School encyclopedia. When and how the earth's message was formed as the earth appeared

The story of our planet still keeps a lot of mysteries. Scientists of different areas of natural science invested their contribution 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. All this time interval is made to divide into two main stages: plywood and doxcr. These stages are called eoan or eonotable. The aons in turn are divided into several periods, each of which is distinguished by a set of changes in the geological, biological, atmospheric state of the planet.

1. Precambria, or Cryptose - This is Eon (temporary land development interval), covering about 3.8 billion years. That is, Precambria is the development of the planet from the moment of formation, the formation of the earth's crust, the protoocyan and the emergence of life on earth. By the end of the Precambrian on the planet, high-organized organisms with a developed skeleton were already widespread.

The Eon includes two more eonothemes - Qatarhai and Archey. The latter, in turn, includes 4 eras.

1. Qatarhey - this is the time of the formation of the Earth, but there was no nor or earthly crust. The planet was still a cold cosmic body. Scientists suggest that during this period there were already water on Earth. Qatarhey lasted about 600 million years.

2. Archey covers a period of 1.5 billion years. During this period, there were no oxygen on Earth, there was a formation of sulfur, iron, graphite, nickel deposits. The hydrosphere and the atmosphere were a single vapor-gas shell, which covered the globe with a dense cloud. The sun's rays through this veil almost did not penetrate, so darkness reigned on the planet. 2.1 2.1. Eoarhey - This is the first geological era, which lasted about 400 million years. The most important event of EaChea is the formation of the hydrosphere. But there were still few water, the reservoirs existed separately from each other and have not yet merged into the world ocean. At the same time, the earth's bark becomes hard, although the asteroids are still bombarded. On the outcome of Eoarhey, the first in the history of the planet's supercontinent - Vaalbara is formed.

2.2 Paleoarhey - The next era, which also lasted approximately 400 million years. During this period, the kernel of the Earth is formed, the tension of the magnetic field increases. The day on the planet lasted only 15 hours. But the oxygen content increases in the atmosphere due to the activities of the bacteria. The remains of these first forms of Paleoarha's era of life were found in Western Australia.

2.3 Mesoarhey Also lasted about 400 million years. In the Mesoarha Era, our planet covered the shallow ocean. Sushi plots were small volcanic islands. But already during this period the formation of a lithosphere begins and the mechanism of tectonics of plates is launched. At the end of Mesoarhery, the first ice age is observed, during which snow and ice on Earth are formed on Earth. Biological species are still presented by bacteria and microbial forms of life.

2.4 Neoarhey - the final era of the Archean Eon, the duration of which is about 300 million years. Colonies of bacteria at this time forms the first stromatolites (limestone deposits). The essential event of Neoarhey is the formation of oxygen photosynthesis.

II. Proterozoa - One of the longest time segments of the history of the Earth, which is customary to divide for three eras. During the Proterezhoy, the ozone layer appears for the first time, the global ocean reaches almost modern volume. And after a long-lasting Guronian glaciation on Earth, the first multicellular forms of life appear - mushrooms and sponges. It is customary to divide for three eras, each of which contained several months.

3.1 Paleo-Proteroza - The first era of Proterozoy, which began 2.5 billion years ago. At this time, a lithosphere is fully formed. But the former forms of life due to an increase in oxygen content almost extinct. This period was called an oxygen catastrophe. By the end of the era on Earth, the first eukaryotes appear.

3.2 Meso-Proteroza Little approximately 600 million. The most important events of this era: the formation of continental masses, the formation of the supercontinent of the birthplace and the evolution of sexual reproduction.

3.3 Neo-Proteroza. During this era, the birthplace disintegrates about 8 parts, the world's super pool ceases its existence, and on the outcome of the era, the Earth almost to the equator is covered with ice. In the neoproterozoic era, living organisms first begin to acquire a solid shell, which will continue to serve as the basis of the skeleton.

III. Paleozoic - The first era of Puerrozoic Eon, which began approximately 541 million years ago and lasted about 289 million years. This is the era of the appearance of an ancient life. The supercontinent of the Gondwana combines the southern continents, a little later, the rest of the sushi are attached to it and Pangea appears. Climatic belts are beginning to be formed, and the flora and fauna are presented mainly by marine species. Only by the end of the Paleozoa begins the development of sushi, and the first vertebrates appear.

Paleozoic era is conditionally divided by 6 periods.

1. Cambrian period lasted 56 million years. During this period, the main rocks are formed, and the mineral skeleton appears in living organisms. And the most important event of Cambria is the emergence of the first arthropods.

2. Ordovik period - The second period of Paleozoic, which lasted 42 million years. This is the era of the formation of sedimentary breeds, phosphorites and combustible shale. The organic world of Ordovic is represented by sea invertebrates and blue-green algae.

3. Silician period covers the following 24 million years. At this time, almost 60% of living organisms that existed before are extinct. But the first crystal and bone fish appear in the history of the planet. On land, the silicon marks the emergence of vascular plants. Superkontinets come closer and form Laurelasia. By the end of the period, melting of ice was marked, the sea level rose, and the climate became softer.

4. Devonian period It is distinguished by the rapid development of various forms of life and the development of new environmental niches. Devon covers a time interval of 60 million years. The first terrestrial vertebrates appear, spiders, insects. In animals sushi form lungs. Although, still, the fish prevail. The kingdom of flora of this period is represented by the suspension, horsages, plauns and the memorable.

5. Coal period often called carbon. At this time, the laure is faced with Gondwayn and a new supercontinent of Pangea appears. The new ocean - Tetis is formed. This is the time of the appearance of the first amphibians and reptiles.

6. Perm period - The last period of Paleozoic, completed 252 million years ago. It is assumed that at this time a large asteroid fell to Earth, which led to a significant change in climate and extinct almost 90% of all living organisms. Most of the sushi are covered with sands, the most extensive deserts appear, which only existed in the entire history of the earth's development.

IV. Mesoza - The second era of Puerozoic Eon, which lasted almost 186 million years. At this time, continents acquire almost modern outlines. A warm climate contributes to the rapid development of life on Earth. Giant ferns disappear, and coated plants appear on the shift. Mesoza is the era of dinosaurs and the appearance of the first mammals.

In the Mesozoic era, three periods are distinguished: TRIAS, Yura and Chalk.

1. Triassic period lasted just over 50 million years. At this time, Pangea begins to split, and the inner seas gradually minor and dry. The climate is soft, zones are not pronounced. Almost half of the plant sushi disappears, as the deserts are spread. And in the kingdom of fauna, the first warm-blooded and land reptiles appear, which raised the ancestors of dinosaurs and birds.

2. Jurassic covers the gap of 56 million years. The wet and warm climate reigned on Earth. Sushha is covered with thickets of ferns, pines, palm trees, cypresses. Dinosaurs reign on the planet, and numerous mammals were distinguished while small growth and thick wool.

3. Cretaceous period - The longest period of the Mesozoic, which lasted almost 79 million years. The split continents almost ends, the Atlantic Ocean increases significantly in the amount, ice cover are formed on the poles. An increase in the aqueous mass of oceans leads to the formation of a greenhouse effect. At the end of the chalk period there is a catastrophe, the reasons for which are still not clear. As a result, all dinosaurs and most types of reptiles and gifted plants were extinct.

V. Cenozoa - This is the era of animals and a man of reasonable, which began 66 million years ago. The continents at this time acquired their modern outline, Antarctica took the South Pole of the Earth, and the oceans continued to increase. The plants and animals survived after the catastrophe of the Cretaceous period were in a completely new world. Each continent began to form unique communities of life forms.

The Cenozoic Era is divided into three periods: Paleogen, Neogen and Quaternary.

1. Paleogenic period Approximately 23 million years ago ended. At this time, a tropical climate reigned on Earth, Europe hid under the evergreen tropical forests, only deciduous trees grew in the north of the continents. It was during the period of Paleogen that the mammals are rapid development.

