Man has long tried to study the world that surrounds him. How did the Earth originate? This question has worried people for more than one millennium. Many legends and predictions of various peoples of the world have survived to this day. They are united by the fact that the origin of our Earth is connected with the action of mythical heroes and gods. Only in the 18th century did scientific hypotheses about the origin of the sun and planets begin to appear.
Georges Buffon's hypothesis
French scientist Georges Buffon suggested that our Earth was formed as a result of a catastrophe. Once upon a time, a huge comet crashed into the Sun, causing numerous splashes to scatter. Subsequently, these splashes began to cool, and planets, including the Earth, were formed from the largest ones.
Rice. 1
Rice. 2. Hypothesis of the origin of the Solar system
Georges Buffon was born into the family of a wealthy landowner and was the eldest of his 5 children. Three of his brothers achieved high positions in the church hierarchy. Georges was sent to college at the age of 10, but he studied reluctantly. And I was only interested in mathematics. During this period, Buffon translated Newton's works. He was later appointed intendant of the royal garden, a post he held for 50 years until his death.
Emmanuel Kant's hypothesis
A German scientist had a different opinion Immanuel Kant. He believed that the Sun and all the planets were formed from a cold dust cloud. This cloud rotated, gradually the dust particles became denser and united - this is how the Sun and other planets were formed.
Rice. 3
Pierre Laplace's conjecture
Pierre Laplace- a French scientist and astronomer - proposed his hypothesis about the appearance of the solar system. He believed that the sun and planets were formed from a giant hot gas cloud. It gradually cooled, contracted and gave rise to the Sun and planets.
Rice. 4
Rice. 5. Hypothesis of the origin of the solar system
Pierre Simon Laplace was born on March 23, 1749 into a peasant family in Beaumont-en-Auge, in the Norman department of Calvados. He studied at the Benedictine school, from which he emerged, however, as a convinced atheist. Wealthy neighbors helped the talented boy enter the University of Caen (Normandy). Laplace proposed the first mathematically substantiated cosmogonic hypothesis for the formation of all bodies in the Solar System, called after him: the Laplace hypothesis. He was also the first to suggest that some nebulae observed in the sky are actually galaxies similar to our Milky Way.
James Jeans hypothesis
Another scientist adhered to a different hypothesis, his name is James Jeans. At the beginning of this century, he suggested that a massive star once flew near the Sun and, with its gravity, tore out part of the solar matter. This substance gave rise to all planets solar system.
Rice. 6
Rice. 7. Hypothesis of the origin of the solar system
Otto Schmidt's hypothesis
Our compatriot - Otto Yulievich Schmidt in 1944 he put forward his hypothesis about the origin of the Sun and planets. He believed that billions of years ago a giant gas and dust cloud revolved around the Sun, this cloud was cold. Over time, the cloud flattened and clumps formed. These clumps began to rotate in orbits, and planets gradually formed from them.
Rice. 8
Rice. 9. Hypothesis of the origin of the solar system
Otto Schmidt was born on September 18, 1891. As a child, he worked in a writing instruments shop. Money for the gifted boy’s education in the gymnasium was found from his Latvian grandfather Fricis Ergle. He graduated from high school in Kyiv with a gold medal (1909). He graduated from the physics and mathematics department of Kyiv University, where he studied in 1909-1913. There, under the guidance of Professor D. A. Grave, he began his research in group theory.
One of the founders and Chief Editor Big Soviet encyclopedia(1924-1942). Founder and head Department of Higher Algebra (1929-1949) of the Faculty of Physics and Mathematics / Mechanics and Mathematics of Moscow State University. In 1930-1934 he led the famous Arctic expeditions on the icebreaking ships Sedov, Sibiryakov and Chelyuskin. In 1930-1932 Director of the All-Union Arctic Institute, in 1932-1938. Head of the Main Directorate of the Northern Sea Route (GUSMP). From February 28, 1939 to March 24, 1942, he was vice-president of the USSR Academy of Sciences.
