The question of how the Earth arose has occupied the minds of people for more than one millennium. The answer to it has always depended on the level of knowledge of people. Initially, there were naive legends about the creation of the world by some divine power. Then the Earth in the works of scientists acquired the shape of a ball, which was the center of the universe. Then, in the 16th century, the doctrine of N. appeared, which placed the Earth in a series of planets revolving around the Sun. This was the first step in a truly scientific solution to the question of the origin of the Earth. Currently, there are several hypotheses, each of which in its own way describes the periods of the formation of the Universe and the position of the Earth in.

Kant-Laplace hypothesis

This was the first serious attempt to create a picture of the origin of the solar system from a scientific point of view. It is associated with the names of the French mathematician Pierre Laplace and the German philosopher Immanuel Kant, who worked at the end of the 18th century. They believed that the progenitor of the solar system is a hot gas-dust nebula, slowly rotating around a dense core in the center. Under the influence of forces of mutual attraction, the nebula began to flatten and turn into a huge disk. Its density was not uniform, so the disc was stratified into separate gas rings. Subsequently, each ring began to thicken and turn into a single gas clot rotating around its axis. Subsequently, the clots cooled down and turned into planets, and the rings around them into satellites.

The main part of the nebula remained in the center, still has not cooled down and has become the Sun. Already in the 19th century, the insufficiency of this hypothesis was discovered, since it could not always explain new data in science, but its value is still great.

The Soviet geophysicist O.Yu. Schmidt had a slightly different idea of ​​the development of the solar system, working in the first half of the 20th century. According to his hypothesis, the Sun, traveling through the Galaxy, passed through a gas and dust cloud and dragged part of it along with it. Subsequently, the solid particles of the cloud were subjected to sticking together and turned into planets, initially cold. The heating of these planets occurred later as a result of compression, as well as the influx of solar energy. The heating of the Earth was accompanied by massive outpourings of lavas to the surface as a result of activity. Thanks to this outpouring, the first covers of the Earth were formed.

They stood out from the lavas. They formed the primary, which did not yet contain oxygen. More than half of the volume of the primary atmosphere was water vapor, and its temperature exceeded 100°C. With further gradual cooling of the atmosphere occurred, which led to rainfall and the formation of a primary ocean. This happened about 4.5-5 billion years ago. Later, the formation of land began, which is thickened, relatively light parts that rise above ocean level.

J. Buffon's hypothesis

Not everyone agreed with the evolutionary scenario of the origin of planets around the Sun. Back in the 18th century, the French naturalist Georges Buffon made an assumption supported and developed by the American physicists Chamberlain and Multon. The essence of these assumptions is as follows: once another star swept in the vicinity of the Sun. Its attraction caused a huge one on the Sun, stretching out in space for hundreds of millions of kilometers. Having broken away, this wave began to twist around the Sun and break up into clots, each of which formed its own planet.

Hypothesis of F. Hoyle (XX century)

The English astrophysicist Fred Hoyle proposed his own hypothesis. According to her, the Sun had a twin star that exploded. Most of the fragments were carried away into outer space, the smaller part remained in the orbit of the Sun and formed planets.

All hypotheses interpret the origin of the solar system and the family ties between the Earth and the Sun in different ways, but they are unanimous in that all the planets originated from a single clot of matter, and then the fate of each of them was decided in its own way. The Earth had to go through a journey of 5 billion years, to experience a series of fantastic transformations, before we saw it in its modern form. However, it should be noted that there is still no hypothesis that does not have serious flaws and answers all questions about the origin of the Earth and other planets of the solar system. But it can be considered established that the Sun and the planets were formed simultaneously (or almost simultaneously) from a single material environment, from a single gas-dust cloud.

abstract

The solar system and its origin

Introduction

solar planet terrestrial

The solar system consists of a central celestial body - the star of the Sun, 9 large planets revolving around it, their satellites, many small planets - asteroids, numerous comets and the interplanetary medium. The major planets are arranged in order of removal from the Sun as follows: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto. One of the important issues related to the study of our planetary system is the problem of its origin. The solution of this problem has natural-scientific, ideological and philosophical significance. For centuries and even millennia, scientists have tried to figure out the past, present and future of the universe, including the solar system.

Subjectstudy of this work: The solar system, its origin.

Objective:study of the structure and features of the solar system, characterization of its origin.

Work tasks:consider possible hypotheses of the origin of the solar system, characterize the objects of the solar system, consider the structure of the solar system.

Relevance of the work:it is now believed that the solar system is quite well studied and devoid of any serious secrets. However, branches of physics have not yet been created that make it possible to describe the processes that occur immediately after the Big Bang, nothing can be said about the reasons that gave rise to it, and there remains a complete ambiguity regarding the physical nature of dark matter. The solar system is our home, so it is necessary to be interested in its structure, its history and prospects.

1. Origin of the solar system

.1 Hypotheses of the origin of the solar system

The history of science knows many hypotheses about the origin of the solar system. These hypotheses appeared before many important laws of the solar system became known. The significance of the first hypotheses is that they tried to explain the origin of celestial bodies as the result of a natural process, and not an act of divine creation. In addition, some early hypotheses contained correct ideas about the origin of celestial bodies.

In our time, there are two main scientific theories of the origin of the universe. According to the steady state theory, matter, energy, space and time have always existed. But then the question arises: why now no one manages to create matter and energy?

The most popular theory of the origin of the universe, supported by most theorists, is the big bang theory.

The big bang theory was proposed in the 1920s by Friedman and Lemaitre. According to this theory, once our Universe was an infinitesimal clot, superdense and hot to very high temperatures. This unstable formation suddenly exploded, the space rapidly expanded, and the temperature of the flying high-energy particles began to decrease. After about the first million years, the hydrogen and helium atoms became stable. Under the influence of gravity, clouds of matter began to concentrate. As a result, galaxies, stars, and other celestial bodies were formed. Stars aged, supernovae exploded, after which heavier elements appeared. They formed later generation stars such as our Sun. As evidence that a big bang occurred at one time, they talk about the redshift of light from objects located at large distances and the microwave background radiation.

In fact, explaining how and where it all began is still a serious problem. Or there was nothing from which everything could begin - no vacuum, no dust, no time. Or there was something, in which case it requires an explanation.

The big problem with the big bang theory is how the supposedly high-energy primordial radiation, flying in different directions, could coalesce into structures such as stars, galaxies, and clusters of galaxies. This theory assumes the presence of additional sources of mass that provide the appropriate values ​​of the attractive force. The matter that was never found was called cold dark matter. For the formation of galaxies, it is necessary that such matter make up 95-99% of the Universe.

Kant developed a hypothesis according to which at first the world space was filled with matter, which was in a state of chaos. Under the influence of attraction and repulsion, matter eventually passed into more diverse forms. Elements with a higher density, according to the law of universal gravitation, attracted less dense ones, as a result of which separate clots of matter were formed. Under the action of repulsive forces, the rectilinear motion of particles towards the center of gravity was replaced by a circular motion. Due to the collision of particles around individual clusters, planetary systems were formed.