2. Neugenic period covers the next 20 million years of the development of the planet. Whales and manochable appear. And, although the saber tigers and Mastodonts still roam the land, the fauna more and more becomes modern features.

3. Quaternary period Began more than 2.5 million years ago and continues until now. Two major events characterize this time segment: the ice age and the appearance of a person. The glacier era fully completed the formation of climate, flora and fauna of continents. And the emergence of man marked the beginning of civilization.

How did the earth originate?

There are several theories of our planet's emergence at once, each of which has its own supporters and their right to life. Of course, absolutely accurately determine what the theories actually describes the emergence of the Earth and there is such a theory in general, it is impossible, but in this article we will look at each of them in detail. The question of the emergence of land is still not fully studied and has no absolutely accurate answer.

Contemporary idea of \u200b\u200bthe birth of the planet Earth

To date, the most recognized the theory of the emergence of the planet Earth is the theory according to which the Earth has formed from the gas-dust-dusty-dusty system.

According to this theory, the sun appeared earlier than the planets, and the land, like other planets of the solar system, originated from the debris, gas and dust left after the formation of the Sun. Thus, it is believed that the Earth formed about 4.5 billion years ago, and the process of its formation took approximately 10 to 20 million years.

The history of the development of the theory

The first theory in 1755 put forward the German philosopher I. Kant. He believed that the sun and the planets of the solar system appeared from dust and gas, which were scattered in space. Dust and gas particles under the action of a shock wave from a large explosion randomly moved, faced each other by passing energy. Thus, the most severe and large particles were formed, which attracted each other and eventually formed the sun. After the sun has acquired a large size, smaller particles began to rotate around it, whose movement paths intersected. Thus, gaseous rings were formed, in which the light particles were attracted to heavier nuclei, creating spherical clusters, which became future planets.

There are other theories about the emergence of land, which at different times have been put forward by different scientists and even had their followers in the future.

Tidal theory of land origin

According to this theory, the sun appeared much earlier planets, and the land and other planets of the solar system were formed from substances secreted by the Sun or another large star.

The history of the development of the theory

The history of this theory began in 1776, when Mathematician J. Buffon nominated theory of the collision of the Sun with a comet. As a result of this clash, the material was released from which the planet Earth and other planets were originated.

This theory found its follower in the XX century. It was then that scientist Astrophysic I.I. Wulfson, with the help of calculations on the computer, showed that the star should not be faced with the Sun. According to his theory, any big and cold star from the new accumulation of the stars could approach the sun on a small distance and thereby cause gigantic tides both on their surface and in the sun. The amplitude of these tides is growing until the material breaks away from the Sun or the approaching star and does not take place between these star bodies in the form of a cigar-like jet. Then the cold star goes away, and the jet appeared scattered on the planet of the solar system.

How the land was born according to the "nebular theory"

The creator of the first nebular theory was French astronomer and mathematician P.-S. Laplace. He believed that there was a gas disk rotating from compression; The speed of its rotation increased until the centrifugal force at its edge began to exceed the gravitational force of attraction. After that, the disk burst, and after a while this process was repeated. Thus, the rings turned into planets, and the central mass in the sun.

This theory well explains the fact of rotation of the Earth and the Sun in the same plane and one direction, but it also has significant gaps.

According to this theory, the sun should rotate very quickly (with a period of rotation in several hours). However, in fact, the Sun rotates much slower - 1 turnover in 27 days. Another lack of theory is a mechanism for collecting particles into the planet. The theory does not respond to the question of why substances after breaking the disk were divided into rings, and did not take the form of the same disk, but smaller sizes.

On this we finish the story about the emergence of the planet Earth and recommend that you read about.

\u003e Planet Earth

Everything about planet Land For children: As appeared and formed, interesting facts, which consists of a structure in the photo and drawings, the rotation of the earth, the moon and life.

Start a story about the earth for the smallest It is possible from the fact that we live on the third planet from the sun. Parents or teachers at school should be explain the childrenthat they are very lucky. After all, the Earth is still the only well-known planet of the solar system containing the atmosphere with oxygen, liquid oceans on the surface and life.

If we consider in size, then we occupy the fifth place (less, and, but more and).

The diameter of the planet Earth is 13000 km. It has a circular shape, because gravity pulls the matter. Although it is not the perfect circle, because the rotation causes the planet to sill in the poles and expand on the equator.

Water takes approximately 71% (most of the oceans). 1/5 The atmosphere consists of oxygen, which produce plants. So far, scientists have studied the planet, spacecraft made it possible to look at her from space. Below, schoolchildren and children of all ages will be able to consider interesting facts about the land and get a full description of the third planet from the sun with a photo and pictures. But it should be recalled that the earth has a class, or rather the planetary type is a rocky body (there are also ice and gas giants that differ in characteristics).

Earth orbit characteristics - Explanation for children

To give complete explanation for children, parents Must reveal the concept of the axis. This is an imaginary line running through the center from the North to the South Pole. One turn is 23,934 hours, and on the near-free orbit - 365.26 days (earthly year).

Children It should be known that the earth's axis is inclined relative to the plane of the ecliptic (the imaginary surface of the orbit of the Earth around the Sun). Because of this, the northern and southern hemisphere sometimes turn and turn away from the sun. This leads to a change of seasons (the resulting amount of light and heat change).

Earth's orbit is not an ideal circle, and an oval ellipse (this is inherent to all planets). It approaches the Sun in early January and is moving in July (although it is less affected by heating and cooling than the slope of the earth's axis). Follow explain the children The value of finding the planet in the inhabited zone. This is a distance that allows the temperature to maintain water in a liquid state.

Orbit and Rotation of Earth - Explanation for Children

• Average remoteness from the Sun: 149 598 262 km.
• Perihelium (the closest distance to the Sun): 147,098,291 km.
• Aflia (the most remote distance from the sun): 152,098 233 km.
• Sunny day duration (one axial turnover): 23,934 hours.
• Duration of the year (one bypass around the Sun): 365.26 days.
• Equatorial tilt to orbit: 23.4393 degrees.

The formation and evolution of the Earth is an explanation for children

Explanation for children will remain incomplete if description of land will be prehistory. Researchers believe that the Earth has formed together with the Sun and other planets 4.6 billion years ago. Then reunited with a huge gas and dusty cloud - solar nebula. The power of gravity gradually destroyed it, giving more speed and the form of the disk. Most of the material pulled into the center and started forming.

Other particles came across and combined, forming larger bodies. Sunny wind has such a force that he managed to shift lighter elements (hydrogen and helium) from the most remote worlds. That is why the Earth and other planets became rocky.

In the early history of the planet, the Earth for children can seem like a lifeless piece of rock. Radioactive materials and a growing pressure of the pressure have been given enough heat to melt the inner space. Because of this, some chemicals splashed out, forming water, while others became atmospheric gases. According to the latest data, the bark and oceans could appear in 200 million after the formation of the planet.

Children We must know that the earthly story is divided into 4 Eon: Hadic, Archean, Proterozoic and Plyonozoic. The first three occupied almost 4 billion years and together are called Precambrian. Evidence of living has discovered about 3.8 billion years ago in Archey. But life did not differ in wealth to plywood.

The pilaeros period is divided into 3 epochs: Paleozoa, Mesoza and Cenozoa. The first demonstrated the emergence of many varieties of animals and plants in the seas and on land. Mesoza provided dinosaurs, but the Cenozoa is literally our era (mammals).

Most of Paleozoic fossils are invertebrate animals (corals, trilobites and clams). Father's fossils dated age of 450 million years, and amphibians - 380 million years. Huge forests, swamps and early reptiles settled the Earth 300 million years ago.

Mesoza became a period of life of dinosaurs. Although mammalian fossils also had age in 200 million years. During this period, the power captured the flowering plants (and continue to hold it today).

Cenoza started about 65 million years ago, when dinosaurs were extinct (scientists attribute this merit to cosmic effects). Mammals managed to survive, and they became the main creatures on the planet.

