Plan:

Introduction . 3

1. Hypotheses about the origin 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 orbiting around it, their satellites, many small planets - asteroids, numerous comets and the interplanetary medium. The major planets are arranged in order of distance from the Sun in the following way: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto. Three last 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 to this problem has a natural scientific, worldview and philosophical meaning. 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 - only meteorites and samples of lunar rocks are currently available for laboratory experiments. The possibilities of the comparative research method are also limited: the structure and patterns of other planetary systems have not yet been sufficiently studied.

1. Hypotheses about the origin of the solar system

By now, 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). Immanuel Kant's point of view was the evolutionary development of a cold dust nebula, during which first a central massive body - the Sun - 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 universal gravity, the nebula, due to the law of conservation of angular momentum, rotated faster and faster. Under the influence of large centrifugal forces arising during 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 this difference between the two hypotheses under consideration, they both proceed from the same idea - the Solar system arose as a result of the natural development of the nebula. And therefore this idea is sometimes called the Kant-Laplace hypothesis. However, this idea had to be abandoned due to many mathematical contradictions, and it 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 late in his career that he turned to writing books for beginners.)

Rice. 1. Jeans' tidal theory. A star passes near the Sun,

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

from this material (Fig. C)

According to Jeans, planetary matter was “ripped” out of the Sun under the influence of a nearby star, and then broke up into separate parts, forming planets. Moreover, the largest planets (Saturn and Jupiter) are located in the center of the planetary system, where the thickened part of the cigar-shaped nebula was once located.

If things really were this way, then planetary systems would be an extremely rare occurrence, since 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 the tidal theory joined the gaseous rings of Laplace in the dustbin of science.

2. Modern theory of the origin of the solar system

According to modern concepts, the planets of the solar system were formed from a cold cloud of gas and dust 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 Earth sciences, primarily geography, geology, and geochemistry. The hypothesis is based on O.Yu. Schmidt is the idea of ​​the formation of planets by combining solid bodies and dust particles. The gas and dust cloud that arose near the Sun initially consisted of 98% hydrogen and helium. The remaining elements condensed into dust particles. The random movement of gas in the cloud quickly stopped: it was replaced by a calm movement of the cloud around the Sun.

Dust particles concentrated in the central plane, forming a layer of increased density. When the layer density has reached a certain critical value, its own gravity began to “compete” with the gravity of the Sun. The dust layer turned out to be unstable and broke up into separate dust clumps. Colliding with each other, they formed many solid dense bodies. The largest of them acquired almost circular orbits and began to overtake other bodies in their growth, becoming potential embryos of future planets. As more massive bodies, the new formations absorbed the remaining matter of the gas and dust cloud. Eventually, nine large planets formed, whose orbits remained stable for billions of years.

Taking into account their 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 has a relatively high density: on average about 5.5 g/cm 3, which is 5.5 times the density of water. The other group consists of the giant planets: Jupiter, Saturn, Uranus and Neptune. These planets have enormous masses. Thus, the mass of Uranus is equal to 15 earth masses, and Jupiter is 318. Giant planets consist mainly of hydrogen and helium, and average density their substance is close to the density of water. Apparently, these planets do not have a solid surface, similar surface terrestrial planets. Special place The ninth planet is Pluto, discovered in March 1930. In size, it is closer to the terrestrial planets. It was recently discovered that Pluto is a double planet: it consists of a central body and a very large satellite. Both celestial bodies revolve around general center wt.

During the formation of planets, 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 predominated, which determined the composition of Uranus and Neptune. The most massive planets, Jupiter and Saturn, also contain 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 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 emits such an amount of heat that would be enough to melt the layer of ice surrounding the globe, a thousand kilometers thick. The sun plays an exceptional role in the emergence and development of life on Earth. An insignificant part of solar energy reaches 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 coal, oil, natural gas.

It is currently generally accepted that in the depths of the Sun, at extremely high temperatures - about 15 million degrees - and monstrous pressures, thermonuclear reactions occur, which are accompanied by the release of huge amounts of energy. One such reaction may be the fusion of hydrogen nuclei, which produces the nuclei of a helium atom. It is estimated that every second in the depths 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. Thermonuclear reaction will continue until the hydrogen supply runs out. They currently make up about 60% of the Sun's mass. Such a reserve should be enough 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 solar surface - the photosphere - is about 6000 K.

Our Sun is a source of not only 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 Earth by the Sun remains constant over many hundreds of billions of years, the intensity of its invisible radiation varies significantly: it depends on the level of solar activity.

Cycles are observed during which solar activity reaches its maximum value. Their frequency is 11 years. During the years of greatest activity, the number of sunspots and flares increases. solar surface, arise on Earth magnetic storms, ionization increases upper layers atmosphere, etc.

ORIGIN OF THE SOLAR SYSTEM

(planetary cosmogony). The origin and evolution of the Sun are considered by theories star formation And evolution of stars, and when studying P.S. basic attention is paid to the problem of the formation of planets, and primarily the Earth. Stars with planetary systems may form an intermediate class between single and double stars. It is possible that the structure of planetary systems and the methods of their formation can be very different. Structure solar system(SS) has a number of patterns indicating joint the formation of all planets and the Sun in a single process. Such patterns are: all planets in one elliptical direction. orbits lying almost in the same plane; rotation of the Sun in the same direction around an axis close to perpendicular to the center. planes of the planetary system; axial rotation in the same direction of most planets (with the exception of Venus, which rotates very slowly in reverse direction, and Uranus, which rotates as if lying on its side); the rotation of most of the planets' satellites in the same direction; a natural increase in the distances of planets from the Sun; division of planets into affinities. groups differing in mass, chemical. composition and number of satellites (terrestrial planets close to the Sun and giant planets far from the Sun, also divided into 2 groups); the presence of a belt of minor planets between the orbits of Mars and Jupiter.

