 1°, while the northern ones are approximately 1.5° closer to the pole, which is due to the fact that the magnetic field is somewhat stronger in the northern hemisphere. Sometimes the rings become spiral instead of oval.

Unlike Jupiter, Saturn's auroras are not related to the uneven rotation of the plasma sheet in the outer parts of the planet's magnetosphere. Presumably, they arise due to magnetic reconnection under the influence of the solar wind. The shape and appearance of Saturn's auroras change greatly over time. Their location and brightness are strongly related to the pressure of the solar wind: the greater it is, the brighter the aurora and closer to the pole. The average power of the aurora is 50 GW in the range of 80-170 nm (ultraviolet) and 150-300 GW in the range of 3-4 microns (infrared).

On December 28, 2010, Cassini photographed a storm resembling cigarette smoke. Another, especially powerful storm, was recorded on May 20, 2011.

Hexagonal formation at the north pole

Hexagonal atmospheric formation at Saturn's north pole

Clouds at the north pole of Saturn form a hexagon - a giant hexagon. It was first discovered during Voyager's flybys of Saturn in the 1980s, and has never been seen anywhere else in the solar system. The hexagon is located at a latitude of 78°, and each side is approximately 13,800 km, that is, more than the diameter of the Earth. Its rotation period is 10 hours 39 minutes. If Saturn's south pole, with its spinning hurricane, doesn't seem odd, then the north pole might be a lot more unusual. This period coincides with the period of change in the intensity of radio emission, which in turn is taken equal to the period of rotation of the inner part of Saturn.

The strange structure of the clouds is shown in an infrared image taken by the Saturn-orbiting Cassini spacecraft in October 2006. The images show that the hexagon has remained stable all 20 years after Voyager's flight. Films showing Saturn's north pole show that the clouds retain their hexagonal pattern as they rotate. Individual clouds on Earth may be shaped like a hexagon, but unlike them, the cloud system on Saturn has six well-defined sides of almost equal length. Four Earths can fit inside this hexagon. It is assumed that there is a significant uneven cloudiness in the hexagon area. Areas in which there is practically no cloudiness have a height of up to 75 km.

There is no complete explanation of this phenomenon yet, but scientists managed to conduct an experiment that quite accurately modeled this atmospheric structure. The researchers placed a 30-liter water bottle on a rotating apparatus, with small rings placed inside that rotated faster than the container. The greater the speed of the ring, the more the shape of the vortex, which was formed during the total rotation of the elements of the installation, differed from the circular one. During the experiment, a vortex in the form of a hexagon was also obtained.

Internal structure

The internal structure of Saturn

In the depths of Saturn's atmosphere, pressure and temperature increase, and hydrogen passes into a liquid state, but this transition is gradual. At a depth of about 30 thousand km, hydrogen becomes metallic (and the pressure reaches about 3 million atmospheres). The circulation of electric currents in metallic hydrogen creates a magnetic field (much less powerful than that of Jupiter). At the center of the planet is a massive core of heavy materials - rock, iron and, presumably, ice. Its mass is approximately 9 to 22 Earth masses. The temperature of the core reaches 11,700 °C, and the energy that it radiates into space is 2.5 times the energy that Saturn receives from the Sun. A significant part of this energy is generated due to the Kelvin-Heimholtz mechanism, which lies in the fact that when the temperature of the planet drops, the pressure in it also drops. As a result, it contracts, and the potential energy of its substance is converted into heat. However, it was shown that this mechanism cannot be the only source planetary energy. It is assumed that additional part heat is created due to condensation and subsequent fall of helium droplets through a layer of hydrogen (less dense than drops) deep into the nucleus. The result is a transition potential energy these drops into the heat. The core region is estimated to be approximately 25,000 km in diameter.