The composition and structure of the Earth is an explanation for children

Atmosphere

Ingredients: 78% nitrogen and 21% oxygen with small impurities of water, carbon dioxide, argon and other gases. More anywhere in the solar system you will not find the atmosphere filled with free oxygen. But it was precisely important for our lives.

The land surrounds the air, becoming thin as the remoteness is removed from the surface. At an altitude of 160 km, it is so thin that the satellites have to overcome only minor resistance. But traces of the atmosphere still find at an altitude of 600 km.

The lowest layer of the atmosphere is a troposphere. She does not stop their movement and is responsible for weather conditions. Sunlight heats the atmosphere, creating a warm air flow. It expands and cools with a decrease in pressure. Children It should understand that the cold air becomes more dense, so it drops down to warm up in the lower layers.

At an altitude of 48 km is the stratosphere. This is a fixed ozone layer created by ultraviolet light that caused the trio of oxygen atoms to form the ozone molecule. For the smallest It will be interesting to know that it is ozone that protects us from most of the dangerous ultraviolet radiation.

Carbon dioxide, water vapor and other gases delay heat and heat the ground. If it were not for this "greenhouse effect", the surface would be too cold and would not allow to develop life. Although the wrong Greenhouse could turn us into Hells a hot analogue of Venus.

Satellites in the near-earth orbit showed that the upper atmosphere is expanding during the day and decreases at night due to heating and cooling processes.

A magnetic field

The magnetic field of the Earth is created by threads emanating from the outer layer of the earth's core. Magnetic poles always move. The Magnetic North Pole accelerates up to 40 km per year. A few decades he will leave North America and reaches Siberia.

NASA believes that the magnetic field changes in other directions. Around the world, it weakened by 10%, if measured from the 19th century. Although these transformations are insignificant if you deepen in the distant past. Sometimes the field completely turned over, changing the northern and south poles in places.

When the Sun charged particles turn out to be in a magnetic field, they are divided into air molecules above the poles and create radiance - Northern and South.

Chemical composition

The most common element in the earth's crust is oxygen (47%). Next comes silicon (27%), aluminum (8%), iron (5%), calcium (4%), and 2% of potassium, sodium and magnesium.

As part of the core of the Earth mainly: nickel, iron and lighter elements (sulfur and oxygen). The mantle is made of silicate rocks rich in iron and magnesium (a combination of silicon and oxygen - silica, and the materials containing it are called silicate).

Internal structure

Schoolchildren and children of all ages should be remembered that the earth's core reaches 7100 km wide (it is a little more than half of the earth diameter and is approximately equal to the size of Mars). The most distant layers (2250 km) are liquid, but internal represents a solid body and reaches 4/5 of the moon size (2600 km in diameter).

Above the core is a mantle with a thickness of 2900 km. Children Could hear at schoolthat it is not quite tough, but it can flow very slowly. The earth bark sails on it, which causes the almost imperceptible offset of the continents. True, people are aware of it in the form of an earthquake, spewing volcanoes and forming mountain ranges.

There are two types of earthly crust. The land of continents consists mostly of the granite and other light silicate minerals. The ocean floors represent the dark and dense volcanic breed - basalt. The continental bark in thickness reaches 40 km, although it may differ depending on the specific area. Oceanic grows only to 8 km. Water fills low areas of basalt and forms the world ocean. The earth has a lot of water, so it completely fills the ocean pools. The rest of the same part reaches the edges of the continents - the continental loop.

The closer to the kernel, the heat. At the very bottom of the continental cortex, the temperature reaches 1000 ° C and increases by 1 ° C with each kilometer down. Geologists suggest that the external kernel is rolled to 3700-4300 ° C, and internal - 7000 ° C. It is even hotter than on the surface of the sun. Only huge pressure allows you to maintain its structure.

Recent exoplanet studies (for example, the mission of Kepler NASA) suggest that the planets of the Land are found throughout our galaxy. Almost a quarter of the observed solar stars can have potential inhabited lands.

Ground Moon - Explanation for Children

Children should not forget that the earth has a faithful satellite - the moon. The width reaches 3474 km (about a quarter of the earth's diameter). Our planet has only one satellite, although Venus and Mercury have them at all, and some have two or more.

The moon formed after a giant object crashed into the ground. Torn fragments and became a composite material of the moon. Scientists believe that the object was approximately the size of Mars.

It is still known that the Earth is the only planet in the universe, inhabited by life. There are several million known species from the very deep ocean bottom to the highest levels of the atmosphere. But the researchers say that not yet all detected (about 5-100 million, of which they only found about 2 million).

Scientists suspect that there are other inhabited planets. Among them are the satellite Saturn Titan or Europe of Jupiter. While the researchers still understand the evolution processes and it seems that Mars has every chance for organisms. Some think that it is from Martian meteorites that fell to the ground, and our life originated.

It is important to remind children that our planet is considered the most studied, because the study of the land is conducted from primitive tribes to today. Many interesting sciences offer the characteristics of the planet from all sides. The geography of the Earth reveals the country, geology studies the composition and movement of plates, and biology considers living organisms. So that the child is more interesting to explore land, use printed or google cards, as well as our online telescopes. Do not forget that the planet Earth is a unique system and the only world with life. Therefore, it needs not only to study comprehensively, but also to protect.

The history of the planet Earth, as well as human life, is filled with various important events and stages of development that occurred since its birth. Before the planet Earth appeared and all other celestial bodies: planets and stars in space flew dust clouds. The blue planet, as well as the remaining solar system objects, including the Sun, as scientists suggest, was formed during the seal of the interstellar dust cloud.

The land was formed somewhere 10 million years after the interstellar dust began to compact. The heat generated formed the celestial body from the molten substance. After the planet Earth appeared. The differentiation of the layers of the components of it led to the appearance of the inner nucleus from the heavy elements wrapped by mantle, the accumulation on the surface of the light elements was the cause of the formation of a proto bark. At the same time, the moon appeared, possibly due to a strong collision between the land and a huge asteroid.

Over time, the planet was cooled, there was a hardened shell - bark, and subsequently the first continents. From the moment the Planet Earth appeared, it was constantly bombed by meteorites and ice comets, as a result, enough water was accumulated on the surface, for the formation of seas and oceans. Thanks to strong volcanic activity, the atmosphere appeared in which the oxygen was practically absent. In the entire history of the planet, the continent's land was incentively floating on the molten mantle, then connecting that, disconnecting, it was repeated many times for 4.5 billion years.

Complex chemical reactions caused the appearance of organic molecules interacting with each other, more and more complex molecular structures appeared. As a result, it led to the appearance of molecules capable of self-copying. These were the first steps of life on Earth. Living organisms developed, bacteria appeared, then multicellular organisms. In the process of the vital activity of these organisms, the composition of the atmosphere has changed. Oxygen appeared, which led to the development of the protective layer of ozone.

Life has developed in numerous forms, the number of types on Earth amazes with its diversity. The change in the conditions of the medium in the history of the planet led to the emergence of new species, many of which were extinct, others were able to adapt to the new environment and created a modern biosphere.

About 6 million years ago, after billion years after the Earth appeared, the branch of the evolutionary differentiation of primates led to the emergence of people. The ability to move on the hind legs, a strong increase in the size of the brain and the development of the speech was the main factors. At first, the person learned how to extract the fire, then achieved success in the development of agriculture. This led to an improvement in life, which led to the formation of communities and after civilizations, with different cultural and religious signs. Thanks to its achievements in different areas: science, politics, writing, transport and communications, people have become a predominant view of Earth. No earth forms life forms, a person changes the environment in the process of vital activity. For the first time the history of the planet Earth, the creatures of the creatures that live on it, and it is we forced to solve global climate issues and other environments to conserve our habitat.

Earth - the third planet from the sun and the fifth size among all the planets of the solar system. It is also the largest in diameter, mass and density among the planets of the earth group.

Sometimes it is referred to as the world, a blue planet, sometimes terra (from lat. Terra). The only well-known person at the moment the body of the solar system in particular and the universe in general, populated by living organisms.