Short story. The development of planetary cosmogony began with the Kant-Laplace hypothesis. I. Kant (I. Kant, 1755) put forward the idea of ​​the formation of planets from rarefied dusty matter orbiting the Sun. According to P. S. Laplace (1796), the material for the formation of planets was part of the gaseous substance separated from the contracting protosun. Along with the Kant-Laplace hypothesis, hypotheses based on the idea of ​​a “catastrophic event” were proposed. In the 1920-30s. The hypothesis of J. H. Jeans, who believed that the planets were formed from matter torn out of the Sun by the gravity of a passing star, was famous. However, already at the end. 30s It turned out that the Jeans hypothesis is not able to explain the size of the planetary system. A number of important studies on the problem of the formation of the circumsolar planet and the formation of planets in it were carried out in the 30-40s. H. Alfven and F. Hoyle drew attention to magnetohydrodynamics. effects playing important role in the early stages of the formation of a star and its environment. H. Berlage (N. Berlage) and K. Weizsäcker (S. Weizsacker) built the first gas-dynamic. models of the primary circumsolar disk. The beginning of the systematic development of the theory of PS. laid down by the works of O. Yu. Schmidt. In the works of the fatherland. Schools of planetary cosmogony have been clarified. features of the evolution of the protoplanetary disk and the processes accompanying the formation of planets. By the 80s. Extensive material of observational data on modern star formation was obtained. Thanks to space flights. devices, the amount of information about the structure, composition and properties of SS bodies has increased immeasurably. Lab. study of extraterrestrial matter and use of astrophysics in modeling. events made it possible to proceed to the construction of sufficiently detailed models of P.S.

Formation of the Sun and preplanetary disk. Stars solar type are formed in gas-dust complexes with mass M(M- mass of the Sun). An example of such a complex is the well-known nebula Orion, in which there is an active one. Apparently, the Sun was formed together with a group of stars during the intermittent processes of compression and fragmentation of such a nebula.

Evolution of the preplanetary disk: A- lowering the dust to the central plane; b- formation of a dust subdisk; V- disintegration of the dust subdisk into dust condensations; G- formation of compact bodies from dust condensations (according to B. Yu. Levin, 1964).

Evolution of the preplanetary disk: dynamic aspects. When modeling dep. stages of disk evolution (Fig.) and planet formation, much attention is paid to the beginning. stage - the lowering of dust particles to the center. disk planes and their adhesion in turbulent gas. The time of dust descent and the formation of a dust subdisk depends on the intensity of turbulent movements in the gas component of the disk and is estimated at - years. When the dust layer reaches critical. density as a result gravitational instability the dust subdisk would have to break up into dust condensations. At different distances from the Sun, the times of formation of dust concentrations and their masses could differ somewhat, but, according to estimates, on Wed. their masses were close to the masses of the largest modern ones. asteroids. Collisions of condensations caused the unification (and) of most of them and the formation of compact bodies - floatesimals. This process, with cosmogony. point of view, was also quite fast (years).

The next stage - the accumulation of planets from a swarm of planetesimals and their debris - took much longer (years). Numerical methods make it possible to simultaneously determine the masses and velocities of preplanetary bodies. At first, the bodies moved in circular orbits in the plane of the dust layer that gave birth to them. They grew, merging with each other and scooping up the surrounding scattered material (remnants of “primary” dust and debris formed during collisions of planetesimals). Gravity bodies, which intensified as they grew, gradually changed their orbits, increasing the avg. eccentricity and cf. tilt towards center disk plane. Naib. massive bodies turned out to be embryos of future planets. When many bodies were combined into planets, their individual characteristics of motion were averaged, and therefore the orbits of the planets turned out to be almost circular and coplanar. Estimated analytically and obtained in numerical calculations relates. distances between planets, their masses and total number, periods of their own. rotations, axial inclinations, eccentricities and orbital inclinations are in satisfactory agreement with observations.

The process of formation of giant planets was more complex, many of its details remain to be elucidated. Their formation was complicated by the long-term presence of gas and eff. release of substance into the external zones and even beyond the SS. According to models, the formation of Jupiter and Saturn occurred in two stages. At the first stage, which lasted tens of millions of years in the region of Jupiter and about one hundred million years in the region of Saturn, accumulation took place solids, similar to that which was in the zone of the terrestrial planets. When the largest bodies reached a certain swarm of critical. mass (5 Mz, Mz- the mass of the Earth), the 2nd stage of evolution began - gas on these bodies, which lasted for years. It dissipated from the zone of the terrestrial planets over the course of years; in the zone of Jupiter and Saturn it remained for several years. longer. The formation of the solid nuclei of Uranus and Neptune, located at great distances, took hundreds of millions of years. By this time, the gas from their surroundings had already been practically lost. Temperatures in this external parts of the SS did not exceed 100 K; as a result, in addition to the silicate component, the composition of these planets and their satellites included many condensates of water, methane and ammonia.