As you noticed, the hypotheses of Kant, Laplace and Schmidt are in many ways similar, and they formed the basis modern theory about the origin of the solar system and the Earth as well.
Modern hypothesis
Modern scientists suggest that the Solar system, that is, the Sun and the planets, arose simultaneously from a giant cold gas-dust cloud. This cloud of interstellar gas and dust was spinning. Gradually, clots began to form in it. The central, largest clump gave rise to a star - the Sun. Nuclear processes began to occur inside the Sun, and because of this it warmed up. The remaining clumps gave rise to planets.
Rice. 10. First stage
Rice. 11. Second stage
Rice. 12. Third stage
Rice. 13. Fourth stage
As you can see, scientists’ ideas about the emergence of our solar system and the Earth developed gradually. Today, there are still many controversial, unclear issues that modern science has to solve.
1. Melchakov L.F., Skatnik M.N. Natural history: textbook. for 3.5 grades avg. school – 8th ed. – M.: Education, 1992. – 240 p.: ill.
2. Bakhchieva O.A., Klyuchnikova N.M., Pyatunina S.K. and others. Natural history 5. – M.: Educational literature.
3. Eskov K.Yu. and others. Natural history 5 / Ed. Vakhrusheva A.A. – M.: Balass.
1. The structure and life of the Universe ().
The question of how the Earth came into being has occupied the minds of people for more than one millennium. The answer to it has always depended on the level of knowledge of people. Initially, there were naive legends about the creation of the world by some divine force. Then the Earth, in the works of scientists, acquired the shape of a ball, which was the center of the Universe. Then, in the 16th century, the doctrine of N. appeared, which placed the Earth in a number of planets revolving around the Sun. This was the first step in a truly scientific solution to the question of the origin of the Earth. Currently, there are several hypotheses, each of which in its own way describes the periods of formation of the Universe and the position of the Earth in.
Kant-Laplace hypothesis
This was the first serious attempt to create a picture of the origin of the solar system with scientific point vision. It is associated with the names of the French mathematician Pierre Laplace and the German philosopher Immanuel Kant, who worked at the end of the 18th century. They believed that the progenitor of the solar system was a hot gas-dust nebula, slowly rotating around a dense core at the center. Under the influence of the forces of mutual attraction, the nebula began to flatten and turn into a huge disk. Its density was not uniform, so separation into separate gas rings occurred in the disk. Subsequently, each ring began to thicken and turn into a single gas clump rotating around its axis. Subsequently, the clumps cooled and turned into planets, and the rings around them into satellites.
The main part of the nebula remained in the center, still did not cool down and became the Sun. Already in the 19th century, the insufficiency of this hypothesis was revealed, since it could not always explain new data in science, but its value is still great.
The Soviet geophysicist O.Yu. Schmidt imagined the development of the Solar system somewhat differently, working in the first half of the 20th century. According to his hypothesis, the Sun, traveling through the Galaxy, passed through a cloud of gas and dust and carried part of it along with it. Subsequently, the solid particles of the cloud coalesced and turned into planets, which were initially cold. The heating of these planets occurred later as a result of compression, as well as the influx of solar energy. The heating of the Earth was accompanied by massive outpourings of lava onto the surface as a result of activity. Thanks to this outpouring, the first covers of the Earth were formed.
They stood out from the lavas. They formed a primary one, which did not yet contain oxygen. More than half the volume of the primary atmosphere consisted of water vapor, and its temperature exceeded 100°C. With further gradual cooling of the atmosphere, it occurred, which led to rainfall and the formation of the primary ocean. This happened about 4.5-5 billion years ago. Later, the formation of land began, which consists of thickened, relatively light parts rising above ocean level.
J. Buffon's hypothesis
Not everyone agreed with the evolutionary scenario for the origin of planets around the Sun. Back in the 18th century, the French naturalist Georges Buffon made an assumption, supported and developed by the American physicists Chamberlain and Multon. The essence of these assumptions is this: once upon a time another star flashed in the vicinity of the Sun. Its attraction caused a huge surface on the Sun, stretching in space for hundreds of millions of kilometers. Having broken away, this wave began to swirl around the Sun and disintegrate into clumps, each of which formed its own planet.