Scientific data indicate that the Earth was formed from the solar nebula about 4.54 billion years ago, and soon after that I had acquired my only natural satellite - the moon. Life appeared on Earth about 3.5 billion years ago, that is, for 1 billion after her occurrence. Since then, the biosphere of the Earth has significantly changed the atmosphere and other abiotic factors, determining the quantitative growth of aerobic organisms, as well as the formation of the ozone layer, which, together with the magnetic field of the Earth, weakens the solar radiation harmful to life, thereby maintaining the living conditions on Earth.

Radiation caused by the earthly crust itself, since its formation, it has significantly decreased due to the gradual decay of the radionuclides in it. The Earth bark is divided into several segments, or tectonic plates that move along the surface with speeds of the order of several centimeters per year. Approximately 70.8% of the surface of the planet occupies the world ocean, the rest of the surface is occupied by the continents and islands. Rivers and lakes are located on the mainland, together with the world ocean, they constitute a hydrosphere. Liquid water required for all known life forms does not exist on the surface of any of the well-known planets and planetoids of the solar system, except the Earth. The Pole of the Earth is covered with an ice shell, which includes the sea ice of the Arctic and Antarctic Ice Shield.

The internal areas of the Earth are quite active and consist of a thick, very viscous layer called mantle, which covers the liquid external core, which is the source of the magnetic field of the Earth and the inner solid core, presumably consisting of iron and nickel. The physical characteristics of the Earth and its orbital movement allowed life to continue for the past 3.5 billion years. According to various estimates, the Earth will preserve the conditions for the existence of living organisms for another 0.5 - 2.3 billion years.

The land interacts (attracted by gravitational forces) with other objects in space, including the sun and the moon. The land turns around the sun and makes around it a full turn around for about 365.26 sunny day - a Sideric year. The axis of rotation of the Earth is tilted by 23.44 ° relative to the perpendicular to its orbital plane, it causes seasonal changes on the surface of the planet with a period of one tropical year - 365.24 sunny day. The day now make up about 24 hours. The moon began his appeal in orbit around the Earth approximately 4.53 billion years ago. The gravitational impact of the Moon on Earth is the cause of ocean tides. Also, the moon stabilizes the slope of the earth's axis and gradually slows the rotation of the Earth. Some theories believe that the drops of asteroids led to significant changes in the environment and the surface of the Earth, causing, in particular, mass extinctions of various types of living beings.

The planet is home to millions of living beings, including a person. The territory of the Earth is divided into 195 independent states that interact with each other by diplomatic relations, travel, trade or hostilities. Human culture has formed a lot of ideas about the universe device - such as the concept of flat land, the geocentric system of the world and the GEAS hypothesis, according to which the Earth is a single superorganism.

History of land

The modern scientific hypothesis of the formation of the Earth and other planets of the solar system is the hypothesis of solar nebula, in which the solar system was formed from a large cloud of inter-storage dust and gas. The cloud consisted mainly of hydrogen and helium, which were formed after a large explosion and more heavy elements left by supernova explosions. Approximately 4.5 billion years ago, the cloud began to shrink, which was probably due to the impact of the shock wave from the supernova overlooking several light years. When the cloud began to shrink, its angular momentum, gravity and inertia fightened it into the protoplanetic disk perpendicular to its axis of rotation. After that, the debris in the protoplanet disk under the action of the force of attraction began to face, and, merging, formed the first planetoids.

In the accretion process of planetoids, dust, gas and debris, which remained after the formation of the solar system, began to merge into increasingly large objects, forming planets. Approximate date of earth formation - 4.54 ± 0.04 billion years ago. The whole process of formation of the planet occupied about 10-20 million years.

The moon has been formed later, approximately 4.527 ± 0.01 billion years ago, although its origin is still definitely not established. The main hypothesis states that it was formed by accretion from the substance left after the tangent collision of the Earth with the object, in size to close Mars and weighing 10% of the earth (sometimes this object is called "Tayya"). As a result of this collision, it was released about 100 million times more energy than as a result of the disintegration of dinosaurs. This was enough to evaporate the external layers of the Earth and melting both bodies. Part of the mantle was thrown into the orbit of the Earth, which predicts why the moon is deprived by metal material, and explains its unusual composition. Under the influence of its own gravity, the elevated material took the spherical shape and the moon was formed.

Procentle increased due to accretion, and was routine enough to melt metals and minerals. Iron, as well as geochemically sprinkled siderophilic elements, possessing a higher density than silicates and aluminosilicates, descended to the center of the Earth. This led to the separation of internal layers of land on the mantle and the metal core after only 10 million years after the land began to form, producing a layered structure of the Earth and forming the magnetic field of the Earth. The release of gases from the crust and volcanic activity led to the formation of the primary atmosphere. The condensation of water vapor, amplified by ice, brought by comets and asteroids, led to the formation of oceans. The earth's atmosphere then consisted of lightly atmospil elements: hydrogen and helium, but contained significantly more carbon dioxide than now, and this was a replete ocean from freezing, since the luminosity of the Sun then did not exceed 70% of the current level. Approximately 3.5 billion years ago, the magnetic field of the Earth was formed, which prevented the empty of the atmosphere by the solar wind.

The surface of the planet was constantly changing over hundreds of millions of years: the continents appeared and destroyed. They moved over the surface, sometimes gathering in the supercontinent. Approximately 750 million years ago the earliest of the famous supercontinents - the birthplace - began to split into parts. Later, these parts were united in Pannament (600-540 million years ago), then in the last of the supercontinents - Pangayu, which broke up 180 million years ago.

The emergence of life

There are a number of the hypotheses of the occurrence of life on Earth. About 3.5-3.8 billion years ago, "the last universal overall ancestor" appeared, from which all other living organisms subsequently occurred.

The development of photosynthesis allowed living organisms to use solar energy directly. This led to an oxygenation of the atmosphere, which began approximately 2500 million years ago, and in the upper layers - to the formation of the ozone layer. Symbiosis of small cells with larger led to the development of complex cells - eukaryotes. Approximately 2.1 billion years ago, multicellular organisms appeared, which continued to adapt to the surrounding conditions. Due to the absorption of destructive ultraviolet radiation, the ozone layer was able to start mastering the surface of the Earth.

In 1960, the hypothesis of the Earth-Snowball was put forward, which claims that between 750 and 580 million years ago, the land was completely covered with ice. This hypothesis explains the Cambrian explosion - a sharp increase in the diversity of multicellular living forms of about 542 million years ago.

About 1200 million years ago, the first algae appeared, and approximately 450 million years ago - the first higher plants. Invertebrate animals appeared in the Eidiac period, and vertebrates - during the Cambrian explosion about 525 million years ago.

After the Cambrian explosion there were five mass extinction. The extinction at the end of the Perm period, which is the most massive in the history of life on Earth, led to the death of more than 90% of living beings on the planet. After the Perm catastrophe, the most common ground verteons became Arhozavra, from which dinosaurs occurred at the end of the triad period. They dominated the planet during the Jurassic and Cretaceous Periods. 65 million years ago there was a chalk-Paleogenic extinction, caused, probably a drop in a meteorite; It led to the disappearance of dinosaurs and other major reptiles, but bypassed many small animals, such as mammals, which were then small insectivorous animals, as well as birds that are the evolutionary branch of dinosaurs. During the last 65 million years, a huge number of various types of mammals have developed, and several million years ago, monkey-like animals obtained the ability of straightening. This made it possible to use tools and contributed to communication that helped to extract food and stimulated the need for a big brain. The development of agriculture, and then civilization, in a short time allowed people to influence Earth as no other form of life, affect nature and the number of other species.

