A scientific approach to the question of the origin of the Earth and the solar system became possible after the strengthening in science of the idea of material unity in the Universe. There is a science about the origin and development of celestial bodies - cosmogony.
The first attempts to give a scientific justification for the question of the origin and development of the solar system were made 200 years ago.
All hypotheses about the origin of the Earth can be divided into two main groups: nebular (Latin "nebula" - fog, gas) and catastrophic. The first group is based on the principle of the formation of planets from gas, from dust nebulae. The second group is based on various catastrophic phenomena (collision of celestial bodies, close passage of stars from each other, etc.).
One of the first hypotheses was expressed in 1745 by the French naturalist J. Buffon. According to this hypothesis, our planet was formed as a result of the cooling of one of the clots of solar matter ejected by the Sun during its catastrophic collision with a large comet. The idea of J. Buffon about the formation of the Earth (and other planets) from plasma was used in a whole series of later and more advanced hypotheses of the "hot" origin of our planet.
Nebular theories. Hypothesis of Kant and Laplace
Among the nebular theories, of course, the leading place is occupied by the hypothesis developed by the German philosopher I. Kant (1755). Independently of him, another scientist - the French mathematician and astronomer P. Laplace - came to the same conclusions, but developed the hypothesis more deeply (1797). Both hypotheses are similar in essence and are often considered as one, and its authors are considered the founders of scientific cosmogony.
The Kant-Laplace hypothesis belongs to the group of nebular hypotheses. According to their concept, a huge gas-dust nebula was previously located on the site of the solar system (a dust nebula of solid particles, according to I. Kant; a gas nebula, according to P. Laplace). The nebula was hot and spinning. Under the influence of the laws of gravity, its matter gradually condensed, flattened, forming a nucleus in the center. This is how the primordial sun was formed. Further cooling and compaction of the nebula led to an increase in the angular velocity of rotation, as a result of which, at the equator, the outer part of the nebula separated from the main mass in the form of rings rotating in the equatorial plane: several of them formed. As an example, Laplace cited the rings of Saturn.
Unevenly cooling, the rings were broken, and due to the attraction between the particles, the formation of planets circulating around the Sun took place. The cooling planets were covered with a hard crust, on the surface of which geological processes began to develop.
I. Kant and P. Laplace correctly noted the main and characteristic features of the structure of the solar system:
- 1) the vast majority of the mass (99.86%) of the system is concentrated in the Sun;
- 2) the planets circulate in almost circular orbits and almost in the same plane;
- 3) all planets and almost all their satellites rotate in the same direction, all planets rotate around their axis in the same direction.
A significant merit of I. Kant and P. Laplace was the creation of a hypothesis, which was based on the idea of the development of matter. Both scientists believed that the nebula had a rotational motion, as a result of which the particles were compacted and the planets and the Sun were formed. They believed that motion is inseparable from matter and is as eternal as matter itself.
The Kant-Laplace hypothesis has existed for almost two hundred years. Subsequently, it was proved to be inconsistent. So, it became known that the satellites of some planets, such as Uranus and Jupiter, rotate in a different direction than the planets themselves. According to modern physics, the gas separated from the central body must dissipate and cannot form into gas rings, and later - into planets. Other significant shortcomings of the hypothesis of Kant and Laplace are the following: the nebular catastrophic origin of the earth
- 1. It is known that the angular momentum in a rotating body always remains constant and is distributed evenly throughout the body in proportion to the mass, distance and angular velocity of the corresponding part of the body. This law also applies to the nebula from which the sun and planets formed. In the solar system, the momentum does not correspond to the law of distribution of momentum in a mass that has arisen from a single body. The planet of the solar system concentrates 98% of the angular momentum of the system, and the Sun has only 2%, while the Sun accounts for 99.86% of the entire mass of the solar system.
- 2. If we add the moments of rotation of the Sun and other planets, then in the calculations it turns out that the primary Sun rotated at the same speed as Jupiter now rotates. In this regard, the Sun must have had the same contraction as Jupiter. And this, as calculations show, is not enough to cause fragmentation of the rotating Sun, which, according to Kant and Laplace, disintegrated due to excess rotation.