A completely different hypothesis about the origin of the planets was presented by Laplace. At an early stage of its development, the Sun was a huge, slowly rotating nebula. Under the influence of gravity, the protosun was compressed and took on an oblate shape. As soon as the force of gravity at the equator was balanced by the centrifugal force of inertia, a giant ring separated from the proto-sun, which cooled and broke into separate clots. From them the planets were formed. Such separation of the rings occurred several times. The satellites of the planets were formed in a similar way. Laplace's hypothesis proved unable to explain the redistribution of momentum between the Sun and the planets. For this and other hypotheses, according to which planets are formed from hot gas, the stumbling block is the following: a planet cannot form from hot gas, since this gas expands and dissipates very quickly in space.

An important role in the development of views on the origin of the planetary system was played by the work of our compatriot Schmidt. His theory is based on two assumptions: the planets formed from a cold gas and dust cloud; this cloud was captured by the Sun as it orbited the center of the Galaxy. Based on these assumptions, it was possible to explain some patterns in the structure of the solar system - the distribution of planets by distance from the Sun, rotation, etc.

There were many hypotheses, but if each of them well explained part of the research, then the other part did not explain. When developing a cosmogonic hypothesis, first of all, it is necessary to solve the question: where did the substance come from, from which the planets eventually formed? There are three options here:

1.Planets are formed from the same gas and dust cloud as the Sun (I. Kant).

2.The cloud from which the planets were formed was captured by the Sun during its revolution around the center of the Galaxy (O.Yu. Schmidt).

3.This cloud separated from the Sun in the course of its evolution (P. Laplace, D. Jeans, etc.)

1.2 Theory of the origin of the Earth

The process of formation of the planet Earth, like any of the planets, had its own characteristics. The earth was born about 5 109years ago at a distance of 1 AU. e. from the Sun. Approximately 4.6-3.9 billion years ago, it was intensely bombarded by interplanetary debris and meteorites; when they fell to Earth, their substance was heated and crushed. The primary substance was compressed under the influence of gravity, took the form of a ball, the depths of which were heated up. Mixing processes took place, chemical reactions took place, lighter silicate rocks were squeezed out from the depths to the surface and formed the earth's crust, while heavy ones remained inside. The heating was accompanied by violent volcanic activity, vapors and gases burst out. The terrestrial planets at first did not have atmospheres, as on Mercury and the Moon. The activation of processes on the Sun caused an increase in volcanic activity, the hydrosphere and atmosphere were born from magma, clouds appeared, water vapor condensed in the oceans.

The formation of oceans does not stop on Earth until now, although this is no longer an intensive process. The earth's crust is being renewed, volcanoes emit huge amounts of carbon dioxide and water vapor into the atmosphere. Earth's early atmosphere consisted mainly of CO 2. A sharp change in the composition of the atmosphere occurred about 2 billion years ago, it is associated with the creation of the hydrosphere and the origin of life. Carboniferous plants absorbed most of the CO 2and saturate the atmosphere with O 2. The composition of the Earth's atmosphere has remained practically unchanged for the last 200 million years. This is evidenced by deposits of coal and thick layers of carbonate deposits in sedimentary rocks. They contain a large amount of carbon, which was previously part of the atmosphere in the form of CO2. and SO.

The time of the existence of the Earth is divided into 2 periods: early history and geological history.

I. Early Earth History is divided into three phases: the birth phase, the melting phase of the outer sphere, and the phase of the primary crust (lunar phase).

Birth phase lasted 100 million years. During the birth phase, the Earth acquired approximately 95% of its current mass.

The melting phase dates back to 4.6-4.2 billion years ago. The Earth remained a cold cosmic body for a long time, only at the end of this phase, when an intense bombardment of it by large objects began, a strong heating occurred, and then a complete melting of the substance of the outer zone and the inner zone of the planet. The phase of gravitational differentiation of matter has come: heavy chemical elements descended, light ones rose upwards. Therefore, in the process of differentiation of matter, heavy chemical elements (iron, nickel, etc.) were concentrated in the center of the Earth, from which the core was formed, and the Earth's mantle arose from lighter compounds. Silicon became the basis for the formation of continents, and the lightest chemical compounds formed the oceans and the Earth's atmosphere. In the earth's atmosphere, initially there was a lot of hydrogen, helium, and such hydrogen-containing compounds as methane, ammonia, and water vapor.

The lunar phase lasted 400 million years from 4.2 to 3.8 billion years ago. At the same time, the cooling of the molten substance of the outer sphere of the Earth led to the formation of a thin primary crust. At the same time, the formation of the granite layer of the continental crust took place. The continents are composed of rocks containing 65-70% silica and significant amounts of potassium and sodium. The bed of the oceans is lined with basalts - rocks containing 45-50% Si0 2 and rich in magnesium and iron. Continents are built with less dense material than the ocean floor.

II. Geological history - this is the period of the development of the Earth as a planet as a whole, especially its crust and natural environment. After cooling the earth's surface to a temperature below 100 ° C, a huge mass of liquid water formed on it, which was not a simple accumulation of still waters, but those in an active global cycle. The Earth has the largest mass of the terrestrial planets and therefore has the largest internal energy - radiogenic, gravitational.

Due to the greenhouse effect, the surface temperature rises, instead of -23°C it became +15°C. If this did not happen, then in the natural environment liquid water would not be 95% of the total amount in the hydrosphere, but many times less.

The Sun provides the Earth with the heat it needs to keep its temperature within a suitable range. It should be borne in mind that a small change of only a few percent in the amount of heat received by the Earth from the Sun will lead to large changes in the Earth's climate. The earth's atmosphere plays an extremely important role in maintaining temperatures within acceptable limits. It acts like a blanket, preventing temperatures from getting too high during the day and too cold at night.

2. The composition of the solar system and its features

.1 The structure of the solar system

The main patterns observed in the structure, movement, properties of the solar system:

1. The orbits of all the planets (except the orbit of Pluto) lie almost in the same plane, almost coinciding with the plane of the solar equator.
2. All planets revolve around the Sun in almost circular orbits in the same direction, coinciding with the direction of the Sun's rotation around its axis.
3. The direction of the axial rotation of the planets (with the exception of Venus and Uranus) coincides with the direction of their revolution around the Sun.
4. The total mass of the planets is 750 times less than the mass of the Sun (almost 99.9% of the mass of the solar system falls on the sun), but they account for 98% of the total angular momentum of the entire solar system.
5. The planets are divided into two groups, which differ sharply in structure and physical properties - the terrestrial planets and the giant planets.

Planets make up the bulk of the solar system.

The planets that are closest to the Sun (Mercury, Venus, Earth, Mars) are very different from the next four. They are called terrestrial planets because, like the Earth, they are composed of solid rocks. Jupiter, Saturn, Uranus and Neptune are called giant planets and are made up mostly of hydrogen.