The last glacial period began approximately 40 million years ago, his peak falls on Pleistáz about 3 million years ago. Against the background of long and significant changes in the average temperature of the earth's surface, which can be due to the period of circulation of the solar system around the center of the Galaxy (about 200 million years), there are less than the amplitude and duration of cycles of cooling and warming, occurring every 40-100 thousand years. Having an obviously auto-oscillatory nature, possibly caused by the effect of reverse links from the reaction of the entire biosphere as a whole, seeking to ensure the stabilization of the land climate (see Gay hypothesis, nominated by James Lavlock, as well as the theory of biotic regulation proposed by V. G. Gorshkov).

The last cycle of glaciation in the northern hemisphere ended about 10 thousand years ago.

Structure of land

According to the theory of tectonic plates, the outer part of the Earth consists of two layers: lithosphere, including the earth's bark, and the hardened top of the mantle. Under the lithosphere is an asthenosphere, which makes up the outer part of the mantle. Asthenosphere behaves like overheated and extremely viscous liquid.

The lithosphere is divided into tectonic plates, and as if floating on an asthenosphere. Plates are rigid segments that move relative to each other. There are three types of their mutual movement: convergence (convergence), divergence (discrepancy) and shear movements for transform faults. On faults between the tectonic plates, earthquakes, volcanic activity, the formation, the formation of the ocean varieties can occur.

The list of largest tectonic plates with sizes is shown in the table on the right. Among the slabs of smaller sizes should be noted by the Industan, Arab, Caribbean stoves, the plate of Nask and the stove plate. The Australian stove actually merged with the Industanian between 50 and 55 million years ago. Ocean plates are moving faster; So, the coco plate moves at a speed of 75 mm per year, and the Pacific cooker - at a speed of 52-69 mm per year. The lowest speed of the Eurasian Plate is 21 mm per year.

Geographic shell

The near-surface parts of the planet (the upper part of the lithosphere, the hydrosphere, the lower layers of the atmosphere) are generally called a geographic shell and are studied by geography.

Earth relief is very diverse. About 70.8% of the surface of the planet is covered with water (including continental shelves). The underwater surface is mountainous, includes a system of mid-ocean ridges, as well as underwater volcanoes, oceanic chute, underwater canyons, oceanic plateaus and abissual plains. The remaining 29.2%, uncovered with water, include mountains, deserts, plains, platea, etc.

During the geological periods, the surface of the planet is constantly changing due to tectonic processes and erosion. The relief of tectonic plates is formed under the influence of weathering, which is a consequence of precipitation, temperature fluctuations, chemical influences. The earth's surface and glaciers, coastal erosion, the formation of coral reefs, collisions with major meteorites are changed.

When moving continental plates on planet, the oceanic bottom is immersed under their impending edges. At the same time, the substance of the mantle rising from the depths creates a divergent border on the mid-oceanic ridges. Together, these two processes lead to a constant updating of the material of the oceanic plate. The age of most of the ocean bottom is less than 100 million years. The oldest ocean bark is located in the western part of the Pacific Ocean, and its age is approximately 200 million years. For comparison, the age of the oldest fossils found on land reaches about 3 billion years.

Continental plates consist of low-density material, such as volcanic granite and andhesite. Basalt is less common - dense volcanic rock, which is the main component of the oceanic bottom. Approximately 75% of the surface of the mainland is coated with sedimentary rocks, although these breeds range about 5% of the earth's crust. Third-time prevalence on Earth rocks are metamorphic rock rocks formed as a result of changes (metamorphism) of sedimentary or igneous rocks under the action of high pressure, high temperature or both at the same time. The most common silicates on the surface of the earth are quartz, field spat, amphibole, mica, pyroxen and olivine; Carbonates - calcite (in limestone), aragonit and dolomite.

Pedosphere is the topmost layer of the lithosphere - turns on the soil. It is located on the border between the lithosphere, the atmosphere, hydrosphere. Today, the total area of \u200b\u200bcultured land is 13.31% of the sushi surface, of which only 4.71% are constantly engaged in agricultural crops. Approximately 40% of the earth sushi is used for arable land and pastures, it is approximately 1.3 · 107 km² of arable land and 3.4 · 107 km² pastures.

Hydrosphere

Hydrosphere (from Dr. Greek. YΔωρ - water and σφαῖρα - ball) - a set of all water reserves of the Earth.

The presence of liquid water on the surface of the Earth is a unique property that distinguishes our planet from other objects of the solar system. Most of the water focuses in the oceans and seas, significantly less - in river networks, lakes, swamps and underground waters. Also large water reserves are available in the atmosphere, in the form of clouds and water vapor.

Part of the water is in a solid state in the form of glaciers, snow cover and in the eternal Merzlot, the famous cryosphere.

The total mass of water in the world ocean is approximately 1.35 × 1018 tons, or about 1/4400 on the total mass of the Earth. Oceans cover area of \u200b\u200babout 3,618 · 108 km2 with an average depth of 3682 m, which allows calculating the total volume of water in them: 1.332 · 109 km3. If all this water is uniformly distributed over the surface, then it would be a layer, with a thickness of more than 2.7 km. Of all the water, which is on Earth, only 2.5% falls on fresh, the rest is salty. Most of the fresh water, about 68.7%, is currently in glaciers. Liquid water appeared on Earth, probably about four billion years ago.

The average saline of the earth's oceans is about 35 grams of salt on a kilogram of sea water (35 ‰). A significant part of this salt was released with volcanic eruptions or extracted from chilled erupted rocks formed the bottom of the ocean.

Atmosphere of land

The atmosphere is a gas shell surrounding the planet Earth; It consists of nitrogen and oxygen, with trace amounts of water vapor, carbon dioxide and other gases. Since its inception, it has changed significantly under the influence of the biosphere. The appearance of an oxygen photosynthesis 2.4-2.5 billion years ago contributed to the development of aerobic organisms, as well as the saturation of the atmosphere with oxygen and the formation of the ozone layer, which protects everything alive from harmful ultraviolet rays. The atmosphere determines the weather on the surface of the Earth, protects the planet from cosmic rays, and partly - from meteorite bombing. It also regulates the main climate-forming processes: water cycle in nature, circulation of air masses, heat transfer. The atmosphere molecules can capture thermal energy, interfering with it to go into open space, thereby increasing the temperature of the planet. This phenomenon is known as a greenhouse effect. Basic greenhouse gases are considered water vapor, carbon dioxide, methane and ozone. Without this effect of thermal insulation, the average surface temperature of the Earth would be from minus 18 to minus 23 ° C, although in reality it is equal to 14.8 ° C, and the life most likely would not exist.

The atmosphere of the Earth is divided into layers that differ in temperature, density, chemical composition, etc. The total weight of the gases constituting the earth's atmosphere is approximately 5.15 × 1018 kg. At the sea level, the atmosphere renders pressure on the surface of 1 atm (101,325 kPa). The average air density at the surface is 1.22 g / l, and it is rapidly decreasing with height growth: so, at an altitude of 10 km above sea level, it is no more than 0.41 g / l, and at an altitude of 100 km - 10-7 g / l

At the bottom of the atmosphere contains about 80% of its total mass and 99% of the total water vapor (1.3-1.5 × 1013 tons), this layer is called a troposphere. Its thickness is not sourinak and depends on the type of climate and seasonal factors: so, in the polar regions it is about 8-10 km, in a temperate belt to 10-12 km, and in tropical or equatorial reaches 16-18 km. In this layer atmosphere, the temperature is lowered by an average of 6 ° C per kilometer when moving in height. The above is the transition layer - the tropopause separating the troposphere from the stratosphere. Temperature here is within 190-220 K.

Stratosphere - a layer of atmosphere, which is located at a height of 10-12 to 55 km (depending on weather conditions and season). It accounts for no more than 20% of the entire mass of the atmosphere. For this layer, a decrease in temperature is characterized up to a height of ~ 25 km, followed by an increase on the border with a mesosphere almost to 0 ° C. This boundary is called strato-eyed and is located at an altitude of 47-52 km. The stratosphere marks the greatest concentration of ozone in an atmosphere that protects all living organisms on Earth from the harmful ultraviolet radiation of the Sun. Intensive absorption of solar radiation by the ozone layer and causes a rapid rise in temperature in this part of the atmosphere.