Small SS bodies - asteroids and comets- represent the remains of a swarm of intermediate bodies. The largest of modern asteroids (100 km across) were formed back in the era of the formation of the planetary system, and medium and small ones are mostly fragments of large asteroids that were crushed during collisions. Thanks to collisions of asteroid bodies, the supply of dust matter in interplanetary space is continuously replenished. Dr. a source of small solid particles - and the disintegration of cometary nuclei as they fly near the Sun. The nuclei of comets appear to be the remains of rocky-ice bodies in the zone of the giant planets. The masses of the giant planets, even before their growth was completed, became so large that their attraction began to greatly change the orbits of small bodies flying past them. As a result, some of these bodies acquired very elongated orbits, extending far beyond the boundaries of the planetary system. On bodies that moved further than 20-30 thousand a. e. from the Sun, noticeable gravity. the influence was exerted by nearby stars. In most cases, the influence of stars led to the fact that small bodies stopped entering the region of planetary orbits. The planetary system turned out to be surrounded by a swarm of rocky and icy bodies, extending to distances of a. e. and is the source of the currently observed comets (Oort cloud).

The origin of a system of regular satellites of planets, moving in the direction of rotation of the planet in almost circular orbits lying in the plane of its equator, is usually explained by processes similar to those that led to the formation of planets. According to models, during the formation of the planet as a result of inelastic collisions of planetesimals, some of them could be captured into a circumplanetary orbit, forming a circumplanetary pre-satellite disk. Estimates show that characteristic times the accumulation and destruction of small satellites during fragmentation is much less than the characteristic time of formation of the planet itself. The matter in the pre-satellite disks was repeatedly renewed before a relatively stable satellite system could be formed. According to model calculations, the masses of pre-satellite disks are equal to the mass of the planet, which is sufficient for the formation satellite systems giant planets. The system of regular satellites of Jupiter is divided into two groups: silicate and water-silicate. Differences in chem. composition of the moons show that young Jupiter was hot. Heating could be provided by the release of gravity. energy during gas accretion. In the system of satellites of Saturn, consisting mainly from ice, there is no division into two groups, which is associated with a lower temperature in the vicinity of Saturn, at which water could condense. The origin of the irregular satellites of Jupiter, Saturn and Neptune, i.e. satellites with reverse motion, as well as small external ones. Neptune's satellite, which has direct motion in an elongated orbit, is explained by capture. The slowly rotating planets (Mercury and Venus) have no satellites. They apparently experienced tidal braking from the planet and eventually fell onto it. The effect of tidal braking also manifested itself in the Earth - Moon and Pluto - Charon systems, where the satellites, forming a double system with the planet, are always turned towards the planet by the same hemisphere.

The origin of the Moon is most often associated with its formation in near-Earth orbit, but unlikely hypotheses of the Earth’s capture of the finished Moon and the separation of the Moon from the Earth continue to be discussed. A compromise hypothesis is also being developed, linking the appearance of a massive near-Earth pre-satellite disk with a gigantic ejection of matter caused by the collision of the proto-Earth with a large body (with dimensions on the order of Mercury or even Mars). According to calculations, a system of several could be formed from a massive satellite swarm. large satellites, the orbits of which evolved at different speeds under the influence of tidal friction, and, ultimately, the satellites merged into one body - the Moon.

Cosmochemical aspects (evolution of composition). Based on physical-chemical research early stages The evolution of the SS contains data on the composition of interstellar and interplanetary dust, planets and their atmospheres, asteroids and comets. A special place belongs to the laboratory. studies of meteorites - samples of asteroidal matter. The substance that entered the bodies of the SS underwent repeated physical-chemical tests. processing and has largely lost the memory of the early stages of evolution. However, dep. SS bodies contain a substance that stores this or that information in the form of relict mineral fractions, inclusions, etc. Samples of such substance are used as “cosmochronometers”, “cosmothermometers”, “cosmobarometers”.

Chem. The composition of the primary preplanetary disk is usually assumed to be close to the solar (“mean cosmic”). In the primary disk, gas (mainly hydrogen and helium) accounted for 98-99% of the total mass. Dust (ferromagnesian silicates and aluminosilicates in the inner part of the disk, to which ice was added in the outer part) initially played a secondary role. During the formation and evolution of the preplanetary disk, changes occurred in the elemental and isotopic composition of the gaseous and condensed components, and various exchanges between these two basic elements occurred. tanks. According to models, during the formation of a disk in the vicinity closest to the Sun interstellar dust During accretion it evaporated and only after partial cooling of the gas did recondensation of refractory and moderately refractory compounds occur. In ext. In the SS zone, the composition of the primary bodies could include an interstellar dust component. Lab. analyzes of samples max. primitive carbonaceous chondrites indicate the presence in them of a substance similar in elemental, isotopic and mineral composition To interstellar dust. In general, determinations of the isotopic composition of terrestrial and lunar samples, meteorites and interplanetary dust show relative homogeneity, and therefore good mixing of the base. mass of protoplanetary matter. This is a strong argument in favor of the formation of the preplanetary disk and the Sun in a single process. Thus, established for the Earth, Moon and oldest meteorites an age of 4.5-4.6 billion years can be considered the age of the SS. At the same time, the isotopic composition of the gaseous and condensed components undoubtedly changed during the formation of the disk and subsequently during the formation of planets. Interpretation of variations in the content of dep. isotopes in samples of extraterrestrial matter is often ambiguous and depends on the choice of dynamic. models. It is important, however, that the findings of daughter products of the decay of short-lived isotopes, etc., make it possible to obtain estimates of the duration of individual early stages. The obtained estimates, based on a number of isotopic systems, including extinct short-lived ones, do not contradict the dynamic. estimates of the duration of the stages of planet formation (years).

The interior of the largest primary bodies was heated to 300-700 K, and sometimes to 1000-1500 K, which is sufficient for partial and complete melting. This is evidenced by representatives of special classes of meteorites, composition and physical properties. the properties of which indicate that their parent bodies have gone through the stages of heating and differentiation of matter. The reasons for the heating are not entirely clear. Perhaps it was associated with the release of heat during the decay of short-lived radioacts. isotopes; creatures heating could be provided by mutual collisions.