- 3. At present, it has been proven that a star with an excess of rotation breaks up into parts, and does not form a family of planets. Spectral binary and multiple systems can serve as an example.
According to US geochemists, the collision of the Earth with the celestial body Theia, which supposedly occurred about 4.5 billion years ago, if it took place, did not make major changes in the structure of the bowels. At least, our planet did not exactly turn into a hot ball.
The modern hypothesis of the origin of the Earth is still the subject of heated cabinet debate, but most scientists agree that everything began from a protoplanetary cloud of cosmic dust and gas. Some scientists were sure that it was cold, others that, on the contrary, it was red-hot, since it was pulled out of the young Sun by the gravity of a massive star passing nearby at that time. The latest version is rapidly losing its fans today, since astrophysicists have proven that such an interpretation of events is extremely unlikely. Therefore, today the hypothesis of a cold protoplanetary cloud dominates.
Approximately 4.54 billion years ago, the Earth began to form from this protoplanetary cloud. The process itself probably took place as follows: since in this cloud the “light” and “heavy” elements were not yet strongly mixed, as a result of the action of gravity, the second (iron and other related metals) began to descend towards the future center of the planet, squeezing out on surface more "light" elements. Scientists called this process gravitational differentiation.
Thus, iron accumulated in the center of the cloud, forming the future core. But during the lowering, the potential energy of the layer of "heavy" elements began to decrease, respectively, the kinetic energy began to increase, that is, heating occurred. It is believed that this heat warmed up our planet to 1200 degrees Celsius (in some places - up to 1600 degrees).
However, the impact of the most perfect refrigerator in nature - space, led to the fact that the surface of the cloud of "light" elements began to cool rapidly, turning from a melt into a solid. This is how the earth's crust was formed. And the area where gravitational differentiation continued (according to the calculations of some geophysicists, this process will continue for about one and a half billion years), and the high temperature was preserved, became the modern mantle.
Approximately 4.5 billion years ago, the solid part of the Earth was fully formed (although the atmosphere and hydrosphere appeared somewhat later). And it was at that time, according to recent research, that a catastrophe occurred, the result of which was the appearance of a satellite and a return to an unstructured state. According to many scientists, most likely, there was a collision with some massive celestial body (named the planet Theia).
At the same time, some geophysicists are sure that the collision was so impressive that the upper part of the Earth melted again. That is, for some time the planet was a ball of molten homogeneous substance, after which, over several tens of millions of years, it again acquired a solid surface.
Yet some scientists have expressed doubt that the consequences of this collision were so significant. They are sure that even a collision with a celestial body could not radically change the existing structure of our planet. More recently, this version has received evidence of its plausibility. And this evidence was presented by stones discovered near Kostomuksha.
It arose about 4600 million years ago. Since then, its surface has constantly changed under the influence of various processes. The earth apparently formed several million years after a colossal explosion in space. The explosion created huge gas and dust. Scientists believe that its particles, colliding with each other, combined into giant clumps of hot matter, which eventually turned into the current planets.
According to scientists, the Earth arose after a colossal cosmic explosion. The first continents probably formed from molten rock flowing to the surface from vents. Freezing, it made the earth's crust thicker. Oceans could form in the lowlands from droplets contained in volcanic gases. The original one probably consisted of the same gases.
It is thought that the Earth was incredibly hot at first, with a sea of molten rock on the surface. Approximately 4 billion years ago, the Earth began to slowly cool and split into several layers (see right). The heaviest rocks sank deep into the bowels of the Earth and formed its core, remaining unimaginably hot. The less dense matter formed a series of layers around the core. On the surface itself, the molten rocks gradually solidified, forming a solid earth's crust, covered with many volcanoes. The molten rock, breaking out to the surface, froze, forming the earth's crust. The low areas were filled with water.