Ceres is the name of the largest asteroid, with a diameter of about 1000 km.

These are blocks with diameters that do not exceed several kilometers in size. Most asteroids revolve around the sun in a wide "asteroid belt" that lies between Mars and Jupiter. The orbits of some asteroids go far beyond this belt, and sometimes approach close to the Earth.

These asteroids cannot be seen with the naked eye because they are too small and very far away from us. But other debris - like comets - can be seen in the night sky due to their bright glow.

Comets are celestial bodies that are made up of ice, solid particles and dust. Most of the time, the comet moves in the far reaches of our solar system and is invisible to the human eye, but when it approaches the Sun, it begins to glow. This happens under the influence of solar heat.

Meteorites are large meteoroids that reach the earth's surface. Due to the collision of huge meteorites with the Earth, in the distant past, huge craters formed on its surface. Almost a million tons of meteorite dust falls on Earth every year.

2.2 Terrestrial planets

The general patterns of development of the terrestrial planets include the following:

.All planets originated from a single gas and dust cloud (nebula).

1. Approximately 4.5 billion years ago, under the influence of the rapid accumulation of thermal energy, the outer shell of the planets underwent complete melting.
2. As a result of the cooling of the outer layers of the lithosphere, a crust was formed. At an early stage in the existence of the planets, their matter was differentiated into a core, mantle, and crust.
3. The development of the outer region of the planets took place individually. The most important condition here is the presence or absence of an atmosphere and hydrosphere on the planet.

Mercury is the closest planet to the Sun in the solar system. The distance from Mercury to the Sun is only 58 million km. Mercury is a bright star, but it is not so easy to see it in the sky. Being close to the Sun, Mercury is always visible to us not far from the solar disk. Therefore, it can be seen only on those days when it departs from the Sun at its greatest distance. Mercury was found to have a highly rarefied gas envelope, consisting mainly of helium. This atmosphere is in dynamic equilibrium: each helium atom stays in it for about 200 days, after which it leaves the planet, and another particle from the solar wind plasma takes its place. Mercury is much closer to the Sun than Earth. Therefore, the Sun on it shines and warms 7 times stronger than ours. On the day side of Mercury, it is terribly hot, the temperature there rises to 400 O above zero. But on the night side there is always a strong frost, which probably reaches 200 O below zero. One half of it is a hot stone desert, and the other half is an icy desert covered with frozen gases.

Venus is the second closest planet to the Sun, almost the same size as the Earth, and its mass is more than 80% of the Earth's mass. For these reasons, Venus is called the twin or sister of the Earth. However, the surface and atmosphere of these two planets are completely different. The Earth has rivers, lakes, oceans and the atmosphere we breathe. Venus is a scalding hot planet with a dense atmosphere that would be fatal to humans. Venus receives more than two times more light and heat from the Sun than the Earth, from the shadow side, Venus is dominated by a frost of more than 20 degrees below zero, since the sun's rays do not fall here. The planet has a very dense, deep and cloudy atmosphere, making it impossible to see the surface of the planet. The planet has no satellites. The temperature is about 750 K over the entire surface both day and night. The reason for such a high temperature near the surface of Venus is the greenhouse effect: the sun's rays easily pass through the clouds of its atmosphere and heat the surface of the planet, but the thermal infrared radiation of the surface itself escapes through the atmosphere back into space with great difficulty. The atmosphere of Venus is composed primarily of carbon dioxide (CO 2) - 97%. Hydrochloric and hydrofluoric acids were found in the form of small impurities. During the day, the surface of the planet is illuminated by scattered sunlight with about the same intensity as on an overcast day on Earth. A lot of lightning has been seen on Venus at night. Venus is covered with solid rocks. Hot lava circulates beneath them, causing tension in a thin surface layer. Lava is constantly erupting from holes and fissures in solid rock.

On the surface of Venus, a rock rich in potassium, uranium and thorium was found, which, under terrestrial conditions, corresponds to the composition of secondary volcanic rocks. Thus, the surface rocks of Venus turned out to be the same as on the Moon, Mercury and Mars, erupted igneous rocks of the basic composition.

Little is known about the interior of Venus. It probably has a metal core taking up 50% of its radius. But the planet does not have a magnetic field due to its very slow rotation.

Earth is the third planet from the Sun in the solar system. The shape of the Earth is close to an ellipsoid, flattened at the poles and stretched in the equatorial zone. The surface area of ​​the Earth is 510.2 million km ², of which approximately 70.8% is in the oceans. Land makes up 29.2%, respectively, and forms six continents and islands. Mountains occupy more than 1/3 of the land surface.

Due to its unique conditions, the Earth became the place where organic life arose and developed. Approximately 3.5 billion years ago, conditions favorable for the emergence of life arose. Homo sapiens (Homo sapiens) as a species appeared about half a million years ago.

The period of revolution around the Sun is 365 days, with a daily rotation - 23 hours 56 minutes. The axis of rotation of the Earth is located at an angle of 66.5º .

Earth's atmosphere is 78% nitrogen and 21% oxygen. Our planet is surrounded by a vast atmosphere. According to temperature, the composition and physical properties of the atmosphere can be divided into different layers. The troposphere is the region between the Earth's surface and a height of 11 km. This is a rather thick and dense layer containing most of the water vapor in the air. Almost all atmospheric phenomena that are of direct interest to the inhabitants of the Earth take place in it. The troposphere contains clouds, precipitation, etc. The layer separating the troposphere from the next atmospheric layer, the stratosphere, is called the tropopause. This is an area of ​​very low temperatures.

The Moon is a natural satellite of the Earth and the closest celestial body to us. The average distance to the Moon is 384,000 kilometers, the diameter of the Moon is about 3476 km. Not being protected by the atmosphere, the surface of the Moon heats up to +110 C during the day, and cools down to -120 ° C at night. The origin of the Moon is the subject of a number of hypotheses. One of them is based on the theories of Jeans and Lyapunov - the Earth rotated very quickly and threw off part of its substance, the other - on the capture of a passing celestial body by the Earth. The most plausible hypothesis is the collision of the Earth with a planet whose mass corresponds to the mass of Mars, which occurred at a large angle, as a result of which a huge ring of debris was formed, which formed the basis for the Moon. It was formed near the Sun due to the earliest pre-metallic condensates at high temperatures.

Mars is the fourth planet in the solar system. In diameter, it is almost half the size of Earth and Venus. The average distance from the Sun is 1.52 AU. It has two satellites - Phobos and Deimos.

The planet is shrouded in a gaseous shell - an atmosphere that has a lower density than the earth's. In composition, it resembles the atmosphere of Venus and contains 95.3% carbon dioxide with an admixture of 2.7% nitrogen.