A magnetic field

Structure of Saturn's magnetosphere

Saturn's magnetosphere was discovered by the Pioneer 11 spacecraft in 1979. It is second only to Jupiter's magnetosphere in size. The magnetopause, the boundary between Saturn's magnetosphere and the solar wind, is located at a distance of about 20 Saturn radii from its center, and the magnetotail extends hundreds of radii. Saturn's magnetosphere is filled with plasma produced by the planet and its moons. Among the satellites, Enceladus plays the greatest role, the geysers of which emit about 300-600 kg of water vapor every second, part of which is ionized by Saturn's magnetic field.

The interaction between Saturn's magnetosphere and the solar wind generates bright aurora ovals around the planet's poles, visible in visible, ultraviolet and infrared light. The magnetic field of Saturn, like that of Jupiter, is created due to the dynamo effect during the circulation of metallic hydrogen in the outer core. The magnetic field is almost dipole, just like the Earth's, with north and south magnetic poles. The north magnetic pole is in the northern hemisphere, and the south is in the south, unlike the Earth, where the location of the geographic poles is opposite to the location of the magnetic ones. The magnitude of the magnetic field at Saturn's equator is 21 μT (0.21 G), which corresponds to a dipole magnetic moment of about 4.6? 10 18 T m3. Saturn's magnetic dipole is tightly coupled to its axis of rotation, so the magnetic field is very asymmetric. The dipole is somewhat shifted along Saturn's axis of rotation toward the north pole.

Saturn's internal magnetic field deflects the solar wind away from the planet's surface, preventing it from interacting with the atmosphere, and creates a region called the magnetosphere filled with a very different kind of plasma than solar wind plasma. Saturn's magnetosphere is the second largest magnetosphere in the solar system, the largest is Jupiter's magnetosphere. As in the Earth's magnetosphere, the boundary between the solar wind and the magnetosphere is called the magnetopause. The distance from the magnetopause to the center of the planet (along the straight line Sun - Saturn) varies from 16 to 27 Rs (Rs = 60330 km - the equatorial radius of Saturn). The distance depends on the pressure of the solar wind, which depends on solar activity. The average distance to the magnetopause is 22 Rs. On the other side of the planet, the solar wind stretches Saturn's magnetic field into a long magnetic tail.

Saturn exploration

Saturn is one of the five planets in the solar system that are easily visible to the naked eye from Earth. At its maximum, the brightness of Saturn exceeds the first magnitude. To observe the rings of Saturn, you need a telescope with a diameter of at least 15 mm. With an instrument aperture of 100 mm, a darker polar cap, a dark stripe near the tropic and a shadow of the rings on the planet are visible. And at 150-200 mm, four to five bands of clouds in the atmosphere and inhomogeneities in them will become noticeable, but their contrast will be noticeably less than that of Jupiter.

View of Saturn through a modern telescope (left) and through a telescope from the time of Galileo (right)

Observing Saturn for the first time through a telescope in 1609-1610, Galileo Galilei noticed that Saturn does not look like a single celestial body, but like three bodies that almost touch each other, and suggested that these are two large "companions" (satellites) of Saturn. Two years later, Galileo repeated his observations and, to his amazement, found no satellites.

In 1659, Huygens, using a more powerful telescope, found out that the "companions" are actually a thin flat ring that encircles the planet and does not touch it. Huygens also discovered Saturn's largest moon, Titan. Since 1675, Cassini has been studying the planet. He noticed that the ring consists of two rings separated by a clearly visible gap - the Cassini gap, and discovered several more large satellites of Saturn: Iapetus, Tethys, Dione and Rhea.

In the future, there were no significant discoveries until 1789, when W. Herschel discovered two more satellites - Mimas and Enceladus. Then a group of British astronomers discovered the Hyperion satellite, with a shape very different from spherical, in orbital resonance with Titan. In 1899, William Pickering discovered Phoebe, which belongs to the class of irregular satellites and does not rotate synchronously with Saturn like most satellites. The period of its revolution around the planet is more than 500 days, while the circulation goes in the opposite direction. In 1944, Gerard Kuiper discovered the presence of a powerful atmosphere on another satellite, Titan. This phenomenon is unique for a satellite in the solar system.