F. Hoyle's hypothesis (XX century)
The English astrophysicist Fred Hoyle proposed his own hypothesis. According to it, the Sun had a twin star that exploded. Most of the fragments were carried into outer space, a smaller part remained in the orbit of the Sun and formed planets.
All hypotheses interpret differently the origin of the Solar system and the family ties between the Earth and the Sun, but they are united in the fact that all the planets originated from a single clump of matter, and then the fate of each of them was decided in its own way. The Earth had to travel 5 billion years and experience a series of fantastic transformations before we saw it in its modern form. However, it should be noted that there is not yet a hypothesis that does not have serious shortcomings and answers all questions about the origin of the Earth and other planets of the solar system. But it can be considered established that the Sun and the planets were formed simultaneously (or almost simultaneously) from a single material medium, from a single gas-dust cloud.
There are about 100 billion stars in one galaxy, and in total there are 100 billion galaxies in our Universe. If you wanted to travel from Earth to the very edge of the Universe, it would take you more than 15 billion years, provided that you move at the speed of light - 300,000 km per second. But where did cosmic matter come from? How did the Universe originate? The history of the Earth goes back about 4.6 billion years. During this time, many millions of species of plants and animals arose and died out; the highest mountain ranges grew and turned to dust; Huge continents either split into pieces and scattered in different directions, or collided with each other, forming new gigantic land masses. How do we know all this? The fact is that, despite all the disasters and cataclysms with which the history of our planet is so rich, surprisingly much of its turbulent past is imprinted in the rocks that exist today, in the fossils that are found in them, as well as in the organisms of living beings living on Earth today. Of course, this chronicle is incomplete. We only come across fragments of it, gaping voids between them, entire chapters that are extremely important for understanding what really happened are dropped from the narrative. And yet, even in such a truncated form, the history of our Earth is not inferior in fascination to any detective novel.
Astronomers believe that our world arose as a result Big Bang. Exploding, the giant fireball scattered matter and energy throughout space, which subsequently condensed to form billions of stars, which in turn merged into numerous galaxies.
The Big Bang Theory.
The theory followed by most modern scientists states that the Universe was formed as a result of the so-called Big Bang. An incredibly hot fireball, whose temperature reached billions of degrees, at some point exploded and scattered streams of energy and matter particles in all directions, giving them colossal acceleration.
Any substance consists of tiny particles - atoms. Atoms are the smallest material particles that can take part in chemical reactions. However, they, in turn, consist of even smaller, elementary particles. There are many varieties of atoms in the world, which are called chemical elements. Each chemical element contains atoms of a certain size and weight and is different from other chemical elements. Therefore, during chemical reactions, each chemical element behaves only in its own way. Everything in the Universe, from the largest galaxies to the smallest living organisms, consists of chemical elements.
After the Big Bang.
Because the fireball that blew apart in the Big Bang was so hot, the tiny particles of matter were initially too energetic to combine with each other to form atoms. However, after about a million years, the temperature of the Universe dropped to 4000 "C, and from elementary particles various atoms began to form. The easiest ones arose first chemical elements- helium and hydrogen. Gradually, the Universe cooled more and more and heavier elements were formed. The process of formation of new atoms and elements continues to this day in the depths of stars such as, for example, our Sun. Their temperature is unusually high.
The universe was cooling down. The newly formed atoms collected into giant clouds of dust and gas. Dust particles collided with each other and merged into a single whole. Gravitational forces pulled small objects towards larger ones. As a result, galaxies, stars, and planets formed in the Universe over time.
The Earth has a molten core rich in iron and nickel. The Earth's crust consists of lighter elements and appears to float on the surface of partially molten rocks that form the Earth's mantle.
Expanding Universe.