The average temperature on Mars is much lower than on Earth, about -40 ° C. Under the most favorable conditions in the summer in the daytime half of the planet, the air warms up to 20 ° C. But on winter nights, frost can reach -125 ° C. Such sharp temperature drops are caused by that the rarefied atmosphere of Mars is not able to retain heat for a long time. Strong winds blow over the surface of the planet, the speed of which reaches 100 m/s.

There is very little water vapor in the atmosphere of Mars, but at low pressure and temperature it is in a state close to saturation, and often collects in clouds. The Martian sky in clear weather has a pinkish color, which is explained by the scattering of sunlight on dust particles and the illumination of the haze by the orange surface of the planet.

The surface of Mars, at first glance, resembles the moon. However, in fact, its relief is very diverse. Throughout the long geological history of Mars, its surface has been altered by volcanic eruptions.

.3 Giant planets

The giant planets are the four planets of the solar system: Jupiter, Saturn, Uranus, Neptune. These planets, which share a number of similar physical characteristics, are also called outer planets.

Unlike the terrestrial planets, they are all gas planets, have significantly larger sizes and masses, lower density, powerful atmospheres, fast rotation, as well as rings (while the terrestrial planets do not have such) and a large number of satellites.

The giant planets rotate very quickly around their axes; Jupiter takes less than 10 hours to make one revolution. Moreover, the equatorial zones of the giant planets rotate faster than the polar ones.

The giant planets are far from the Sun, and regardless of the nature of the change of seasons, they are always dominated by low temperatures. On Jupiter, there is no change of seasons at all, since the axis of this planet is almost perpendicular to the plane of its orbit.

The giant planets are distinguished by a large number of satellites; Jupiter has 16 of them, Saturn - 17, Uranus - 16, and only Neptune - 8. A remarkable feature of the giant planets is the rings that are open not only for Saturn, but also for Jupiter, Uranus and Neptune.

The most important feature of the structure of the giant planets is that these planets do not have solid surfaces, since they consist mainly of hydrogen and helium. In the upper layers of the hydrogen-helium atmosphere of Jupiter, chemical compounds, hydrocarbons (ethane, acetylene), as well as various compounds containing phosphorus and sulfur, are found in the form of impurities, coloring the details of the atmosphere in red-brown and yellow colors. Thus, in their chemical composition, the giant planets differ sharply from the terrestrial planets.

Unlike the terrestrial planets, which have a crust, mantle and core, on Jupiter, gaseous hydrogen, which is part of the atmosphere, passes into a liquid, and then into a solid (metal) phase. The appearance of such unusual states of aggregation of hydrogen is associated with a sharp increase in pressure as one goes deeper.

The giant planets account for 99.5% of the total mass of the solar system (excluding the Sun). Of the four giant planets, Jupiter is the best studied and is the largest and closest of this group to the Sun. It is 11 times larger than 3 Earths in diameter and 300 times in mass. The period of its revolution around the Sun is almost 12 years.

Since the giant planets are far from the Sun, their temperature (at least above their clouds) is very low: on Jupiter - 145 ° C, on Saturn - 180 ° C, on Uranus and Neptune even lower.

The average density of Jupiter is 1.3 g/cm3, Uranus 1.5 g/cm3, Neptune 1.7 g/cm3, and Saturn even 0.7 g/cm3, that is, less than the density of water. The low density and abundance of hydrogen distinguish the giant planets from the rest.

The only formation of its kind in the solar system is a flat ring several kilometers thick surrounding Saturn. It is located in the plane of the planet's equator, which is inclined to the plane of its orbit by 27°. Therefore, during the 30-year revolution of Saturn around the Sun, the ring is visible to us either quite open, or exactly edge-on, when it can be seen in the form of a thin line only with large telescopes. The width of this ring is such that, if it were continuous, the globe could roll along it.

Conclusion

Thus, two theories of the origin of the Universe are distinguished: the theory of a stable state, according to which matter, energy, space and time have always existed, and the theory of the Big Bang, which says that the Universe, which seems to be an infinitely small hot bunch, suddenly exploded, resulting in clouds matter from which galaxies subsequently emerged.

Three points of view on the process of planet formation have become widespread: 1) the planets were formed from the same gas and dust cloud as the Sun (I. Kant); 2) the cloud from which the planets were formed was captured by the Sun during its revolution around the center of the Galaxy (O.Yu. Schmidt); 3) this cloud separated from the Sun during its evolution
(P. Laplace, D. Jeans and others). The time of the existence of the Earth is divided into 2 periods: early history and geological history. The early history of the Earth is represented by such stages of development as: the birth phase, the melting phase of the outer sphere and the phase of the primary crust (lunar phase). Geological history - this is the period of the development of the Earth as a planet as a whole, especially its crust and natural environment. The geological history of the Earth is characterized by the appearance of the atmosphere and the transition of water vapor into liquid water; the evolution of the biosphere is a process of development of the organic world, starting with the simplest cells of the Archean period, and ending with the emergence of mammals in the Cenozoic period.

The process of the birth of the Earth had its own characteristics. Approximately 4.6-3.9 billion years ago, it was intensely bombarded by interplanetary debris and meteorites. The primary substance was compressed under the influence of gravity, took the form of a ball, the depths of which were heated up.

Mixing processes took place, chemical reactions took place, lighter rocks were squeezed out from the depths to the surface and formed the earth's crust, while heavy ones remained inside. The heating was accompanied by violent volcanic activity, vapors and gases burst out.

The planets are in the following order from the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto.

The terrestrial planets have a solid shell, unlike the giant planets, which have a gaseous one. The giant planets are several times larger than the terrestrial planets. Giant planets have a low average density compared to other planets. The terrestrial planets have a mantle crust and a core, while on Jupiter, gaseous hydrogen, which is part of the atmosphere, first passes into a liquid, then into a solid metal phase. The appearance of such states of aggregation of hydrogen is associated with a sharp increase in pressure as one goes deeper. The giant planets also have powerful atmospheres and rings.

Bibliographic list

1.Gromov A.N. Amazing solar system. M.: Eksmo, 2012. -470 p. With. 12-15, 239-241, 252-254, 267-270.

2.Huseykhanov M.K. Concepts of modern natural science: Textbook. M .: "Dashkov and Co", 2007. - 540 p. With. 309, 310-312, 317-319, 315-316.

.Dubnishcheva T.Ya. Concepts of modern natural science: a textbook for university students. M.: "Academy", 2006. - 608 p. With. 379, 380

.Giant Planet Stats: #"justify">. The structure of the solar system: http://o-planete.ru/zemlya-i-vselennaya/stroenie-solnetchnoy-sistem.html

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Review of the main theories of the origin of the solar system.

1. Origin of the solar system;

2. Conclusions.

1. Origin of solar

systems.

For two centuries now, the problem of the origin of the solar system has been worrying the outstanding thinkers of our planet. This problem was dealt with, starting from the philosopher Kant and mathematics Laplace , a galaxy of astronomers and physicists of the XIX and XX centuries.