Earth today
Although the earth's surface seems solid and unshakable, changes are still taking place. They are caused by various kinds of processes, some of which destroy the earth's surface, while others recreate it. Most of the changes proceed extremely slowly and are detected only by special instruments. It takes millions of years to form a new mountain range, but a powerful volcanic eruption or a monstrous earthquake can transform the surface of the Earth in a matter of days, hours and even minutes. In 1988, an earthquake in Armenia that lasted about 20 seconds destroyed buildings and killed more than 25,000 people.
Earth structure
In general, the Earth has the shape of a ball, slightly flattened at the poles. It consists of three main layers: crust, mantle and core. Each layer is formed by different types of rocks. The figure below shows the structure of the Earth, but the layers are not drawn to scale. The outer layer is called the earth's crust. Its thickness is from 6 to 70 km. Under the crust is the upper layer of the mantle, formed by solid rocks. This layer, together with the crust, is called and has a thickness of about 100 km. The part of the mantle that lies beneath the lithosphere is called the asthenosphere. It is about 100 km thick and probably consists of partially molten rocks. The mantle changes from 4000°C near the core to 1000°C in the upper part of the asthenosphere. The lower mantle may be composed of hard rocks. The outer core consists of iron and nickel, apparently molten. The temperature of this layer can reach 55 STGS. The temperature of the sub-core can be over 6000'C. It is solid due to the colossal pressure of all other layers. Scientists believe that it consists mainly of iron (more on this in the article "").
The history of our planet still holds many mysteries. Scientists from various fields of natural science have contributed to the study of the development of life on Earth.
It is believed that the age of our planet is about 4.54 billion years. This entire time period is usually divided into two main stages: Phanerozoic and Precambrian. These stages are called eons or eonoteme. Eons, in turn, are divided into several periods, each of which is distinguished by a set of changes that have taken place in the geological, biological, atmospheric state of the planet.
- Precambrian, or Cryptozoic- this is an eon (time interval of the development of the Earth), covering about 3.8 billion years. That is, the Precambrian is the development of the planet from the moment of formation, the formation of the earth's crust, the proto-ocean and the emergence of life on Earth. By the end of the Precambrian, highly organized organisms with a developed skeleton were already widespread on the planet.
The eon includes two more eonotemes - katarche and archaea. The latter, in turn, includes 4 eras.
1. Katarchaeus- this is the time of the formation of the Earth, but there was still neither the core nor the earth's crust. The planet was still a cold cosmic body. Scientists suggest that during this period there was already water on Earth. The Catarchean lasted about 600 million years.
2. Archaea covers a period of 1.5 billion years. During this period, there was no oxygen on Earth yet, deposits of sulfur, iron, graphite, and nickel were being formed. The hydrosphere and the atmosphere were a single vapor-gas shell that enveloped the globe in a dense cloud. The sun's rays practically did not penetrate through this veil, so darkness reigned on the planet. 2.1 2.1. Eoarchean- this is the first geological era, which lasted about 400 million years. The most important event of the Eoarchean is the formation of the hydrosphere. But there was still little water, the reservoirs existed separately from each other and did not yet merge into the world ocean. At the same time, the earth's crust becomes solid, although asteroids are still bombarding the Earth. At the end of the Eoarchean, the first supercontinent in the history of the planet, Vaalbara, is formed.
2.2 Paleoarchaean- the next era, which also lasted approximately 400 million years. During this period, the core of the Earth is formed, the magnetic field strength increases. A day on the planet lasted only 15 hours. But the oxygen content in the atmosphere increases due to the activity of bacteria that have appeared. The remains of these first forms of the Paleoarchean era of life have been found in Western Australia.
2.3 Mesoarchean also lasted about 400 million years. In the Mesoarchean era, our planet was covered by a shallow ocean. Land areas were small volcanic islands. But already during this period, the formation of the lithosphere begins and the mechanism of plate tectonics starts. At the end of the Mesoarchean, the first ice age occurs, during which snow and ice form for the first time on Earth. Biological species are still represented by bacteria and microbial life forms.
2.4 Neoarchean- the final era of the Archean eon, the duration of which is about 300 million years. Colonies of bacteria at this time form the first stromatolites (limestone deposits) on Earth. The most important event of the Neoarchean is the formation of oxygen photosynthesis.