In the 1990s, Saturn, its moons and rings were repeatedly studied by the Hubble Space Telescope. Long-term observations have provided a lot of new information that was not available to Pioneer 11 and Voyagers during their single flyby of the planet. Several satellites of Saturn were also discovered, and the maximum thickness of its rings was determined. During measurements carried out on November 20-21, 1995, their detailed structure was determined. During the period of maximum inclination of the rings in 2003, 30 images of the planet were obtained in various wavelength ranges, which at that time gave the best spectrum coverage in the entire history of observations. These images allowed scientists to better understand the dynamic processes occurring in the atmosphere and create models of the seasonal behavior of the atmosphere. Also, large-scale observations of Saturn were carried out by the Southern European Observatory in the period from 2000 to 2003. Several small, irregularly shaped moons have been discovered.

Research using spacecraft

Solar eclipse by Saturn on September 15, 2006. Photo of the Cassini interplanetary station from a distance of 2.2 million km

In 1979, the automatic interplanetary station (AMS) of the United States "Pioneer-11" for the first time in history flew near Saturn. The study of the planet began on August 2, 1979. After the final approach, the device made a flight in the plane of the rings of Saturn on September 1, 1979. The flight took place at an altitude of 20,000 km above the maximum cloud height of the planet. Images of the planet and some of its satellites were obtained, but their resolution was not enough to see the details of the surface. Also, due to the low illumination of Saturn by the Sun, the images were too dim. The apparatus also studied the rings. Among the discoveries was the discovery of a thin F ring. In addition, it was found that many areas visible from Earth as bright were visible from Pioneer 11 as dark, and vice versa. The device also measured the temperature of Titan. Exploration of the planet continued until September 15, after which the apparatus flew to the more outer parts of the solar system.

In 1980-1981, Pioneer 11 was also followed by the American spacecraft Voyager 1 and Voyager 2. Voyager 1 made its closest approach to the planet on November 13, 1980, but its exploration of Saturn began three months earlier. During the passage, a number of photographs were taken in high resolution. It was possible to obtain an image of the satellites: Titan, Mimas, Enceladus, Tethys, Dione, Rhea. At the same time, the device flew near Titan at a distance of only 6500 km, which made it possible to collect data on its atmosphere and temperature. It was found that the atmosphere of Titan is so dense that it does not transmit enough light in the visible range, so photographs of the details of its surface could not be obtained. After that, the device left the plane of the ecliptic of the solar system to photograph Saturn from the pole.

Saturn and its satellites - Titan, Janus, Mimas and Prometheus - against the background of the rings of Saturn, visible from the edge and disk of the giant planet

A year later, on August 25, 1981, Voyager 2 approached Saturn. During its flight, the device made a study of the planet's atmosphere using radar. Data were obtained on the temperature and density of the atmosphere. About 16,000 photographs with observations were sent to Earth. Unfortunately, during the flights, the camera rotation system jammed for several days, and some of the necessary images could not be obtained. Then the device, using the force of gravity of Saturn, turned around and flew towards Uranus. Also, these devices for the first time discovered the magnetic field of Saturn and explored its magnetosphere, observed storms in the atmosphere of Saturn, obtained detailed images of the structure of the rings and found out their composition. The Maxwell gap and the Keeler gap in the rings were discovered. In addition, several new satellites of the planet were discovered near the rings.

In 1997, the Cassini-Huygens AMS was launched to Saturn, which, after 7 years of flight on July 1, 2004, reached the Saturn system and entered orbit around the planet. The main objectives of this mission, originally designed for 4 years, were to study the structure and dynamics of the rings and satellites, as well as to study the dynamics of the atmosphere and magnetosphere of Saturn and a detailed study of the planet's largest satellite, Titan.