And yet we are still quite far from solving this problem. But over the past three decades, the question of the ways of the evolution of stars has become clearer. And although the details of the birth of a star from a gas-dust nebula are still far from clear, we now clearly understand what happens to it over billions of years of further evolution.

Turning to the presentation of various cosmogonic hypotheses that have replaced one another over the past two centuries, let's start with the hypothesis of the great German philosopher Kant and the theory that, several decades later, the French mathematician Laplace independently proposed. The prerequisites for the creation of these theories have stood the test of time.

TheoryKant.

For many centuries, the question of the origin of the Earth remained the monopoly of philosophers, since the actual material in this area was almost completely absent. The first scientific hypotheses regarding the origin of the Earth and the solar system, based on astronomical observations, were put forward only in the 18th century. Since then, more and more new theories have not ceased to appear, in accordance with the growth of our cosmogonic ideas.
The first in this series was the famous theory, formulated in 1755
German philosopher Immanuel Kant. Kant believed that the solar system arose from some primary matter, previously freely dispersed in space. Particles of this matter moved in different directions and, colliding with each other, lost speed. The heaviest and densest of them, under the influence of gravity, connected with each other, forming a central bunch - the Sun, which, in turn, attracted more distant, smaller and lighter particles.
Thus, a certain number of rotating bodies arose, the trajectories of which mutually intersected. Some of these bodies, initially moving in opposite directions, were eventually drawn into a single stream and formed rings of gaseous matter located approximately in the same plane and rotating around the Sun in the same direction without interfering with each other. In separate rings, denser nuclei were formed, to which lighter particles were gradually attracted, forming spherical accumulations of matter; this is how the planets were formed, which continued to circle around the Sun in the same plane as the original rings of gaseous matter

Nebular theoryLaplace.

In 1796, the French mathematician and astronomer Pierre-Simon Laplace put forward a theory somewhat different from the previous one. Laplace believed that the Sun originally existed in the form of a huge incandescent gaseous nebula (nebula) with an insignificant density, but colossal dimensions.
This nebula, according to Laplace, originally rotated slowly in space. Under the influence of gravitational forces, the nebula gradually contracted, and the speed of its rotation increased. The resulting increasing centrifugal force gave the nebula a flattened and then a lenticular shape. In the equatorial plane of the nebula, the ratio between attraction and centrifugal force changed in favor of the latter, so that eventually the mass of matter accumulated in the equatorial zone of the nebula separated from the rest of the body and formed a ring. From the nebula that continued to rotate, new rings were successively separated, which, condensing at certain points, gradually turned into planets and other bodies of the solar system. In total, ten rings separated from the original nebula, disintegrating into nine planets and a belt of asteroids - small celestial bodies. The satellites of individual planets were formed from the substance of the secondary rings, torn off from the hot gaseous mass of the planets.
Due to the continued compaction of matter, the temperature of the newly formed bodies was exceptionally high. At that time, our Earth, according to P. Laplace, was a hot gaseous ball that glowed like a star. Gradually, however, this ball cooled down, its matter passed into a liquid state, and then, as it cooled further, a solid crust began to form on its surface. This crust was enveloped in heavy atmospheric vapors, from which water condensed as it cooled. Since science did not have more acceptable explanations at that time, this theory had many followers in the 19th century.

The points of view of Kant and Laplace sharply differed on a number of important questions. Kant proceeded from the evolutionary development of a cold dusty nebula, during which the central massive body first arose - the future Sun, and then the planets, while Laplace considered the initial nebula to be gaseous and very hot with a high rotation speed. Compressing under the influence of the force of universal gravitation, the nebula, due to the law of conservation of angular momentum, rotated faster and faster. Due to the large centrifugal forces, rings were successively separated from it. Then they condensed to form planets.

Thus, according to Laplace's hypothesis, the planets formed before the sun. However, despite the differences, a common important feature is the idea that the solar system arose as a result of the regular development of the nebula. These two theories complemented each other, and therefore it is customary to call this concept the “Kant-Laplace hypothesis”.

However, this theory runs into a difficulty. Our solar system, consisting of nine planets of different sizes and masses, has a peculiarity: an unusual distribution of angular momentum between the central body - the Sun and the planets.

The angular momentum is one of the most important characteristics of any mechanical system isolated from the outside world. It is as such a system that the Sun and the planets surrounding it can be considered. Moment of momentum can be defined as the "reserve of rotation" of the system. This rotation is made up of the orbital motion of the planets and rotation around the axes of the Sun and planets.

The lion's share of the angular momentum of the solar system is concentrated in the orbital motion of the giant planets Jupiter and Saturn.

From the point of view of the Laplace hypothesis, this is completely incomprehensible. In the era when the ring separated from the original, rapidly rotating nebula, the layers of the nebula, from which the Sun later condensed, had (per unit mass) approximately the same moment as the substance of the separated ring (since the angular velocities of the ring and the remaining parts were approximately the same) , since the mass of the latter was much less than the main nebula (“protosun”), then the total angular momentum of the ring should be much less than that of the “protosun”. In Laplace's hypothesis, there is no mechanism for momentum transfer from the “protosun” to the ring. Therefore, during the entire further evolution, the angular momentum of the “proto-sun”, and then the Sun, must be much greater than that of the rings and the planets formed from them. But this conclusion contradicts the actual distribution of momentum between the Sun and the planets.

For Laplace's hypothesis, this difficulty turned out to be insurmountable.

Of the hypotheses of the origin of the solar system, the most famous is the electromagnetic hypothesis of the Swedish astrophysicist X . Alvena , improved F. Hoyle . Alven proceeded from the assumption that once the Sun had a very strong electromagnetic field. The nebula surrounding the star consisted of neutral atoms. Under the action of radiation and collisions, the atoms became ionized. The ions fell into "traps" from magnetic lines of force and were carried away after the rotating luminary. Gradually, the Sun lost its rotational moment, transferring it to a gas cloud.

The weakness of the proposed hypothesis was that the atoms of the lightest elements should have been ionized closer to the Sun, while the atoms of heavy elements - farther. This means that the planets closest to the Sun should have consisted of the lightest elements - hydrogen and helium, and the more distant ones - of iron and nickel. Observations say otherwise.

To overcome this contradiction, the English astronomer F. Hoyle proposed a new version of the hypothesis. The sun originated in the depths of the nebula. It rotated rapidly, and the nebula became more and more flat, turning into a disk. Gradually, the disk also began to accelerate, and the Sun slowed down. The moment of momentum passed to the disk. Then planets formed in it. If we assume that the original nebula already had a magnetic field, then a redistribution of angular momentum could well have occurred.

The solar system consists of nine planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto. All planets move in the same direction, in a single plane (with the exception of Pluto) in almost circular orbits. From the center to the outskirts of the solar system (to Pluto) 5.5 light hours. The distance from the Sun to the Earth is 149 million km (107 times the diameter of the Sun).