II. Proterozoic- one of the longest time periods in the history of the Earth, which is usually divided into three eras. During the Proterozoic, the ozone layer first appears, the world ocean reaches almost its present volume. And after the longest Huron glaciation, the first multicellular life forms appeared on Earth - mushrooms and sponges. The Proterozoic is usually divided into three eras, each of which contained several periods.
3.1 Paleo-Proterozoic- the first era of the Proterozoic, which began 2.5 billion years ago. At this time, the lithosphere is fully formed. But the former forms of life, due to the increase in oxygen content, practically died out. This period is called the oxygen catastrophe. By the end of the era, the first eukaryotes appear on Earth.
3.2 Mesoproterozoic lasted approximately 600 million years. The most important events of this era: the formation of continental masses, the formation of the supercontinent Rodinia and the evolution of sexual reproduction.
3.3 Neo-proterozoic. During this era, Rodinia breaks up into about 8 parts, the super-ocean of Mirovia ceases to exist, and at the end of the era, the Earth is covered with ice almost to the equator. In the Neoproterozoic era, living organisms for the first time begin to acquire a hard shell, which will later serve as the basis of the skeleton.
III. Paleozoic- the first era of the Phanerozoic eon, which began approximately 541 million years ago and lasted about 289 million years. This is the era of the emergence of ancient life. The supercontinent Gondwana unites the southern continents, a little later the rest of the land joins it and Pangea appears. Climatic zones begin to form, and flora and fauna are represented mainly by marine species. Only towards the end of the Paleozoic does the development of land begin, and the first vertebrates appear.
The Paleozoic era is conditionally divided into 6 periods.
1. Cambrian period lasted 56 million years. During this period, the main rocks are formed, the mineral skeleton appears in living organisms. And the most important event of the Cambrian is the appearance of the first arthropods.
2. Ordovician period- the second period of the Paleozoic, which lasted 42 million years. This is the era of the formation of sedimentary rocks, phosphorites and oil shale. The organic world of the Ordovician is represented by marine invertebrates and blue-green algae.
3. Silurian period covers the next 24 million years. At this time, almost 60% of living organisms that existed before die out. But the first cartilaginous and bone fish in the history of the planet appear. On land, the Silurian is marked by the appearance of vascular plants. Supercontinents converge and form Laurasia. By the end of the period, ice melting was noted, the sea level rose, and the climate became milder.
4 Devonian is characterized by the rapid development of various forms of life and the development of new ecological niches. Devon covers a time interval of 60 million years. The first terrestrial vertebrates, spiders, and insects appear. Land animals develop lungs. Although fish still dominate. The kingdom of flora of this period is represented by ferns, horsetails, club mosses and gosperms.
5. Carboniferous period often referred to as carbon. At this time, Laurasia collides with Gondwana and the new supercontinent Pangea appears. A new ocean is also formed - Tethys. This is the time when the first amphibians and reptiles appeared.
6. Permian period- the last period of the Paleozoic, which ended 252 million years ago. It is believed that at this time a large asteroid fell to Earth, which led to significant climate change and the extinction of almost 90% of all living organisms. Most of the land is covered with sand, the most extensive deserts appear that have only existed in the entire history of the Earth's development.
IV. Mesozoic- the second era of the Phanerozoic eon, which lasted almost 186 million years. At this time, the continents acquire almost modern outlines. A warm climate contributes to the rapid development of life on Earth. Giant ferns disappear, and angiosperms appear to replace them. The Mesozoic is the era of dinosaurs and the appearance of the first mammals.
The Mesozoic era is divided into three periods: Triassic, Jurassic and Cretaceous.
1. Triassic period lasted a little over 50 million years. At this time, Pangea begins to split, and the inland seas gradually become smaller and dry up. The climate is mild, the zones are not pronounced. Nearly half of land plants are disappearing as deserts spread. And in the realm of fauna, the first warm-blooded and terrestrial reptiles appear, which became the ancestors of dinosaurs and birds.