Prior to entering orbit in June 2004, the AMS passed by Phoebe and sent high-resolution images of it and other data back to Earth. In addition, the American Cassini orbiter has repeatedly flown past Titan. Images were taken of large lakes and their coastlines with a significant number of mountains and islands. Then a special European probe "Huygens" separated from the device and parachuted down on January 14, 2005 to the surface of Titan. The descent took 2 hours and 28 minutes. During the descent, Huygens took samples of the atmosphere. According to the interpretation of data from the Huygens probe, the upper part of the clouds consists of methane ice, and the lower part of liquid methane and nitrogen.

Since the beginning of 2005, scientists have been observing the radiation coming from Saturn. On January 23, 2006, a storm occurred on Saturn, which produced a flash that was 1000 times more powerful than ordinary radiation. In 2006, NASA reported that the spacecraft had found obvious traces of water erupting from the geysers of Enceladus. In May 2011, NASA scientists stated that Enceladus "proved to be the most habitable place in the solar system after Earth."

Saturn and its moons: in the center of the picture - Enceladus, on the right, close-up, half of Rhea is visible, with Mimas peeking out from behind. Photo taken by the Cassini probe, July 2011

The photographs taken by Cassini led to other significant discoveries. They revealed previously undiscovered rings of the planet outside the main bright region of the rings and inside the G and E rings. These rings have been named R/2004 S1 and R/2004 S2. It is assumed that the material for these rings could be formed as a result of an impact on Janus or Epimetheus by a meteorite or comet. In July 2006, Cassini images revealed the presence of a hydrocarbon lake near Titan's north pole. This fact was finally confirmed by additional images in March 2007. In October 2006 on south pole Saturn, a hurricane with a diameter of 8000 km was discovered.

In October 2008, Cassini transmitted images of the planet's northern hemisphere. Since 2004, when Cassini flew up to her, there have been noticeable changes, and now she is painted in unusual colors. The reasons for this are not yet clear. It is assumed that the recent change in colors is associated with the change of seasons. From 2004 to November 2, 2009, 8 new satellites were discovered with the help of the device. Cassini's main mission ended in 2008, when the device made 74 orbits around the planet. Then the probe's tasks were extended until September 2010, and then until 2017 to study the full cycle of Saturn's seasons.

In 2009, a joint American-European project between NASA and ESA appeared to launch the AMS Titan Saturn System Mission to study Saturn and its moons Titan and Enceladus. During it, the station will fly to the Saturn system for 7-8 years, and then become a satellite of Titan for two years. It will also launch a probe balloon into the atmosphere of Titan and a lander (possibly floating).

satellites

The largest satellites - Mimas, Enceladus, Tethys, Dione, Rhea, Titan and Iapetus - were discovered by 1789, but to this day remain the main objects of research. The diameters of these satellites vary from 397 (Mimas) to 5150 km (Titan), the semi-major axis of the orbit from 186 thousand km (Mimas) to 3561 thousand km (Iapetus). The mass distribution corresponds to the diameter distribution. Titan has the largest orbital eccentricity, Dione and Tethys the smallest. All satellites with known parameters are above the synchronous orbit, which leads to their gradual removal.

Satellites of Saturn

The largest of the moons is Titan. It is also the second largest in the solar system as a whole, after Jupiter's moon Ganymede. Titan is about half water ice and half rock. This composition is similar to some of the other large satellites of the gas planets, but Titan is very different from them in the composition and structure of its atmosphere, which is predominantly nitrogen, there is also a small amount of methane and ethane that form clouds. Besides the Earth, Titan is also the only body in the solar system for which the existence of liquid on the surface has been proven. The possibility of the emergence of the simplest organisms is not excluded by scientists. The diameter of Titan is 50% larger than that of the Moon. It also exceeds the size of the planet Mercury, although it is inferior to it in mass.