Small planets, like most satellites of planets, do not have an atmosphere, since the gravitational force on their surface is insufficient to hold gases. The atmosphere of Venus is dominated by carbon dioxide, while that of Jupiter is dominated by ammonia. There are volcanic craters on the Moon and Mars.

According to the hypothesis , put forward in 1945, the planets were formed from matter torn from the Sun as a result of a collision with a giant comet.

Among the subsequent cosmogonic theories, one can also find the theory of “catastrophes”, according to which our Earth owes its formation to some kind of outside interference, for example, a close meeting of the Sun with some wandering star that caused the eruption of part of the solar substance. As a result of the expansion, the hot gaseous matter quickly cooled and condensed, forming a large number of small solid particles, the clusters of which were something like the embryos of the planets.
In recent years, American and Soviet scientists have advanced a number of
new hypotheses. If earlier it was believed that in the evolution of the Earth there was a continuous process of heat transfer, then in new theories the development of the Earth is considered as the result of many heterogeneous, sometimes opposite processes. Simultaneously with the decrease in temperature and the loss of energy, other factors could also act, causing the release of large amounts of energy and thus compensating for the loss of heat. One of these modern assumptions, its author is an American astronomer (1948) called "the dust cloud theory". However, in essence, this is nothing more than a modified version of the nebular theory of Kant-Laplace.
It is curious that at a new level, armed with more advanced
technology and deeper knowledge of the chemical composition of the solar system, astronomers have returned to the idea that the Sun and planets arose from a vast, non-cold nebula, consisting of gas and dust. Powerful telescopes have detected numerous gas and dust "clouds" in interstellar space, some of which are actually condensing into new stars.
In this regard, the original Kant-Laplace theory was revised using the latest data; it can still serve well in explaining the process by which the solar system came into being.
Each of these cosmogonic theories has contributed to the clarification of a complex set of problems associated with the origin of the Earth. All of them consider the emergence of the Earth and the solar system as a natural result of the development of stars and the universe as a whole. The Earth appeared simultaneously with other planets, which, like it, revolve around the Sun and are the most important elements of the solar system.

Conclusions.

The variety of hypotheses is due to the fact that the planets of the solar system are quite different from each other: Mercury, Venus, Mars, Earth are solid planets; Jupiter, Saturn, Uranus, Neptune - gaseous; Pluto is an unformed solid planet.

Such a strange arrangement of the planets, as well as the existence of an asteroid belt between the orbits of Mars and Jupiter (probably these are the remains of another planet) explains the fact that there is still no generally accepted theory of the solar system that gives consistent answers to these and other questions.

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Introduction

The solar system formed about 4.6 billion years ago. It consists of celestial bodies - these are stars, including the Sun, 8 planets and their satellites, as well as asteroids and comets. The planets are arranged in order of distance from the Sun as follows: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto. All celestial bodies revolve around a massive star (the Sun) in elliptical (Fig. 15) orbits.

The central object of the solar system is the Sun, to which the vast majority of the entire mass of the system is concentrated, it holds the planets and other bodies belonging to the solar system with its gravity. Sometimes the solar system is divided into regions. The inner part of the solar system includes four terrestrial planets and an asteroid belt. The outer part begins outside the asteroid belt and includes four gas giants. Planets inside the asteroid region are sometimes called inner, and outside the belt - outer.

One of the important questions connected with the study of our planetary system is the problem of its origin. At present, when testing one or another hypothesis about the origin of the solar system, it is largely based on data on the chemical composition and age of the rocks of the Earth and other bodies of the solar system. The solution of this problem has natural-scientific, ideological and philosophical significance. Our goal is to establish the chronology of the development of ideas about the origin of the solar system.