The mesosphere is located at an altitude of 50 to 80 km above the surface of the Earth, between the stratosphere and the thermosphere. It is separated from these layers of mesopaousis (80-90 km). This is the coldest place on Earth, the temperature here is lowered to -100 ° C. At such a temperature, the water contained in the air quickly freezes, forming silver clouds. They can be observed immediately after sunset, but the best visibility is created when it is from 4 to 16 ° below the horizon. Most of the meteorites penetrating into the earth's atmosphere burns in the mesosphere. From the surface of the earth, they are observed as falling stars. At an altitude of 100 km above sea level there is a conditional border between the earth's atmosphere and space - the pocket line.

In a thermosphere, the temperature quickly rises to 1000 K, this is due to the absorption of short-wave solar radiation in it. This is the longest layer of the atmosphere (80-1000 km). At an altitude of about 800 km, the temperature rise stops, since the air here is very cleaned and weakly absorbs solar radiation.

The ionosphere includes the last two layers. Here is the ionization of molecules under the action of solar wind and polar radiances occur.

Exosphere is an external and very sparse part of the earth's atmosphere. In this layer, the particles are able to overcome the second space speed of the Earth and disappear into outer space. This causes a slow, but a steady process called the atmosphere dissipation (scattering). Space escapes in the main particle of light gases: hydrogen and helium. Hydrogen molecules having the lowest molecular weight can easier reach the second space speed and to flow into the outer space with a faster pace than other gases. It is believed that the loss of reducing agents, for example hydrogen, was a prerequisite for the possibility of sustainable oxygen accumulation in the atmosphere. Consequently, the property of hydrogen leave the atmosphere of the Earth, perhaps affected the development of life on the planet. Currently, most of the hydrogen falling into the atmosphere is converted into water without leaving the earth, and the loss of hydrogen occurs, mainly from the destruction of methane in the upper layers of the atmosphere.

Chemical composition of the atmosphere

At the surface of the Earth, air contains up to 78.08% nitrogen (by volume), 20.95% oxygen, 0.93% of argon and about 0.03% carbon dioxide. The fraction of the remaining components accounts for no more than 0.1%: it is hydrogen, methane, carbon monoxide, sulfur and nitrogen oxides, water vapor, and inert gases. Depending on the time of year, climate and terrain, the atmosphere may include dust, particles of organic materials, ash, soot, etc. above 200 km The main component of the atmosphere becomes nitrogen. At an altitude of 600 km, helium prevails, and from 2000 km - hydrogen ("hydrogen crown").

Weather and climate

The earthly atmosphere does not have certain boundaries, it gradually becomes thinner and more rarellied, moving to outer space. Three quarters of the mass of the atmosphere are contained in the first 11 kilometers from the surface of the planet (troposphere). Solar energy heats up this surface layer, causing expansion of air and reducing its density. Then the heated air rises, and its place occupies a colder and dense air. This arises atmospheric circulation - a system of closed currents of air masses by redistributing thermal energy.

The basis of the circulation of the atmosphere is the trade winds in the equatorial belt (below 30 ° latitude) and the western winds of the moderate belt (in latitudes between 30 ° and 60 °). Sea currents are also important factors in the formation of climate, as well as thermohalin circulation, which distributes thermal energy from the equatorial regions to the polar.

Water steam, rising from the surface, forms clouds in the atmosphere. When atmospheric conditions are allowed to rise with warm wet air, this water condenses and falls on the surface in the form of rain, snow or hail. Most of the atmospheric precipitation dropped into land falls into the river, and ultimately returns to the oceans or remains in the lakes, and then evaporates again, repeating the cycle. This cycle of water in nature is a vital factor for the existence of life on land. The amount of precipitation falling over the year is different, ranging from several meters to several millimeters, depending on the geographical position of the region. Atmospheric circulation, topological features of terrain and temperature differences determine the average precipitation, which falls in each region.

The amount of solar energy that has achieved the surface of the Earth decreases with increasing latitude. In higher latitudes, sunlight falls on the surface under a sharper corner than low; And he must pass a longer path in the earth's atmosphere. As a result, the average annual air temperature (at sea level) decreases by about 0.4 ° C when moving per 1 degree on both sides of the equator. The earth is divided into climatic belts - natural zones having approximately homogeneous climate. Climate types can be classified by temperature mode, the number of winter and summer precipitation. The most common climate classification system is the classification of Köppen, in accordance with which the best criterion for determining the climate type is what plants grow on this area in natural conditions. The system includes five main climatic zones (wet tropical forests, deserts, temperate belt, continental climate and polar type), which in turn are divided into more specific subtypes.

Biosphere

The biosphere is a combination of parts of the earth's shells (liter, hydro and atmosphere), which is populated by alive organisms, is under their impact and is engaged in products of their livelihoods. The term "biosphere" was first proposed by the Austrian geologist and a paleontologist Eduard Zyus in 1875. The biosphere is a land shell populated by alive organisms and converted by them. It began to form no earlier than 3.8 billion years ago, when the first organisms began to be born on our planet. It includes the entire hydrosphere, the upper part of the lithosphere and the lower part of the atmosphere, that is, inhabit the ecosphere. The biosphere is a totality of all living organisms. More than 3,000,000 species of plants, animals, fungi and microorganisms live in it.

The biosphere consists of ecosystems, which include communities of living organisms (biocenosis), their habitat (biotop), communication systems that carry out the metabolism and energy between them. On land, they are separated mainly by geographic latitudes, height above sea level and differences in precipitation. Ground ecosystems located in the Arctic or Antarctic, at large altitudes or in extremely arid areas, relatively poor plants and animals; A variety of species reaches a peak in wet rainforest equatorial belts.

Magnetic field of land

The magnetic field of the Earth in the first approximation is a dipole whose poles are located next to the geographic poles of the planet. The field forms a magnetosphere that deflects the solar wind particles. They accumulate in radiation belts - two concentric areas in the form of a torus around the Earth. Near the magnetic poles, these particles can "fall out" into the atmosphere and lead to the appearance of polar shine. At the Equator, the magnetic field of the Earth has an induction of 3.05 · 10-5 tons and magnetic moment 7.91 · 1015 TL · M3.

According to the theory of "Magnetic Dynamo", the field is generated in the central region of the Earth, where heat creates the flow of electrical current in the liquid metallic core. This in turn leads to the emergence of the magnetic field. Convection movements in the kernel are chaotic; Magnetic poles drift and periodically change their polarity. This causes an inversion of the magnetic field of the Earth, which arise on average several times every few million years. Last inversion occurred approximately 700,000 years ago.

The magnetosphere is the area of \u200b\u200bspace around the Earth, which is formed when the flow of charged particles of the solar wind deviates from its initial trajectory under the influence of the magnetic field. On the side facing the Sun, the thickness of her head shock wave is about 17 km and it is located at a distance of about 90,000 km from the ground. On the night side of the planet, the magnetosphere is pulled out by purchasing a long cylindrical shape.

When charged high energy particles face the Earth's magnetosphere, the radiation belts (Van Allen belt) appear. Polar radiances occur when solar plasma reaches the atmosphere of the Earth in the region of magnetic poles.

Earth orbit and Rotation

Earth is required on average 23 hours 56 minutes and 4.091 seconds (star day) to make one turn around their axis. The speed of rotation of the planet from the West to the East is approximately 15 degrees per hour (1 degree in 4 minutes, 15 'per minute). This is equivalent to the angular diameter of the Sun or Moon every two minutes (the visible sizes of the sun and the moon are about the same).

The rotation of the Earth is unstable: its speed of rotation relative to the heavenly sphere is changing (in April and November, the duration of the day differs from the reference by 0.001 c), the axis of rotation is precessing (by 20.1 "per year) and fluctuates (removing the instantaneous pole from the average does not exceed 15 ' ). On a large scale - slows down. The duration of one turnover of land increased over the past 2000 years on average by 0.0023 seconds in century (according to observations over the past 250 years this increase is less - about 0.0014 seconds in 100 years). Due to tidal acceleration, on average, every next day turns out to be longer than the previous one on ~ 29 nanoseconds

The period of rotation of the land relative to fixed stars, in the international service of the Earth's rotation (IERS), is 86164,098903691 seconds by UT1 or 23 hours. 56 min. 4.098903691 p.