2 Jurassic covers a gap of 56 million years. A humid and warm climate reigned on Earth. The land is covered with thickets of ferns, pines, palms, cypresses. Dinosaurs reign on the planet, and numerous mammals have so far been distinguished by their small stature and thick hair.
3 Cretaceous- the longest period of the Mesozoic, lasting almost 79 million years. The split of the continents is practically coming to an end, the Atlantic Ocean is significantly increasing in volume, and ice sheets are forming at the poles. An increase in the water mass of the oceans leads to the formation of a greenhouse effect. At the end of the Cretaceous, a catastrophe occurs, the causes of which are still not clear. As a result, all dinosaurs and most species of reptiles and gymnosperms became extinct.
V. Cenozoic- this is the era of animals and Homo sapiens, which began 66 million years ago. The continents at this time acquired their modern shape, Antarctica occupied the south pole of the Earth, and the oceans continued to grow. Plants and animals that survived the catastrophe of the Cretaceous period found themselves in a completely new world. Unique communities of lifeforms began to form on each continent.
The Cenozoic era is divided into three periods: Paleogene, Neogene and Quaternary.
1. Paleogene period ended approximately 23 million years ago. At that time, a tropical climate reigned on Earth, Europe was hiding under evergreen tropical forests, and deciduous trees grew only in the north of the continents. It was during the Paleogene period that the rapid development of mammals takes place.
2. Neogene period covers the next 20 million years of the planet's development. Whales and bats appear. And, although saber-toothed tigers and mastodons still roam the earth, the fauna is increasingly acquiring modern features.
3. Quaternary period began more than 2.5 million years ago and continues to this day. Two major events characterize this time period: the Ice Age and the advent of man. The Ice Age completely completed the formation of the climate, flora and fauna of the continents. And the appearance of man marked the beginning of civilization.
1. Introduction …………………………………………………2 p.
2. Hypotheses of the formation of the Earth………………………...3 - 6 pp.
3. The internal structure of the Earth…………………………7 - 9 pp.
4. Conclusion……………………………………………… 10 p.
5. References …………………………………..11 p.
Introduction.
At all times, people have wanted to know where and how the world we live in originated. There are many legends and myths that came from ancient times. But with the advent of science in its modern sense, mythological and religious ideas are being replaced by scientific ideas about the origin of the world.
At present, a situation has arisen in science that the development of a cosmogonic theory and the restoration of the early history of the solar system can be carried out mainly inductively, based on a comparison and generalization of recently obtained empirical data on the material of meteorites, planets and the Moon. Since a lot has become known about the structure of atoms and the behavior of their compounds under various thermodynamic conditions, and absolutely reliable and accurate data have been obtained about the composition of cosmic bodies, the solution to the problem of the origin of our planet is placed on a solid chemical basis, which the previous cosmogonic constructions were deprived of. It should be expected in the near future that the solution of the problems of the cosmogony of the solar system in general and the problem of the origin of our Earth in particular will achieve great success at the atomic-molecular level, just as at the same level the genetic problems of modern biology are being brilliantly solved before our very eyes.
In the current state of science, a physicochemical approach to solving the problems of the cosmogony of the solar system is absolutely inevitable. Therefore, the long-known mechanical features of the solar system, to which the classical cosmogonic hypotheses paid the main attention, must be interpreted in close connection with the physicochemical processes in the early history of the solar system. Recent achievements in the field of chemical study of individual bodies of this system allow us to take a completely new approach to the restoration of the history of the Earth's substance and, on this basis, restore the framework of the conditions in which our planet was born - the formation of its chemical composition and the formation of the shell structure.
Thus, the purpose of this work is to tell about the most famous hypotheses of the formation of the Earth, as well as about its internal structure.
Hypotheses of the formation of the Earth.
At all times, people have wanted to know where and how the world we live in originated. There are many legends and myths that came from ancient times. But with the advent of science in its modern sense, mythological and religious ideas are being replaced by scientific ideas about the origin of the world. 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.