Restrictions on the nature of the processes in the early SS were obtained by studying samples of extraterrestrial matter that interacted with galactic stars. and sunny cosmic rays. Thus, the study of grains of meteorite matter irradiated by solar cosmic particles. rays, allowed us to conclude that by the time of the formation of protoplanets in the terrestrial group zone, gas was mainly was already lost. This is an important argument in favor of the idea that the atmospheres of the Earth, Venus and Mars are secondary.

Initial state and evolution of planets. As a result of collisions of growing planets with bodies 100-1000 km in size, protoplanets were experienced. heating, degassing, and differentiation of the subsoil. Isotope analysis (based on uranium and lead isotopes) indicates the early formation of the earth's core. Its main the mass was probably formed more than 4 billion years ago, i.e., in the first hundreds of millions of years of the Earth’s existence. Ancient character surfaces of Mercury and the Moon and a number of indirect data on the structure of Mars and Venus do not contradict the concept early education nuclei of terrestrial planets. Data on the possible composition of the planets indicate that the formation of the cores of the terrestrial planets occurred as a result of the separation of iron-rich melt from silicates. The physical chemistry of the process of separating the iron melt and lowering it to the center of the planet has not been sufficiently studied. The heating of the planets during their growth was accompanied by the release of volatile components contained in the matter of the falling planetesimals. In the case of the Earth, water vapor condensed into the waters of the primordial pools, and the gases formed the atmosphere. According to isotope analysis (based on isotopes of iodine and xenon), basic. The mass of the Earth's atmosphere had accumulated by the time the planet's growth was completed. The composition of the ancient atmosphere is still poorly known.

Chemical process stratification of the earth's interior occurs in our time. Light melts in the form of magma rise from the mantle into the crust. They get partially stuck and freeze inside earth's crust, and partially break through the crust and pour out in the form of lava during the volcano. eruptions. Large-scale movements of matter in the subsurface caused by thermal convection and chemistry. differentiation, manifest themselves in the form of rises and falls of large areas of the surface, movement lithospheric plates, into which the earth’s crust is dissected, in the form of processes of volcanism and mountain building, as well as earthquakes (see. Seismology). About modern for the structure of the planetary interior, see Art. Planets and satellites.

Lit.: Protostars and planets, v, 1-2, Tucson, 1978-85; Safronov V, S., Vityazev A. V., Origin of the Solar System, in the book: Results of Science and Technology, ser. Astronomia, t., 24, M., 1983. A. V. Vityazev.

Physical encyclopedia. In 5 volumes. - M.: Soviet Encyclopedia. Chief Editor A. M. Prokhorov. 1988 .

OUR PLACE IN THE UNIVERSE

Nowadays people quite “easily” imagine their place in the boundless expanses of Space.
They have been moving towards such ideas for many thousands of years - from the first questioning glances of primitive man at the night sky of the Earth, to the creation the most powerful telescopes in all frequency ranges of EM vibrations.

Other types are now used to study the properties of outer space. wave processes (gravitational waves) and elementary particles (neutrino telescopes). Are used space scouts- interplanetary spacecraft, which continue their work outside the Solar System and bring information about our planet to those inhabitants of the Galaxy (Universe) who will become owners of these spacecraft in the future.

Studying nature (ancient Greek φύσις), humanity had to move from simple contemplation and philosophizing (natural philosophy) to the creation of a full-fledged science - physics - experimental and theoretical (G. Galileo). Physics was able to predict the future in the development of natural processes.

Physics at its core is the basis for all sciences, including mathematics, which cannot exist separately from nature, since it draws its themes from nature and is a tool for its study. As the mysteries of planetary motion were unraveled, new branches of mathematics were created (I. Newton, G. Leibniz), which are now used with great success in all areas of human activity without exception, including in the knowledge of the laws of the universe. Understanding these laws made it possible to determine our place in the Universe.

The process of cognition continues and cannot stop as long as a person and his natural curiosity exist - he wants to know what everything is made of and how it works (galaxies, stars, planets, molecules, atoms, electrons, quarks...), where everything comes from ( physical vacuum), where it disappears (black holes), etc. For this purpose, scientists are creating new physical and mathematical theories, for example, superstring theory(M – theory)
(E. Witten, P. Townsend, R. Penrose, etc.), who explain the structure of both Macro and Micro worlds.

So, our Galaxy (Milky Way) is part of the so-called local group of galaxies. The sizes of galaxies and the distances between them are enormous and require special units of measurement (see column on the right).

our neighbors from local group galaxies (enlarge picture)

Our Galaxy - the Milky Way - is a giant disk consisting of stars different types, star clusters, interstellar matter consisting of various types radiation, elementary particles, atoms and molecules, dark matter, the mystery of which astrophysicists are now struggling with. At the center of our Galaxy there is black hole(at least one) - another one of the astrophysical problems of our time.

The diagram below shows the structure of the Galaxy (arms, core, halo), its dimensions and the place occupied in it by the Sun, Earth and other planets - satellites of the Sun.

location of the solar system in the Milky Way Galaxy (diagram)
enlarge picture

diagram of sleeves (branches) milky way(Solar system highlighted)
enlarge picture

COSMOGONY(Greek κοσµογόνια from Greek κόσµος - order, peace, Universe and γονή - birth - origin of the world) - a section of astronomy devoted to the origin and development of celestial bodies.