The Earth moves around the Sun along the elliptical orbit at a distance of about 150 million km at an average speed of 29.765 km / s. Speed \u200b\u200branges from 30.27 km / s (perigelia) to 29.27 km / s (in Aflia). Moving in orbit, the Earth makes a complete turn for 365,2564 average sunny days (one star year). From the Earth, the movement of the Sun relative to the stars is about 1 ° per day in the eastern direction. The speed of the Earth's orbit movement is inconsistent: in July (during the passage of Afhelia) it is minimal and is about 60 corner minutes per day, and when the perichelium passes in January, about 62 minutes per day. The sun and the entire solar system draws around the center of the Milky Way Galaxy in almost a circular orbit at a speed of about 220 km / c. In turn, the solar system in the Milky Way is moving at a speed of approximately 20 km / s towards the point (APEX) located on the border of the constellation Lyra and Hercules, accelerating as the universe expands.

The moon is drawn together with the earth around the common center of the masses every 27.32 days relative to the stars. The time interval between the two identical phases of the moon (synodic month) is 29,53059 days. If you look at the North Pole of the world, the moon moves around the earth counterclockwise. In the same side, the appeal of all the planets around the Sun, and the rotation of the sun, the earth and the moon around their axis. The axis of rotation of the Earth is deflected from perpendicular to the plane of its orbit by 23.5 degrees (direction and angle of inclination of the axis of the Earth axis due to the precession, and the visible elevation of the Sun depends on the time of year); The orbit of the moon is inclined by 5 degrees relative to the orbit of the Earth (there would be one solar and one lunar eclipse without this deviation in each month).

Because of the tilt axis of the Earth, the height of the sun over the horizon changes over a year. For an observer in the northern latitudes in the summer, when an emergency pole is tilted to the Sun, the daylight lasts longer and the sun in the sky is above. This leads to higher average air temperatures. When the North Pole deviates to the opposite side of the sun, everything becomes the opposite and the climate is being done colder. The northern polar circle at this time is the polar night, which lasts almost two days on the latitude of the northern polar circle (the sun does not go on the day of the winter solstice), reaching in the North Pole of the six months.

These climate change (caused by the inclination of the earth's axis) lead to the change of the seasons. Four seasons are determined by solstice - the moments when the earth's axis is maximally tilted towards the Sun or from the Sun, and equinox. Winter solstice occurs around December 21, summer - approximately June 21, a spring equinox - approximately March 20, and autumn - September 23. When the North Pole is tilted to the Sun, South, respectively, is tilted from it. Thus, when in the northern hemisphere, the summer, in South - Winter, and on the contrary (although months are called the same, that is, for example, February in the northern hemisphere - the last (and the coldest) month of winter, and in South - the last (and the most warm ) Summer month).

The angle of inclination of the earth's axis is relatively constant for a long time. However, it undergoes minor shifts (known as nation) with a periodicity of 18.6 years. There are also long-period oscillations (about 41,000 years), known as Milankovich cycles. The orientation of the land axis over time also changes, the duration of the precession period is 25,000 years; This precession is the reason for the difference in the star and the tropical year. Both of these movements are caused by changing attraction, acting on the part of the Sun and the Moon on the equatorial convexity of the Earth. The Poles of the Earth move relative to its surface for several meters. Such a pole movement has a variety of cyclic components, which together are called a quasi-periodic movement. In addition to the one-year components of this movement, there is a 14-month cycle, called the chandler movement of the Earth's poles. The speed of rotation of the Earth is also not constant, which is reflected in the change in the duration of the day.

Currently, the Earth passes the perigelium around January 3, and the aphelies - approximately July 4th. The amount of solar energy reaching the Earth in the perihelion is 6.9% more than in Aflia, since the distance from the ground to the Sun in Aplia has more than 3.4%. This is due to the law of reverse squares. Since the southern hemisphere is tilted in the direction of the Sun at about the same time when the Earth is closest to the Sun, then during the year it gets a little more solar energy than the North. However, this effect is much less significant than the change in the total energy due to the slope of the earth's axis, and, in addition, most of the excess energy is absorbed by a large amount of water of the southern hemisphere.

For the Earth, the radius of the Hill sphere (the sphere of influence of earthly gravity) is approximately 1.5 million km. This is the maximum distance on which the effect of earth gravity is greater than the effect of gravitations of other planets and the sun.

Observation

For the first time, the land was photographed from Space in 1959 by the Explorer-6 apparatus. In 1961, Yuri Gagarin became the first person to see the Earth from Space. The crew of Apollo-8 in 1968 was the first to watch the sunrise of the Earth from the lunar orbit. In 1972, Apollo-17 crew made the famous Earth's shot - "The Blue Marble".

From the open space and from the "external" planets (located behind the Earth), it is possible to observe the passage of land through phases like lunar, as well as the Earth Observer can see the Phases of Venus (Open Galileo Galileem).

Moon

The moon is a relatively large planet satellite with a diameter of a quarter of the earth. This is the biggest, in relation to the size of your planet, satellite of the solar system. By the name of the earth's moon, the natural satellites of other planets are also called "lunas".

The gravitational attraction between the earth and the moon is the cause of earthly tides and tides. A similar effect on the moon is manifested in the fact that it is constantly drawn to the ground with the same side (the period of turnover of the moon around its axis is equal to the period of its turnover around the Earth; see also tidal acceleration of the moon). This is called tidal synchronization. During the appeal of the moon around the Earth, the Sun illuminates various sections of the satellite surface, which manifests itself in the phenomenon of lunar phases: the dark part of the surface is separated from the light terminator.

Due to the tidal synchronization of the moon, it is removed from the ground by about 38 mm per year. Through millions of years, this tiny change, as well as an increase in the Earth Day by 23 μs per year, will lead to significant changes. So, for example, in Devon (about 410 million years ago), it was 400 days, and the day lasted 21.8 hours.

The moon can significantly affect the development of life by climate change on the planet. Paleontological finds and computer models show that the slope of the earth's axis is stabilized by the tidal synchronization of the Earth with the Moon. If the axis of rotation of the Earth approached the plane of the ecliptic, then as a result, the climate on the planet would become extremely severe. One of the poles would be directed directly in the sun, and the other - in the opposite direction, and as the Earth appeals around the Sun, they would change in places. Poles would be directed right in the sun in summer and winter. Planetologists who studied such a situation argue that, in this case, all major animals and higher plants would die on Earth.

Visible from the Earth the corner size of the moon is very close to the visible size of the sun. The angular sizes (and body angle) of these two celestial bodies are similar, because even though the diameter of the sun and more lunar 400 times, it is 400 times further from the ground. With this circumstance and the presence of a significant eccentricity of the orbits of the moon, both complete and annular eclipses may be observed on Earth.

The most common hypothesis of the origin of the moon, a hypothesis of a giant clash, argues that the moon formed as a result of the collision of the protofable of the thee (about about Mars) with Proto-Earth. This, among other things, explains the reasons for the similarities and differences in the composition of the lunar soil and the earth.

Currently, the Earth has no other natural satellites, except for the moon, but there are at least two natural coal satellites - this is asteroids 3753 cruisers, 2002 AA29 and many artificial.

Asteroids bringing closer to earth

The fall in the land of large (diameter of several thousand km) asteroids is the danger of its destruction, but all similar bodies observed in the modern era for this purpose are too small and their drop is dangerous only for the biosphere. According to common hypotheses, such falls could cause several mass extinction. Asteroids with perihelial distances, smaller or equal to 1.3 astronomical units, which may be closer to the earth, less or equal to 0.05 A in the foreseeable future. e., are considered potentially dangerous objects. In total, about 6,200 facilities are registered, which take up to 1.3 astronomical units from the ground. The danger of their fall on the planet is regarded as negligible. According to modern estimates, clashes with similar bodies (according to the most pessimistic forecasts) are hardly happening more often than once a hundred thousand years.