The Big Bang turned out to be so powerful that all the matter of the Universe scattered across outer space at great speed. Moreover, the Universe continues to expand to this day. We can say this with confidence because distant galaxies are still moving away from us, and the distances between them are constantly increasing. This means that galaxies were once located much closer to each other than they are today.
No one knows exactly how the solar system was formed. The leading theory is that the Sun and planets formed from a swirling cloud of cosmic gas and dust. The denser parts of this cloud, with the help of gravitational forces, attracted more and more matter from the outside. As a result, the Sun and all its planets arose from it.
Microwaves from the past.
Based on the assumption that the Universe was formed as a result of a “hot” Big Bang, that is, it arose from a giant fireball, scientists tried to calculate to what extent it should have cooled by now. They concluded that the temperature of intergalactic space should be about -270°C. Scientists also determine the temperature of the Universe by the intensity of microwave (thermal) radiation coming from the depths of space. The measurements carried out confirmed that it is indeed approximately -270 "C.
How old is the universe?
To find out the distance to a particular galaxy, astronomers determine its size, brightness and color of the light it emits. If the Big Bang theory is correct, then it means that all existing galaxies were originally squeezed into one super-dense and hot fireball. You just need to divide the distance from one galaxy to another by the speed at which they are moving away from each other to establish how long ago they formed a single whole. This will be the age of the Universe. Of course, this method does not allow one to obtain accurate data, but it still gives reason to believe that the age of the Universe is from 12 to 20 billion years.
A lava flow flows from the crater of the Kilauea volcano, located on the island of Hawaii. When lava reaches the Earth's surface, it hardens, forming new rocks.
Formation of the Solar System.
Galaxies probably formed about 1 to 2 billion years after the Big Bang, and the solar system arose about 8 billion years later. After all, matter was not distributed evenly throughout space. Dense areas, thanks to gravitational forces, attracted more and more dust and gas. The size of these areas increased rapidly. They turned into giant swirling clouds of dust and gas - the so-called nebulae.
One such nebula - namely the solar nebula - condensed and formed our Sun. From other parts of the cloud, clumps of matter emerged that became planets, including the Earth. They were held in their solar orbits by the powerful gravitational field of the Sun. As gravitational forces pulled particles of solar matter closer and closer together, the Sun became smaller and denser. At the same time, monstrous pressure arose in the solar core. It transformed into a colossal thermal energy, and this, in turn, accelerated the progress of thermonuclear reactions inside the Sun. As a result, new atoms were formed and even more heat was released.
The emergence of living conditions.
Approximately the same processes, although on a much smaller scale, occurred on Earth. The earth's core was rapidly shrinking. Due to nuclear reactions and the decay of radioactive elements, so much heat was released in the bowels of the Earth that the rocks that formed it melted. Lighter substances rich in silicon, a glass-like mineral, separated from denser iron and nickel in the earth's core to form the first crust. After about a billion years, when the Earth cooled significantly, the Earth's crust hardened into a tough outer shell of our planet, consisting of solid rocks.
As the Earth cooled, it ejected many different gases from its core. This usually happened during volcanic eruptions. Light gases, such as hydrogen or helium, mostly escaped into outer space. However, the Earth's gravity was strong enough to keep heavier gases near its surface. They formed the basis earth's atmosphere. Some of the water vapor from the atmosphere condensed, and oceans appeared on Earth. Now our planet was completely ready to become the cradle of life.
The birth and death of rocks.
The Earth's landmass is formed by solid rocks, often covered with a layer of soil and vegetation. But where do these rocks come from? New rocks are formed from material born deep within the Earth. In the lower layers of the earth's crust, the temperature is much higher than on the surface, and the rocks that make them up are under enormous pressure. Under the influence of heat and pressure, rocks bend and soften, or even completely melt. As soon as it forms in the earth's crust weakness, molten rocks - called magma - erupt to the surface of the Earth. Magma flows out of volcanic vents in the form of lava and spreads over a large area. When lava hardens, it turns into solid rock.
Explosions and fiery fountains.