ORIGIN OF THE SOLAR SYSTEM

A complete theory of the formation of the Solar System still does not exist. All hypotheses, starting with R. Descartes (1644), existed for a certain time, and when they could not explain some phenomena occurring in the Solar system, they were either rejected completely, or developed and supplemented by other scientists.

The first serious one cosmogonic hypothesis about the origin of the solar system was created and published in 1755 German philosopher Immanuel Kant (1724-1804), who believed that the Sun and planets were formed from solid particles of a huge cloud, which came closer and stuck together under the influence of mutual gravity.

The second cosmogonic hypothesis was put forward in 1796 by the French physicist and astronomer Pierre Simon Laplace (1749-1827). Taking the ring of Saturn as a gas ring, separated from the planet as it rotated around its axis, Laplace believed that the Sun arose from a gas nebula, the rotation speed of which increased as it compressed, and because of this, rings of gaseous matter (similar to the rings of Saturn) were separated from the Sun. that gave birth to the planets.

This hypothesis lasted for more than 100 years. However, like Kant's hypothesis, it was rejected because it did not explain the laws of the solar system. A reliable hypothesis should explain the following basic patterns of the Solar system:

1) the planets revolve around the Sun in almost circular orbits, slightly inclined to the plane of the Earth’s orbit, making an angle of 7° with the plane of the solar equator (the exception is the [dwarf] planet Pluto, whose orbit is inclined to the plane of the Earth’s orbit by 17°);

2) the planets revolve around the Sun in the direction of its rotation around its axis (from west to east), and most planets rotate in the same direction (the exception is Venus, Uranus and Pluto, rotating from east to west);

3) the mass of the Sun is 99.87% of the mass of the entire Solar System;

4) the product of the mass of each planet by its distance from the Sun and its orbital speed called the angular momentum of this planet; the product of the Sun's mass by its radius and linear rotation speed is the angular momentum of the Sun. IN total amount these products give the angular momentum of the Solar system, of which 98% is concentrated in the planets, and the Sun accounts for only 2%, i.e. The sun rotates very slowly ( linear speed its equator is 2 km/s);

5) physical properties Terrestrial planets and giant planets are different.

The hypotheses of Kant and Laplace could not explain all these patterns and were therefore rejected.
For example, Neptune is removed from the Sun at an average distance of d = 30 AU. and its linear orbital speed v = 5.5 km/s. Consequently, when the ring that gave birth to it separated, the Sun should have had the same radius and the same linear speed of its equator.
Contracting further, the Sun successively gave birth to other planets, and currently has a radius of R≈0.01 AU.
According to the laws of physics, the linear speed of the solar equator should be

those. much higher than the actual speed of 2 km/s. This example alone shows the inconsistency of Laplace's hypothesis.

At the beginning of the 20th century. Other hypotheses were put forward, but they all turned out to be untenable, since they could not explain all the basic laws of the Solar system.

According to modern concepts, the formation of the Solar System is associated with the formation of the Sun from a gas and dust environment. It is believed that the cloud of gas and dust from which the Sun was formed about 5 billion years ago rotated slowly. As it compressed, the speed of rotation of the cloud increased, and it took the shape of a disk. The central part of the disk gave rise to the Sun, and its outer regions gave rise to the planets. This scheme fully explains the difference in the chemical composition and masses of the terrestrial planets and the giant planets.

Indeed, as the Sun flared up, light chemical elements (hydrogen, helium) under the influence of radiation pressure left the central regions of the cloud, moving to its periphery. Therefore, the terrestrial planets were formed from heavy chemical elements with small admixtures of light ones and turned out to be small in size.

Due to the high density of gas and dust, solar radiation weakly penetrated to the periphery of the protoplanetary cloud, where low temperatures reigned and the incoming gases froze onto solid particles. Therefore, distant giant planets were formed large and mainly from light chemical elements.

This cosmogonic hypothesis explains a number of other regularities of the Solar system, in particular the distribution of its mass between the Sun (99.87%) and all the planets (0.13%), the current distances of the planets from the Sun, their rotation, etc.

It was developed in 1944-1949. Soviet academician Otto Yulievich Schmidt (1891-1956) and subsequently developed by his colleagues and followers.

3.Main steps geological history: evolution of the lithosphere, atmosphere, hydrosphere and living world.

3.1.Evolution of the lithosphere.
3.2.Evolution of the atmosphere.
3.3.Evolution of the hydrosphere.

1.Structure of the Universe and Solar System.

The universe or cosmos is the name given to everything around material world(Greek" space " -world). The universe is infinite in space and time. Matter in the universe is distributed unevenly and is represented by stars, planets, dust, meteorites, comets, gases. The part of the Universe accessible for study is called the Metagalaxy, which includes over a billion star clusters of galaxies (Greek."galaxy" - milky, milky).

Our Galaxy is called the Milky Way and is of the spiral type and includes over 150 billion stars. It is a wide whitish strip of stars. The age of the Galaxy is ~ 12 billion years.

The mass of the Sun is 99.87% of the total mass of the Galaxy (Jupiter is the largest planet -0.1%), so it is the center of gravity of all cosmic bodies. Physically, the Sun is a plasma ball. Chemical composition -70 elements; main ones: hydrogen and helium; average t° C ~5600 ° WITH; age -6-6.5 billion years. Thermal energy The sun is caused by thermonuclear processes of converting hydrogen into helium.

The heat and light emitted by the Sun have a great influence on geological processes. Continuous explosive activity on the Sun causes the formation of the so-called solar wind (the movement of charged particles in space), which is associated with the aurora and magnetic phenomena in the Earth's atmosphere.