All hypotheses about the origin of the Earth can be divided into two main groups:
1. Nebular (Latin "nebula" - fog, gas) - the basis is the principle of the formation of planets from gas, from dust nebulae;
2. Catastrophic - based on the principle of the formation of planets due to various catastrophic phenomena (collision of celestial bodies, close passage of stars from each other, etc.).
Nebular hypotheses of Kant and Laplace. The first scientific hypothesis about the origin of the solar system was that of Immanuel Kant (1755). 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.
Independently of Kant, another scientist - the French mathematician and astronomer P. Laplace - came to the same conclusions, but developed the hypothesis more deeply (1797). 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. Satellites of individual planets were formed from the substance of 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. Both theories are essentially similar to each other and are often considered as one, mutually complementing each other, therefore in the literature they are often referred to under the general name of the Kant-Laplace hypothesis. Since science did not have more acceptable explanations at that time, this theory had many followers in the 19th century.
Jeans catastrophic theory. After the Kant-Laplace hypothesis in cosmogony, several more hypotheses for the formation of the solar system were created. So-called catastrophic hypotheses appear, which are based on an element of random coincidence. As an example of the catastrophic direction hypothesis, consider the concept of the English astronomer Jeans (1919). His hypothesis is based on the possibility of another star passing near the Sun. Under the influence of its attraction, a jet of gas escaped from the Sun, which, with further evolution, turned into the planets of the solar system. Jeans believed that the passage of a star past the Sun made it possible to explain the discrepancy in the distribution of mass and angular momentum in the solar system. But in 1943 The Russian astronomer N. I. Pariysky calculated that only in the case of a strictly defined star speed could a gas clot become a satellite of the Sun. In this case, its orbit should be 7 times smaller than the orbit of the planet closest to the Sun - Mercury.
Thus, the Jeans hypothesis could not give a correct explanation for the disproportionate distribution of angular momentum in the solar system. The biggest drawback of this hypothesis is the fact of randomness, which contradicts the materialistic worldview and the available facts that speak of the location of planets in other stellar worlds. In addition, calculations have shown that the approach of stars in world space is practically impossible, and even if this happened, a passing star could not give the planets motion in circular orbits.
The Big Bang Theory. The theory, which is followed by most modern scientists, states that the Universe was formed as a result of the so-called Big Bang. An incredibly hot fireball, the temperature of which reached billions of degrees, at some point exploded and scattered flows of energy and particles of matter in all directions, giving them tremendous acceleration. Since the fireball shattered into pieces as a result of the Big Bang had an enormous temperature, the tiny particles of matter had too much energy at first and could not combine with each other to form atoms. However, after about a million years, the temperature of the Universe dropped to 4000 "C, and various atoms began to form from elementary particles. First, the lightest chemical elements - helium and hydrogen, formed, their accumulation formed. Gradually, the Universe cooled more and more and heavier elements were formed. During for many billions of years there has been an increase in masses in accumulations of helium and hydrogen.The growth of mass goes on until a certain limit is reached, after which the force of mutual attraction of particles inside the gas and dust cloud is very strong and then the cloud begins to compress (collapse).During the collapse, high pressure develops inside the cloud, conditions favorable for the reaction of thermonuclear fusion - the fusion of light hydrogen nuclei with the formation of heavy elements. A star is born in place of the collapsing cloud. As a result of the birth of a star, more than 99% of the mass of the initial cloud is in the body of the star, and the rest form scattered clouds of solid particles from which planets are subsequently formed star system.
Modern theories. In recent years, a number of new hypotheses have been put forward by American and Soviet scientists. If earlier it was believed that a continuous process of heat transfer took place in the evolution of the Earth, 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 is the "dust cloud theory" by the American astronomer F. L. Wiple (1948). However, in essence, this is nothing more than a modified version of the nebular theory of Kant-Laplace. Also popular are the hypotheses of Russian scientists O.Yu. Schmidt and V.G. Fesenkov. Both scientists, when developing their hypotheses, proceeded from the ideas about the unity of matter in the Universe, about the continuous movement and evolution of matter, which are its main properties, about the diversity of the world, due to various forms of the existence of matter.
Curiously, at a new level, armed with better 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.