In some cases, the birth of rocks is accompanied by grandiose cataclysms, in others it occurs quietly and unnoticed. There are many types of magma, and from them are formed Various types rocks. For example, basaltic magma is very fluid, easily comes to the surface, spreads in wide streams and quickly hardens. Sometimes it bursts out of the crater of a volcano as a bright “fiery fountain” - this happens when the earth’s crust cannot withstand its pressure.
Other types of magma are much thicker: their density, or consistency, is more like black molasses. The gases contained in such magma have great difficulty making their way to the surface through its dense mass. Remember how easily air bubbles escape from boiling water and how much slower this happens when you heat something thicker, such as jelly. As denser magma rises closer to the surface, the pressure on it decreases. Gases dissolved in it tend to expand, but cannot. When the magma finally breaks out, the gases expand so rapidly that a huge explosion occurs. Lava, rock debris and ash fly out in all directions like shells fired from a cannon. A similar eruption occurred in 1902 on the island of Martinique in the Caribbean Sea. The catastrophic eruption of the Moptap-Pelé volcano completely destroyed the port of Sept-Pierre. About 30,000 people died.
Crystal formation.
Rocks that form from cooling lava are called volcanic, or igneous, rocks. As the lava cools, the minerals contained in the molten rock gradually turn into solid crystals. If lava cools quickly, the crystals do not have time to grow and remain very small. A similar thing happens during the formation of basalt. Sometimes lava cools so quickly that it produces a smooth, glassy rock containing no crystals at all, such as obsidian (volcanic glass). This typically happens during an underwater eruption or when small particles of lava are ejected from the volcano's crater high into the cold air.
Erosion and weathering of rocks in the Cedar Breaks Canyons, Utah, USA. These canyons were formed as a result of the erosive action of the river, which laid its channel through layers of sedimentary rocks, “squeezed out” upward by movements of the earth’s crust. The exposed mountain slopes gradually eroded, and rock fragments formed rocky screes on them. In the midst of these screes stick out protrusions of still solid rocks, which form the edges of the canyons.
Evidence of the past.
The size of the crystals contained in volcanic rocks allows us to judge how quickly the lava cooled and at what distance from the surface of the Earth it lay. Here is a piece of granite, as it looks in polarized light under a microscope. Different crystals have different colors in this image.
Gneiss is a metamorphic rock formed from sedimentary rock under the influence of heat and pressure. The pattern of multi-colored stripes that you see on this piece of gneiss allows you to determine the direction in which the earth's crust, moving, pressed on the rock layers. This is how we get an idea of the events that took place 3.5 billion years ago.
By folds and faults (breaks) in rocks, we can judge in which direction colossal stresses acted in the earth's crust in long-past geological eras. These folds arose as a result of mountain-building movements of the earth's crust that began 26 million years ago. In these places, monstrous forces compressed layers of sedimentary rocks - and folds formed.
Magma does not always reach the Earth's surface. It can linger in the lower layers of the earth's crust and then cools much more slowly, forming delightful large crystals. This is how granite comes into being. The size of the crystals in some pebbles allows us to establish how this rock was formed many millions of years ago.
Hoodoos, Alberta, Canada. Rain and sandstorms destroy soft rocks faster than hard rocks, resulting in outliers (protrusions) with bizarre outlines.
Sedimentary "sandwiches".
Not all rocks are volcanic, such as granite or basalt. Many of them have many layers and look like a huge stack of sandwiches. They were once formed from other rocks destroyed by wind, rain and rivers, the fragments of which were washed into lakes or seas, and they settled at the bottom under the water column. Gradually such precipitation accumulates great amount. They pile on top of each other, forming layers hundreds and even thousands of meters thick. The water of a lake or sea presses on these deposits with colossal force. The water inside them is squeezed out, and they are pressed into a dense mass. At the same time, mineral substances, previously dissolved in the squeezed out water, seem to cement this entire mass, and as a result, a new rock is formed from it, which is called sedimentary.