The Solar System includes 9 planets, 42 satellites, about 50 thousand asteroids, many meteors and comets.

The orbits of the planets are located in the same plane, coinciding with the equatorial plane of the Sun and the direction of rotation around the Sun, except for Venus and Uranus, it is the opposite and coincides with the direction of rotation of the Sun around its axis.

2. Hypotheses of the origin of the Solar system and the Earth.

The German philosopher Emmanuel Casset in 1755 expressed the idea of ​​the origin of the Universe from primary matter, consisting of the smallest particles. The formation of stars, the Sun and other cosmic bodies, in his opinion, occurred under the influence of forces of attraction and repulsion under conditions of chaotic movement of particles. The French mathematician P. Laplace (1796) associated the formation of the solar system with the rotational movement of a rarefied and hot gaseous nebula, which led to the emergence of clumps of matter - the embryos of planets. According to the Kant-Laplace hypothesis, the initially hot Earth cooled and contracted, which led to deformation of the earth's crust.

According to the hypothesis of O. Yu. Schmidt (1943), the planetary system was formed from dust and meteoric matter when it entered the sphere of the Sun. The initially cold Earth and other planets gradually warmed up under the influence of radioactive decay energy, gravitational and other processes, and then cooled.

Soviet astronomer V. G. Fesenkov in the 50s proposed a solution to the problem from the point of view of the formation of the Sun and planets from general environment, resulting from the compaction of gas and dust matter. It was assumed that the Sun was formed from the central part of the condensation, and the planets from the outer parts.

According to modern concepts, the bodies of the Solar System were formed from primarily cold cosmic solid and gaseous matter through compaction and condensation until the formation of the Sun and proto-planets. Asteroids and Meteorites are considered the source material of planets Earth group(Mercury, Venus, Earth, and Mars are small in size; high density, low mass of the atmosphere, low speed of rotation around its axis); and comets and meteors are giant planets (Jupiter, Saturn, Uranus, Neptune, Pluto - huge in size, low density, dense atmosphere with H 2, Ge and methane, high rotation speed). The formation of modern shells of the Earth is associated with the processes of gravitational differentiation of the original homogeneous matter.

The most advanced hypothesis is to explain the origin of the Universe big bang theory. According to this theory, ~15 billion years ago, our Universe was compressed into a lump, billions of times smaller than the head of a pin. According to mathematical calculations, its diameter was equal and its density was close to infinity. This condition is called singular-infinite density in a point volume. The unstable initial state of matter led to an explosion, which gave rise to an abrupt transition to the expanding Universe.

The earliest stage in the development of the Universe is called inflationary-its period is up to 10 -33 seconds after the explosion. As a result, space and time arise. The size of the Universe is several times greater than the size of the modern one; there is no matter.

Next stage - hot. The ejection of a body is associated with the released energy when Big Bang. The radiation heated the Universe to 1027 K. Then came a period of cooling of the Universe for ~500 thousand years. As a result, a homogeneous Universe arose. The transition from homogeneous to structural occurred from 1 to 3 billion years.

3.Main stages of geological history: evolution of the lithosphere,

atmosphere, hydrosphere and living world.

The geological development of the Earth is characterized by the direction and irreversibility of all geological events, including tectonic ones, which led to the formation of modern complex structure lithosphere. Famous Russian tectonist V. E. Khain. Viktor Efimovich (b. 1914) in 1973 identified the stages of its development:

I. pre-geological (4.6 -4.5 billion years);

II. lunar; from the formation of the earth's crust to the formation of the hydrosphere (4.5 -4.0 billion years);

III. Katarchean, the primary continental lithosphere is formed, composing the cores of future continents (4.0 -3.5 billion years);

IV. Sub-Late Archean-Early Proterozoic or early geosynclinal: formation of proto-geosynclines and the first platforms (3.5 -2.0 billion years);

V. Middle Proterozoic - Early Riphean or Early Platform, consolidation of the primary continental crust, 2.0 -1.4 billion years;

VI. Late Proterozoic-Paleozoic or geosynclinal-platform; separation of ancient platforms and their development (1.4 -0.2 billion years);

VII. Mesozoic-Cenozoic or continental-oceanic; formation of modern continents, creation of young platforms on Paleozoic and early Mesozoic folded structures; formation of young oceans (0.2 billion years).

IN geological development In the last stages of the Earth's history, a certain direction is observed: the volume of the lithosphere and upper mantle is constantly increasing, as well as the size of stable plates, despite the tracing of the opposite process - oceanization due to the collapse and development of continental clouds.

The directional development of the lithosphere is characterized by cyclical processes that manifest themselves mainly in different territories. That. In the history of the Earth, certain stages in the development of the lithosphere are observed, during which tectonic processes lead to tectonic restructuring of some parts of the lithosphere and then others.

At the same time, in the history of the lithosphere, periods of intense tectonic deformations can be distinguished, during which mountain building occurs. This phenomenon is explained by the long-term accumulation of stress in the lithosphere and its subsequent release in the form of tectonic processes.

Stages of tectonogenesis.

Long periods, after which tectonic processes, incl. and mountain building, which manifest themselves most intensively, are called tectonic cycles or cycles (stages) of tectonogenesis. They are planetary in nature.

In the history of the Earth, 11 main cycles of tectonogenesis are distinguished: from the Early Archical to the Alpine (or Cenozoic) incomplete. In the Prelembrian they last 300-600 million years, in the Phalerozoic -140-170 million years, in the Cenozoic -80 million years.

Each tectonic cycle consists of two parts: long evolutionary development And short-term active tectonic deformations, which are accompanied by regional metamorphism and mountain building.