Analysis of the development of hypotheses about the origin of the solar system

Time	Personality	History of personality	The essence of the hypothesis
384 BC e.	Aristotle (Fig. 1)	Ancient Greek philosopher, student of Plato.	He argued that the Earth is the center of the universe.
	Claudius Ptolemy (Fig. 2)	Ptolemy lived and worked in Alexandria, where he made astronomical observations. He was an astronomer, astrologer, mathematician, mechanic, optician, music theorist and geographer. There is no mention of his life and work in the sources.	Ptolemy was the first to propose a model of the universe. According to this model, the stationary Earth occupies the central position in the Universe, and the Sun, Moon, planets and stars revolve around it in different spheres. His model was accepted by Christian theologians and, in fact, canonized - elevated to the rank of absolute truths.
	Nicolaus Copernicus (Fig. 3)	Polish astronomer, mathematician, mechanic, economist, canon of the Renaissance. He is best known as the author of the heliocentric system of the world, which marked the beginning of the first scientific revolution. The heliocentric system of the world (heliocentrism) is the idea that the Sun is the central celestial body around which the Earth and other planets revolve.	Nicolaus Copernicus refuted the hypothesis of Claudius Ptolemy and scientifically proved that the Earth is not the center of the universe. Copernicus placed the Sun at the center and created a heliocentric model of the universe. Copernicus was afraid of the persecution of the church and therefore gave his work to print shortly before his death. But the church officially banned his book.
	Galileo Galilei (Fig. 4)	Italian physicist, mechanic, astronomer, philosopher, mathematician, who had a significant impact on the science of his time. He was the first to use a telescope to observe celestial bodies and made a number of outstanding astronomical discoveries.	Galileo Galilei was a supporter of the teachings of Copernicus. He first used a telescope to study the starry sky and saw that the universe is much larger than previously thought, and that there are satellites around the planets, which, like the planets around the Sun, revolve around their planets. Galileo experimentally studied the laws of motion. But the church staged a persecution of the scientist and inflicted on him the court of the Inquisition.
	Giordano Bruno (Fig. 5)	Italian Dominican friar, pantheist philosopher and poet, and also recognized as an outstanding thinker of the Renaissance.	Giordano Bruno created the doctrine that the stars are like the Sun, that the planets also move in orbits around the stars. He also argued that in the universe there are many inhabited worlds, that in addition to man in the universe there are other thinking beings. But for this, Giordano was condemned by the Christian Church and burned at the stake.
	Rene Descartes (Fig. 6)	French philosopher, mathematician, mechanic, physicist and physiologist, creator of analytic geometry and modern algebraic symbolism.	Descartes believed that the universe is entirely filled with moving matter. According to him, the solar system was formed from the primary nebula, which had the shape of a disk and consisted of gas and dust. This theory bears a marked resemblance to the theory currently accepted.
	Buffon Georges Louis Leclerc (Fig. 7)	French naturalist, biologist, mathematician, naturalist and writer. In 1970, a crater on the Moon was named after Buffon.	In 1745, Buffon suggested that the matter from which the planets are formed was torn away from the Sun by some large comet or star passing too close. But if Buffon were right, then the appearance of such a planet, for example, as ours, would be an extremely rare event, and the probability of finding life somewhere in the Universe would become negligible.
	Immanuel Kant (Fig. 8)	German philosopher and founder of German classical philosophy. Kant wrote fundamental philosophical works that brought the scientist a reputation as one of the outstanding thinkers of the 18th century and had a huge impact on the further development of world philosophical thought.	Well-known theories were the theories of the mathematician Laplace and the philosopher Kant, the essence of which is that stars and planets were formed from cosmic dust by gradual compression of the original gas and dust nebula. But the hypotheses of Kant and Laplace differed. Kant proceeded from the evolutionary development of a cold dusty nebula, during which the central body, the Sun, first arose, and then the planets. Here is Laplace's conjecture...
	Pierre-Simon Laplace (Fig. 9)	French mathematician, mechanic, physicist and astronomer. He is known for his work in the field of celestial mechanics, one of the creators of the theory of probability and the “Laplace Demon Paradox”. His name is included in the list of the greatest scientists of France, placed on the first floor of the Eiffel Tower.	According to Laplace, the planets formed before the Sun. That is, the original nebula was gaseous and hot and rotated rapidly. Due to centrifugal forces in the equatorial belt, rings were successively separated from it. Subsequently, these rings condensed, and the planets turned out. (Fig. 17)
	James Hopwood Jeans (Fig. 10)	British theoretical physicist, astronomer and mathematician. He made important contributions to several areas of physics, including quantum theory, the theory of thermal radiation, and the evolution of stars.	The hypothesis of Jeans is completely opposite to that of Kant and Laplace. She explains the formation of the solar system by chance, considering it a rare occurrence. The substance from which the planets later formed was ejected from a rather "old" Sun. Thanks to tidal forces acting from the side of an incoming star, which happened to pass near the Sun, a jet of gas was ejected from the surface layers of the Sun. This jet remained in the sphere of gravity of the Sun. Subsequently, the jet condensed, and the planets turned out. But if the Jeans hypothesis were correct, then there would be much fewer planetary systems in the Galaxy. Therefore, the Jeans hypothesis should be rejected. (Fig. 16,19)
			Wolfson suggested that the gas jet from which the planets were formed was ejected from a huge loose star flying past. Calculations show that if planetary systems were formed in this way, then there would be very few of them in the Galaxy. (Fig. 19)
	Hannes Olof Josta Alven (Fig. 12)	Swedish physicist, specialist in plasma physics, as well as Nobel Prize in Physics in 1970 for his work in the field of the theory of magnetohydrodynamics. In 1934 he taught physics at the University of Uppsala and in 1940 became professor of the theory of electromagnetism and electrical measurements at the Royal Institute of Technology in Stockholm.	Rescuing the hypothesis of Kant and Laplace, Alfven suggested that the Sun had a very strong electromagnetic field. The nebula surrounding the Sun consisted of neutral atoms. Under the influence of radiation and collisions - atoms were ionized. And the ions fell into traps from magnetic field lines and were carried away after the rotating Sun. Gradually, the Sun lost its rotational moment, transferring it to a gas cloud.
	Otto Yulievich Schmidt (Fig. 13)	Soviet mathematician, geographer, geophysicist, astronomer. One of the founders and chief editor of the Great Soviet Encyclopedia. From February 28, 1939 to March 24, 1942, he was vice-president of the USSR Academy of Sciences.	In 1944, Schmidt proposed a hypothesis according to which the planetary system was formed from matter captured from a gas-dust nebula through which the Sun once passed, which even then had an almost "modern" appearance. In this hypothesis, there are no difficulties with rotational moment. (Fig.18,20)
	Littleton Raymond Arthur (Fig. 14)		Beginning in 1961, the English cosmogonist Littleton developed Schmidt's hypothesis. It should be noted that in order for the Sun to capture a sufficient amount of matter, its velocity relative to the nebula must be very small, of the order of one hundred meters per second. Simply put, the Sun must be stuck in this cloud and move with it. In this hypothesis, the formation of planets is not associated with the process of star formation.

Conclusion

Here we come to the conclusion of the project. The process of formation of the solar system cannot be considered thoroughly studied. The origin of the solar system, the formation of galaxies and the origin of the universe is still far from complete. But the fact is that scientists observe a huge number of stars that are at different stages of evolution. The solar system and its origins are studied in many institutions around the world. This topic is given an important place in life.

From the project, two theories of the origin of the Solar System and the Universe itself as a whole can be distinguished. The first is about the Big Bang theory, and the second is that matter, energy, space and time have always existed.

We all have the right to believe that there are other planets on which life can exist, including intelligent life. At the beginning of the project, we said that our goal was to establish the chronology of the development of ideas about the origin of the solar system. And now we can say with confidence that our goal has been achieved.

Bibliography

Agekyan T.A. Stars, Galaxies, Metagalaxy. - M.: Nauka, 1970.

Weinberg S. The first three minutes. A modern view of the origin of the Universe (translated from English by Ya. Zel'dovich). - M.: Energoizdat, 1981.

Gorelov A.A. Concepts of modern natural science. - M.: Center, 1997.

Kaplan S.A. Physics of stars. - M.: "Science", 1970.

Xanfomality L.V. Planets rediscovered. - M.: Nauka, 1978.

Novikov I.D. Evolution of the Universe. - M.: Nauka, 1983.

Osipov Yu.S. Gravitational capture // Quark. - 1985. - No. 5.

Regge T. Etudes about the Universe. - M.: Mir, 1985.

Filippov E.M. Universe, Earth, life. - Kyiv: "Science thought", 1983.

Shklovsky I.S. Universe, life, mind. - M.: Nauka, 1980

http://mirznanii.com/a/183/proiskozhdenie-solnechnoy-system 1

http://ukhtoma.ru/universe8.htm 2

https://en.wikipedia.org 3

4. 5. 6. 7. 8. 9.

1 A star passes near the Sun, pulling matter out of it (Fig. A and B); planets are formed

of this material (fig. C)

Plan:

Introduction . 3

1. Hypotheses about the origin of the solar system .. 3

2. Modern theory of the origin of the solar system .. 5

3. The sun is the central body of our planetary system .. 7

4. Terrestrial planets .. 8

5. Giant planets .. 9

Conclusion . 11

List of used literature .. 12

Introduction

The solar system consists of a central celestial body - the star of the Sun, 9 large planets revolving around it, their satellites, many small planets - asteroids, numerous comets and the interplanetary medium. The major planets are arranged in order of removal from the Sun as follows: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto. The last three planets can only be observed from Earth through telescopes. The rest are visible as more or less bright circles and have been known to people since ancient times.

One of the important issues related to the study of our planetary system is the problem of its origin. The solution of this problem has natural-scientific, ideological and philosophical significance. For centuries and even millennia, scientists have tried to figure out the past, present and future of the universe, including the solar system. However, the possibilities of planetary cosmology to this day remain very limited - so far only meteorites and samples of lunar rocks are available for experiment in the laboratory. The possibilities of the comparative method of research are also limited: the structure and laws of other planetary systems have not yet been sufficiently studied.