Both volcanic and sedimentary rocks can be pushed upward under the influence of movements of the earth's crust, forming new mountain systems. Colossal forces are involved in the formation of mountains. Under their influence, rocks either heat up very much or are monstrously compressed. At the same time, they are transformed - transformed: one mineral can turn into another, the crystals are flattened and take on a different arrangement. As a result, in the place of one rock another appears. Rocks formed by the transformation of other rocks under the influence of the above forces are called metamorphic.
Nothing lasts forever, not even mountains.
At first glance, nothing could be stronger and more durable than a huge mountain. Alas, this is just an illusion. Based on geological time scales of millions and even hundreds of millions of years, mountains turn out to be as transitory as anything else, including you and me.
Any rock, as soon as it begins to be exposed to the atmosphere, will instantly collapse. If you look at a fresh piece of rock or a broken pebble, you will see that the newly formed surface of the rock is often a completely different color than the old one that has been in the air for a long time. This is due to the influence of oxygen contained in the atmosphere, and in many cases, rainwater. Because of them, various chemical reactions occur on the surface of the rock, gradually changing its properties.
Over time, these reactions cause the minerals that hold the rock together to be released, and it begins to crumble. Tiny cracks form in the rock, allowing water to penetrate. When this water freezes, it expands and tears the rock apart from the inside. When the ice melts, such rock will simply fall apart. Very soon the fallen pieces of rock will be washed away by the rains. This process is called erosion.
Muir Glacier in Alaska. The destructive impact of the glacier and the stones frozen into it from below and from the sides gradually causes erosion of the walls and bottom of the valley along which it moves. As a result, long strips of rock fragments form on the ice - so-called moraines. When two neighboring glaciers merge, their moraines also join.
Water is a destroyer.
Pieces of destroyed rock eventually end up in rivers. The current drags them along the river bed and wears them down into the rock that forms the bed itself, until the surviving fragments finally find a quiet refuge at the bottom of a lake or sea. Frozen water (ice) has even greater destructive power. Glaciers and ice sheets drag behind them many large and small rock fragments frozen into their icy sides and bellies. These fragments make deep grooves in the rocks along which glaciers move. A glacier can carry rock fragments that fall on top of it for many hundreds of kilometers.
Sculptures created by the wind
Wind also destroys rocks. This happens especially often in deserts, where the wind carries millions of tiny grains of sand. Sand grains are mostly composed of quartz, an extremely durable mineral. A whirlwind of sand grains hits the rocks, knocking out more and more grains of sand from them.
Often the wind piles up sand into large sand hills, or dunes. Each gust of wind deposits a new layer of sand grains on the dunes. The location of the slopes and the steepness of these sand hills make it possible to judge the direction and strength of the wind that created them.
Glaciers carve deep U-shaped valleys along their path. At Nantfrankon, Wales, the glaciers disappeared in prehistoric times, leaving behind a wide valley that is clearly too large for the small river that now flows through it. The small lake in the foreground is blocked by a strip of particularly strong rock.
Planet Earth is the only known place where life has been found so far, I say for now because perhaps in the future people will discover another planet or satellite with intelligent life living there, but for now Earth is the only place where there is life. Life on our planet is very diverse, from microscopic organisms to huge animals, plants and more. And people have always had the question - How and where did our planet come from? There are many hypotheses. Hypotheses for the origin of the Earth are radically different from each other, and some of them are very difficult to believe.
This is a very difficult question. You cannot look into the past and see how it all began and how it all began to emerge. The first hypotheses of the origin of planet Earth began to appear in the 17th century, when people had already accumulated a sufficient amount of knowledge about space, our planet and the solar system itself. Now we adhere to two possible hypotheses for the origin of the Earth: Scientific - The Earth was formed from dust and gases. Then the Earth was dangerous place for life after for long years evolution, the surface of planet Earth has become suitable for our life: the Earth’s atmosphere is suitable for breathing, a solid surface, and much more. And Religious - God created the Earth in 7 days and settled here all the diversity of animals and plants. But at that time, knowledge was not enough to weed out all other hypotheses, and then there were much more of them:
- Georges Louis Leclerc Buffon. (1707–1788)
He made an assumption that no one would believe now. He suggested that the Earth could have been formed from a piece of the Sun, which was torn off by a certain comet that hit our star.