Geographical information

Area

• Surface: 510,072 million km²
• Susha: 148.94 million km² (29.1%)
• Water: 361.132 million km² (70.9%)

Coastline length: 356,000 km

Using sushi

Data for 2011

• pushnya - 10.43%
• perennial plantings - 1.15%
• other - 88.42%

Watering lands: 3 096 621.45 km² (for 2011)

Socio-economic geography

On October 31, 2011, the population of the Earth reached 7 billion people. According to the UN estimates, the population of the Earth will reach 7.3 billion in 2013 and 9.2 billion in 2050. It is expected that the bulk of population growth will have to develop countries. The average population density is about 40 people / km2, in different parts of the Earth differs greatly, and the highest it is in Asia. According to forecasts, by 2030, the level of urbanization of the population will reach 60%, while now it is 49% on average worldwide.

Role in culture

The Russian word "Earth" dates back to Praslav. * Zemja with the same meaning that, in turn, continues Pra-I.E. * Dheĝhōm "Earth".

In English Earth - Earth. This word continues to the ancient English Eorthh and the Middle-Galia Erthe. As the name of the planet Earth was first used for about 1400. This is the only name of the planet that was not taken from Greco-Roman mythology.

Standard Astronomical Sign of Earth - Cross, Final Circle. This symbol was used in various cultures for different purposes. Another version of the symbol is a cross on the top of the circle (♁), a stylized power; Used as an early astronomical symbol of the planet Earth.

In many cultures, the Earth is deified. It is associated with the goddess, the goddess-mother, is called the mother Earth, often depicted as a goddess of fertility.

At Aztec, the land was called the tunnzin - "Our Mother". The Chinese are the goddess of Hou-Tu (后土), similar to the Greek goddess of the Earth - Gay. In the Scandinavian mythology, the goddess of Earth Erod was the mother of Torah and the daughter of Annara. In ancient Egyptian mythology, unlike many other cultures, the Earth rehearse with a man - God GEB, and the sky with a woman - the goddess of the Nut.

In many religions, there are myths about the occurrence of peace, telling about the creation of the Earth with one or more deities.

In a plurality of antique crops, the Earth was considered flat, so, in the culture of Mesopotamia, the world appeared in the form of a flat disk floating over the ocean surface. The assumptions about the spherical form of the Earth were made by the ancient Greek philosophers; Such a point of view was adhered to Pythagores. In the Middle Ages, most Europeans believed that the Earth is shaped the shape of a ball, which was witnessed by such a thinker as Thomas Akvinsky. Before the appearance of space flights, judgments about the ferrous form of the Earth were based on the observation of secondary signs and on the similar form of other planets.

Technical progress of the second half of the 20th century has changed the overall perception of the Earth. Before the start of space flights, the Earth often depicted as a green world. Frank Frank Paul, perhaps the first portrayed a cloudless blue planet (with a clearly dedicated land) on the turnover of the July issue of Amazing Stories magazine in 1940.

In 1972, the crew of Apollo-17 was made by the famous photo of the Earth, called "Blue Marble" (Blue Marble). Earth snapshot made in 1990 by Voyager-1 with a huge distance from her distance, prompted Karl Sagan to compare the planet with a pale blue dot (Pale Dot). Also, the land was compared with a large cosmic ship with a system of life support that needs to be maintained. The Earth's biosphere was sometimes described as one big body.

Ecology

In the past two centuries, a growing environmental protection is concerned about the growing influence of human activity to the nature of the Earth. The key tasks of this socio-political movement are the protection of natural resources, the elimination of pollution. Nature defenders advocate environmentally rational use of planet resources and environmental management. This, in their opinion, can be achieved by making changes to state policies and a change in the individual relations of each person. This is especially true for the large-scale use of non-renewable resources. The need to account for the impact of production on the environment imposes additional costs, which leads to the emergence of conflict between the commercial interests and ideas of environmental movements.

Future land

The future of the planet is closely connected with the future sun. As a result of accumulation in the core of the Sun "spent" helium, the luminosity of the star will begin slowly grow. It will increase by 10% over the next 1.1 billion years, and as a result of this, the inhabited zone of the solar system will shift outside the modern earth orbit. According to some climatic models, an increase in the amount of solar radiation falling on the surface of the Earth will lead to disastrous consequences, including the possibility of full evaporation of all oceans.

Increasing the surface temperature of the Earth will speed up the inorganic circulation of CO2 by reducing its concentration to death for levels of level (10 ppm for C4-photosynthesis) for 500-900 million years. The disappearance of vegetation will lead to a decrease in the oxygen content in the atmosphere and life on Earth will be impossible for several million years. Even after a billion years, water from the surface of the planet will disappear completely, and the average surface temperatures are reached 70 ° C. Most of the land will become unsuitable for the existence of life, and it must first remain in the ocean. But even if the sun was forever and invariably, then the continued inner cooling of the Earth could lead to the loss of most of the atmosphere and oceans (due to the decrease in volcanic activity). By that time, extremophils will remain the only alive creatures on Earth, organisms capable of withstanding high temperature and lack of water.

After $ 3.5 billion years of summer, the luminosity of the Sun will increase by 40% compared with the current level. The conditions on the surface of the Earth will be similar to the surface conditions of modern Venus: the oceans will completely evaporate and disappear into space, the surface will become a fruitless redden desert. This catastrophe will make it impossible to exist any forms of life on Earth. After 7.05 billion years, hydrogen reserves will end in the sunny core. This will lead to the fact that the sun will come down from the main sequence and will turn into the stage of the Red Giant. The model shows that it will increase in a radius to a value of approximately 77.5% of the current radius of the Earth orbit (0.775 a. E.), And its luminosity increases at 2350-2700 times. However, by that time the Earth's orbit may increase to 1.4 a. e., since the attraction of the Sun will weaken due to the fact that it will lose 28-33% of its mass due to the strengthening of the solar wind. However, 2008 studies show that the Earth is possible will still be absorbed by the Sun due to tidal interactions with its outer shell.

By that time the surface of the earth will be in the molten state, since the temperature on the ground is reached 1370 ° C. The atmosphere of the Earth is likely to be carried out into the outer space with the strongest solar wind, emitted by a red giant. After 10 million years since the sun, the sun will enter the phase of the red giant, the temperature in the solar core will reach 100 million k, the helium flash will occur, and the thermonuclear carbon synthesis and oxygen reaction will begin, the sun will decrease within a radius to 9.5 modern. The Helium Burning Phase stage will last 100-110 million years, after which the rapid expansion of the external shells of the star will repeat, and it will again become a red giant. Going to the asymptotic branch of the giants, the sun will increase in diameter of 213 times. After 20 million years, the period of unstable ripples of the star surface will begin. This phase of the existence of the Sun will be accompanied by powerful outbreaks, at times its luminosity will exceed the modern level 5000 times. This will occur from the fact that previously affected helium residues will be taken to thermonuclear reaction.

After about 75,000 years (according to other sources - 400,000) the sun will reset the shell, and ultimately only its small central kernel will remain from the red giant - white dwarf, small, hot, but very dense object, with a mass of about 54.1% From the initial solar. If the earth will be able to avoid the absorption by external shells of the Sun during the phase of the Red Giant, it will exist many more billions (and even trillions) years, until the Universe has been to exist, but the conditions for the re-emergence of life (at least in its current The form) on earth will not. With the entry of the sun in the phase of white dwarf, the surface of the earth will gradually cool and plunge into darkness. If you present the sizes of the sun from the surface of the future of the future, it will not look like a disk, but as a shining point with angular sizes about 0 ° 0'9. "

A black hole with a mass equal to the earth will have a Schwarzschild radius of 8 mm.

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