1. Hypotheses about the origin of the solar system

To date, many hypotheses about the origin of the solar system are known, including those proposed independently by the German philosopher I. Kant (1724-1804) and the French mathematician and physicist P. Laplace (1749-1827). The point of view of I. Kant was the evolutionary development of a cold dusty nebula, during which the central massive body, the Sun, first arose, and then the planets were born. P. Laplace considered the original nebula to be gaseous and very hot, in a state of rapid rotation. Compressing under the influence of the force of universal gravitation, the nebula rotated faster and faster due to the law of conservation of angular momentum. Under the action of large centrifugal forces arising from the rapid rotation in the equatorial belt, rings were successively separated from it, turning into planets as a result of cooling and condensation. Thus, according to the theory of P. Laplace, the planets formed before the Sun. Despite such a difference between the two hypotheses under consideration, they both come from the same idea - the solar system arose as a result of the natural development of the nebula. And so this idea is sometimes called the Kant-Laplace hypothesis. However, this idea had to be abandoned due to many mathematical contradictions, and was replaced by several "tidal theories".

The most famous theory was put forward by Sir James Jeans, a famous popularizer of astronomy in the years between the First and Second World Wars. (He was also a leading astrophysicist, and it was only towards the end of his career that he turned to writing books for beginners.)

Rice. 1. Tidal theory of Jeans. A star passes by the sun

drawing substance out of it (Fig. A and B); planets are formed

of this material (fig. C)

According to Jeans, the planetary matter was "pulled out" from the Sun by a nearby star, and then disintegrated into separate parts, forming planets. At the same time, the largest planets (Saturn and Jupiter) are located in the center of the planetary system, where there was once a thickened part of the cigar-shaped nebula.

If this were indeed the case, then planetary systems would be extremely rare, since the stars are separated from each other by enormous distances, and it is quite possible that our planetary system could claim to be the only one in the Galaxy. But mathematicians attacked again, and eventually tidal theory joined gaseous Laplace rings in the wastebasket of science.

2. Modern theory of the origin of the solar system

According to modern concepts, the planets of the solar system formed from a cold gas and dust cloud that surrounded the Sun billions of years ago. This point of view is most consistently reflected in the hypothesis of the Russian scientist, Academician O.Yu. Schmidt (1891-1956), who showed that the problems of cosmology can be solved by the concerted efforts of astronomy and the Earth sciences, primarily geography, geology, and geochemistry. At the heart of the hypothesis O.Yu. Schmidt is the idea of ​​the formation of planets by combining solids and dust particles. The gas and dust cloud that emerged near the Sun initially consisted of 98% hydrogen and helium. The remaining elements condensed into dust particles. The chaotic movement of gas in the cloud quickly ceased: it was replaced by the calm movement of the cloud around the Sun.

Dust particles are concentrated in the central plane, forming a layer of increased density. When the density of the layer reached a certain critical value, its own gravitation began to "compete" with the gravitation of the Sun. The dust layer turned out to be unstable and disintegrated into separate dust clots. Colliding with each other, they formed many continuous dense bodies. The largest of them acquired almost circular orbits and in their growth began to overtake other bodies, becoming potential embryos of future planets. Like more massive bodies, neoplasms attached to themselves the remaining matter of the gas and dust cloud. In the end, nine large planets formed, the movement of which in orbits remains stable for billions of years.

Taking into account physical characteristics, all planets are divided into two groups. One of them consists of relatively small terrestrial planets - Mercury, Venus, Earth and Mars. Their substance is distinguished by a relatively high density: on average, about 5.5 g / cm 3, which is 5.5 times higher than the density of water. The other group is made up of the giant planets: Jupiter, Saturn, Uranus and Neptune. These planets have huge masses. Thus, the mass of Uranus is equal to 15 Earth masses, and Jupiter is 318. The giant planets consist mainly of hydrogen and helium, and the average density of their matter is close to the density of water. Apparently, these planets do not have a solid surface similar to the surface of the terrestrial planets. A special place is occupied by the ninth planet - Pluto, discovered in March 1930. It is closer in size to the terrestrial planets. Not so long ago it was discovered that Pluto is a double planet: it consists of a central body and a very large satellite. Both celestial bodies revolve around a common center of mass.

In the process of planet formation, their division into two groups is due to the fact that in parts of the cloud far from the Sun, the temperature was low and all substances, except hydrogen and helium, formed solid particles. Among them, methane, ammonia and water prevailed, which determined the composition of Uranus and Neptune. The composition of the most massive planets - Jupiter and Saturn, in addition, turned out to be a significant amount of gases. In the region of the terrestrial planets, the temperature was much higher, and all volatile substances (including methane and ammonia) remained in a gaseous state, and, therefore, were not included in the composition of the planets. The planets of this group were formed mainly from silicates and metals.

3. The sun is the central body of our planetary system

The Sun is the closest star to the Earth, which is a hot plasma ball. This is a gigantic source of energy: its radiation power is very high - about 3.86 × 10 23 kW. Every second, the Sun radiates such an amount of heat that would be enough to melt the layer of ice that surrounds the globe, a thousand kilometers thick. The sun plays an exceptional role in the origin and development of life on Earth. An insignificant part of solar energy falls on the Earth, thanks to which the gaseous state of the earth's atmosphere is maintained, the surfaces of land and water bodies are constantly heated, and the vital activity of animals and plants is ensured. Part of the solar energy is stored in the bowels of the Earth in the form of coal, oil, natural gas.

At present, it is generally accepted that thermonuclear reactions occur in the interior of the Sun at enormous temperatures - about 15 million degrees - and monstrous pressures, which are accompanied by the release of a huge amount of energy. One of these reactions may be the synthesis of hydrogen nuclei, in which the nuclei of the helium atom are formed. It is calculated that every second in the bowels of the Sun, 564 million tons of hydrogen are converted into 560 million tons of helium, and the remaining 4 million tons of hydrogen are converted into radiation. The thermonuclear reaction will continue until the supply of hydrogen runs out. They currently make up about 60% of the Sun's mass. Such a reserve should be sufficient for at least several billion years.

Almost all the energy of the Sun is generated in its central region, from where it is transferred by radiation, and then in the outer layer - it is transferred by convection. The effective temperature of the surface of the Sun - the photosphere - is about 6000 K.

Our Sun is not only a source of light and heat: its surface emits streams of invisible ultraviolet and X-rays, as well as elementary particles. Although the amount of heat and light sent to the Earth by the Sun remains constant for many hundreds of billions of years, the intensity of its invisible radiations varies significantly: it depends on the level of solar activity.

There are cycles during which solar activity reaches its maximum value. Their periodicity is 11 years. During the years of greatest activity, the number of spots and flares on the solar surface increases, magnetic storms occur on Earth, ionization of the upper atmosphere increases, etc.