The final part of the cycle is called folding era, which is characterized by the end of the development of individual geosynclinal systems and their transformation into an epigeosynclinal orogen, after which a plate form develops or extra-geosynclinal mountain structures are formed.

For evolutionary stages characteristic:

— long-term subsidence of geos (mobile) areas and the accumulation of thick sedimentary and sedimentary-volcanic strata in them;

— leveling of land relief (destruction of mountains, planar washout from platform plains, etc.);

— extensive subsidence of the edges of platforms adjacent to geosynclinal areas, their flooding with the waters of epicontinental seas;

- alignment climatic conditions, which is associated with widespread shallow dark epicontinental seas and humidification of the climate of the continents; solar energy is accumulated in the lower layers of the atmosphere; domains of definition disappear;

— the emergence of favorable conditions for life and wide distribution of fauna and flora.

These stages of the evolutionary development of the Earth are called thalasocratic. They are characterized by widespread development of marine sediments, development of vegetation, etc. Formation of coal deposits, rapid development life in the seas, formation of oil and gas bearing strata, carb. Rocks in warm seas.

Epochs of folding and mountain building has the following features:

- widespread development of mountain-building movements in geos. areas of oscillatory movements on platforms;

— manifestation of powerful intrusive and then effusive magmatism;

— raising of the edges of platforms adjacent to epiogeosynclinal areas, regression of epicontinental seas and complication of land reliefs;

- continentalization of climates, calming climatic conditions, increasing zonality, expansion of deserts and the appearance of areas of continental glaciation (in the mountains and near platforms).

- deterioration of conditions for the development of the organic world, resulting in the extinction of dominant and highly specialized forms and the emergence of new ones.

The conditions of these folding epochs are called geocratic, those. stages of relative increase in land mass.

Continental deposits are developed on Earth with frequent red-colored formations (sometimes carbonic, gypsum and saline), having a diverse genesis (formation in deserts, lagoons, brackish or fresh lakes, river deltas, on plains and foothills).

3.2.Evolution of the atmosphere

The atmosphere was not always modern composition and structure. The primary helium-hydrogen atmosphere was lost by the Earth during heating. From the substance that formed the planet, during its formation, various gases. This happened especially intensively during tectonic activity: during the formation of cracks and faults.

It is likely that the atmosphere and hydrosphere did not separate immediately. For some time, the Earth was enveloped by a thick layer of water vapor and gases (CO, CO 2, HF, H 2, S, NH 3, CH 4); low-permeable to sunlight. This shell had a temperature of ~ +100 ° C. With a decrease in temperature, this shell was divided into the atmosphere and the hydrosphere. There was no free oxygen in this atmosphere. It had to be released from earthly matter and was formed due to the multiplication of water vapor molecules, but was spent on oxidation processes. Due to the lack of ozone, the atmosphere did not protect the Earth from short-wave radiation from the Sun. A significant number of hydrogen compounds on Earth are the consequences of its predominance in the primary atmosphere.

Volcanic processes enriched the atmosphere with carbon dioxide. It took long time, before absorption occurs as a result of reaction with other elements and photosynthesis large quantity carbon from the atmosphere. At the end of the PZ, the composition of the atmosphere as a whole was no longer much different from the modern one: it became nitrogen-oxygen. The composition of the modern atmosphere is the same as in the early geological epochs regulated by organisms.

The atmosphere is in continuous interaction with other shells of the Earth, exchanging matter and energy, and is constantly influenced by Space and the Sun.

3.3.Evolution of the hydrosphere.

Hydrosphere - the water shell of the Earth, including chemically unbound water, regardless of its state: liquid, solid, gaseous.

Earth is the most watery planet in the solar system: more than 70% of its surface is covered by the waters of the World Ocean.

Probably, the hydrosphere was formed simultaneously with the lithosphere and atmosphere as a result of cooling and degassing of mantle matter. Chemically bound water was already in the substance of the cold gas-dust protoplanetary cloud. Under the influence of the deep heat of the Earth, it was released and moved to the surface of the Earth. The primordial ocean may have covered almost the entire Earth, but it was not deep. Ocean water, probably was warm, highly mineralized. The ocean deepened and its area decreased. Moisture evaporated from the surface of the Ocean and heavy rain fell.

Fresh water on land - the result of passing ocean water through the atmosphere. The release of water from magma continues to this day. Volcanic eruptions release an average of 1,310 8 tons of water per year. Thermal springs and fumaroles carry 10 8 tons.

If we assume that the flow of water from the mantle into the lithosphere and onto its surface was uniform and amounted to only 0.00011 g per year per 1 cm 2 of the planet’s surface, then this is enough for the hydrosphere to form during the existence of the Earth.

It is also assumed that water comes from space as a result of icy comet nuclei falling to Earth, but its amount in this case is small.

The hydrosphere also loses water by evaporating it into space, where, under the influence of ultraviolet rays, H 2 O breaks down into H 2 and O 2.

3.4.Evolution of the animal world (biosphere).

The active interaction of the atmosphere, hydrosphere and lithosphere with the participation of solar energy and internal heat of the Earth was the most important prerequisite for the emergence of life.

Data from paleontological studies suggest that the most primitive organisms were formed from protein structures at the end of AR 1 (i.e. ~3 billion years ago). First single-celled organisms, capable of photosynthesis, arose about 2.7 billion years ago, and the first multicellular animals - no less than 1-1.5 billion years later.

In the absence of an ozone screen, the places where life developed were probably the coastal parts of the seas and inland bodies of water, to the bottom of which the sunlight, and the water did not transmit violet radiation. The compounds formed multimolecular systems that interact with the environment.