Other major satellites also have characteristics. So, Iapetus has two hemispheres with different albedo (0.03-0.05 and 0.5, respectively). Therefore, when Giovanni Cassini discovered this satellite, he found that it is visible only when it is on a certain side of Saturn. The leading and rear hemispheres of Dione and Rhea also have their differences. Dione's leading hemisphere is heavily cratered and uniform in brightness. The rear hemisphere contains dark areas, as well as a web of thin light stripes, which are ice ridges and cliffs. Distinctive feature Mimas is a huge Herschel impact crater with a diameter of 130 km. Similarly, Tethys has a 400 km diameter Odysseus crater. Enceladus, according to the images of Voyager 2, has a surface with areas of different geological age, massive craters in the middle and high northern latitudes and minor craters closer to the equator.

As of February 2010, 62 moons of Saturn are known. 12 of them were discovered using spacecraft: Voyager 1 (1980), Voyager 2 (1981), Cassini (2004-2007). Most of the satellites, except for Hyperion and Phoebe, have a synchronous rotation of their own - they are always turned to Saturn on one side. There is no information about the rotation of the smallest moons. Tethys and Dione are accompanied by two satellites at the Lagrange points L4 and L5.

During 2006, a team of scientists led by David Jewitt of the University of Hawaii working on the Japanese Subaru Telescope in Hawaii announced the discovery of 9 moons of Saturn. All of them belong to the so-called irregular satellites, which differ in retrograde orbit. The period of their revolution around the planet is from 862 to 1300 days.

Rings

Comparison of Saturn and Earth

Today, all four gaseous giants are known to have rings, but Saturn's are the most prominent. The rings are at an angle of approximately 28° to the plane of the ecliptic. Therefore, from the Earth, depending on relative position planets, they look different: they can be seen in the form of rings, and "on edge". As Huygens suggested, the rings are not continuous solid body, but consist of billions of tiny particles in orbit around the planet. This was proved by spectrometric observations by A. A. Belopolsky at the Pulkovo Observatory and by two other scientists in 1895-1896.

There are three main rings and the fourth is thinner. Together they reflect more light than the disk of Saturn itself. The three main rings are usually denoted by the first letters of the Latin alphabet. Ring B is the central one, the widest and brightest, it is separated from the outer ring A by the Cassini gap, almost 4000 km wide, in which there are the thinnest, almost transparent rings. Inside ring A there is a thin gap called Encke's dividing strip. Ring C, which is even closer to the planet than B, is almost transparent.

The rings of Saturn are very thin. With a diameter of about 250,000 km, their thickness does not reach even a kilometer (although there are also peculiar mountains on the surface of the rings). Despite its impressive appearance, the amount of substance that makes up the rings is extremely small. If it were assembled into one monolith, its diameter would not exceed 100 km. Probe images show that the rings are actually made up of thousands of rings interspersed with slits; the picture resembles the tracks of gramophone records. The particles that make up the rings range in size from 1 centimeter to 10 meters. By composition, they are 93% ice with minor impurities, which may include copolymers formed under the action of solar radiation and silicates, and 7% carbon.

There is a consistency in the movement of particles in the rings and satellites of the planet. Some of these, the so-called "shepherd satellites", play a role in keeping the rings in place. Mimas, for example, is in 2:1 resonance with the Cassinian gap, and under the influence of its attraction, the substance is removed from it, and Pan is located inside the Encke dividing strip. In 2010, data was received from the Cassini probe that suggests that Saturn's rings are oscillating. The fluctuations are made up of constant perturbations introduced by Mimas and spontaneous perturbations arising from the interaction of particles flying in the ring. The origin of Saturn's rings is not yet entirely clear. According to one of the theories put forward in 1849 by Eduard Rosh, the rings were formed as a result of the disintegration of a liquid satellite under the action of tidal forces. According to another, the satellite broke up due to the impact of a comet or asteroid.