During evolution, they acquired the properties of living organisms: reproduction, metabolism, growth, etc.

The aquatic environment promoted metabolism and was a support for organisms without skeletons. The first living organisms appeared in a warm and humid climate (at equatorial latitude), since temperature fluctuations were detrimental to nascent life.

Long time life « was located » V geographical envelope spots, « ple nka life » was very intermittent. Over time, the mass of living matter rapidly increased, life forms became more complex and diverse, the areas of its distribution expanded, and relationships with other components of the geographic envelope became more complex.

The wide and rapid spread of life on Earth was facilitated by adaptability to the environment and the ability to reproduce.

For many centuries, the question of the origin of the Earth remained the monopoly of philosophers, since factual material in this area was almost completely absent. 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, corresponding to the growth of our cosmogonic ideas.

According to modern concepts, the formation of the Solar System began about 4.6 billion years ago with the gravitational collapse of a small part of a giant interstellar molecular cloud. Most of the matter ended up in the gravitational center of collapse with the subsequent formation of a star - the Sun. The matter that did not fall into the center formed a protoplanetary disk rotating around it, from which the planets, their satellites, asteroids and other small bodies of the Solar System were subsequently formed.

Theories of the origin of the solar system

Nebular hypothesis of Kant-Laplace. According to natural scientific views philosopher I. Kant, orbital motion planets arose “after an off-central impact of particles as a mechanism for the emergence of the primary nebula” ( wrong assumption, since the movement could only begin with an oblique impact of the nebulae). He considered the reasons counteracting the desire for “equilibrium” to be chemical processes inside the Earth, which depend on Space Force and manifest themselves in the form of earthquakes and volcanic activity (1755).

Tidal or planetesimal hypothesis. In the 20th century American astrophysicists T. Chamberlain and F. Multon considered the idea of ​​a meeting of the Sun with a star, which caused a tidal ejection of solar matter (1906), from which the planets were formed.

The hypothesis of the capture of interstellar gas by the Sun. It was suggested by the Swedish astrophysicist X. Alfen (1942). The gas atoms were ionized when falling on the Sun and began to move in orbits in its magnetic field, entering certain areas of the equatorial plane.

Academician-astrophysicist V.G. Fesenkov (1944) suggested that the formation of planets is associated with the transition from one type of nuclear reactions in the depths of the Sun to another.

Astronomer and mathematician J. Darwin and mathematician A.M. Lyapunov (40s of the XX century) independently calculated the equilibrium figures of a rotating liquid incompressible mass.

According to the views of O. Struve, an English astrophysicist (40s of the 20th century), rapidly rotating stars can eject matter in the plane of their equators. As a result, gas rings and shells are formed, and the star loses mass and angular momentum.

Currently, the theory of the formation of a planetary system in four stages is generally accepted. A planetary system is formed from the same protostellar dust material as the star, and at the same time. The initial compression of a protostellar dust cloud occurs when it loses stability. The central part contracts on its own and turns into a protostar. Another part of the cloud, with a mass about ten times less than the central part, continues to slowly rotate around the central thickening, and at the periphery, each fragment is compressed independently. At the same time, the initial turbulence, the chaotic movement of particles, subsides. The gas condenses into solid, bypassing the liquid phase. Larger solid dust grains - particles - are formed.

The larger the grains formed, the faster they fall to the central part of the dust cloud. The part of the substance that has an excess torque forms a thin gas-dust layer - a gas-dust disk. A protoplanetary cloud—a dust subdisk—is formed around the protostar. The protoplanetary cloud becomes more and more flat and becomes very dense. Due to gravitational instability, separate small cold clumps are formed in the dust subdisk, which, colliding with each other, form increasingly massive bodies - planetesimals. During the formation of a planetary system, some planetesimals were destroyed as a result of collisions, and some merged. A swarm of preplanetary bodies about 1 km in size is formed, the number of such bodies is very large - billions.

Then the preplanetary bodies combine to form planets. The accumulation of planets continues for millions of years, which is very insignificant compared to the lifetime of a star. The protosun is getting hot. Its radiation heats the inner region of the protoplanetary cloud to 400 K, forming an evaporation zone. Under the influence of the solar wind and light pressure, light chemical elements (hydrogen and helium) are pushed out of the vicinity of the young star. In a distant region, at a distance of over 5 AU, a freezing zone with a temperature of approximately 50 K is formed. This leads to differences in the chemical composition of future planets.

At the center of the solar system, less than massive planets. Here sunny wind blew out fine particles and gas. But heavier particles, on the contrary, tended to the center. The growth of the Earth continued for hundreds of millions of years. Its depths warmed up to 1000-2000 K due to gravitational compression and large bodies (up to hundreds of kilometers in diameter) participating in the accumulation. The fall of such bodies was accompanied by the formation of craters with pockets of increased temperature underneath them. Another and main source of the Earth's heat is the decay of radioactive elements, mainly uranium, thorium and potassium. Currently, the temperature in the center of the Earth reaches 5000 K, which is much higher than at the end of accumulation. Solar tides slowed down the rotation of planets close to the Sun - Mercury and Venus. With the advent of radiological methods, the age of the Earth, Moon and Solar System was accurately determined - about 4.6 billion years. The sun has existed for 5 billion years and will emit an almost constant flow of energy for the same amount of time due to the nuclear reactions occurring in its depths. Then, in accordance with the laws of stellar evolution, the Sun will turn into a red giant, and its radius will increase significantly, becoming more orbit Earth.