But this theory was refuted. Edmund Halley, an English astronomer, noticed that our solar system is visited by the same comet at intervals of several decades. Halley even managed to predict the next appearance of the comet. He also found that the comet changes its orbit a little each time, which means it does not have significant mass to tear off a “piece” from the Sun.
- Immanuel Kant. (1724–1804)
Our Earth and the entire solar system were formed from a cold and collapsing dust cloud. Kant wrote an anonymous book where he described his hypotheses about the origin of the planet, but it did not attract the attention of scientists. Scientists by this time were considering a more popular hypothesis put forward by Pierre Laplace, a French mathematician.
- Pierre-Simon Laplace (1749–1827)
Laplace suggested that the solar system was formed from a constantly rotating gas cloud heated to enormous temperatures. This theory is very similar to current scientific theory.
- James Jeans (1877–1946)
A certain cosmic body, namely a star, passed too close to our Sun. The sun's gravity tore some mass out of this star, forming a sleeve of hot material that eventually formed all of our 9 planets. Jeans talked about his hypothesis so convincingly that a short time it conquered the minds of people and they believed that this was the only possible emergence of the planet.
So, we looked at the most famous hypotheses of the origin, they were very unusual and diverse. In our time, they would not even listen to such people, because we now have much more knowledge about our solar system and about the Earth than people knew then. Therefore, hypotheses about the origin of the Earth were based only on the imagination of scientists. Now we can observe and conduct various studies and experiments, but this has not given us a definitive answer about how and from what exactly our planet originated.
How did the Earth appear?
It's so nice to know that planet Earth turned out to be the most suitable for various forms life. Perfect here temperature conditions, enough air, oxygen and safe light. It's hard to believe that once upon a time none of this existed. Or almost nothing but a molten cosmic mass of indeterminate shape, floating in zero gravity. But first things first.
Explosion on a universal scale
Early theories of the origin of the universe
Scientists have put forward various hypotheses to explain the birth of the Earth. In the 18th century, the French claimed that the cause was a cosmic catastrophe resulting from the collision of the Sun with a comet. The British claimed that an asteroid flying past the star cut off part of it, from which it subsequently emerged whole line celestial bodies.
German minds have moved further. They considered a cold dust cloud of incredible size to be the prototype for the formation of planets in the solar system. Later they decided that the dust was hot. One thing is clear: the formation of the Earth is inextricably linked with the formation of all the planets and stars that make up the solar system.
Big Bang
Today, astronomers and physicists are unanimous in their opinion that the Universe was formed after the Big Bang. Billions of years ago, a giant fireball exploded into pieces in outer space. This caused a gigantic ejection of matter, the particles of which had colossal energy.
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Eratosthenes and the circumference of the Earth
It was the power of the latter that prevented the elements from creating atoms, forcing them to repel each other. This was also facilitated by high temperatures (about a billion degrees). But after a million years, space cooled to approximately 4000º. From this moment, the attraction and formation of atoms of light gaseous substances (hydrogen and helium) began.
Over time, they grouped into clusters called nebulae. These were the prototypes of future celestial bodies. Gradually, the particles inside spun faster and faster, increasing in temperature and energy, causing the nebula to shrink. Having reached a critical point, at a certain moment a thermonuclear reaction began, promoting the formation of a nucleus. Thus the bright Sun was born.
The emergence of the Earth - from gas to solid
The young star had powerful gravitational forces. Their influence caused the formation of other planets at different distances from accumulations of cosmic dust and gases, including the Earth. If you compare the composition of different celestial bodies of the solar system, it will become noticeable that they are not the same.
Mercury is mainly composed of a metal that is most resistant to sunlight. Venus and Earth have a rocky surface. But Saturn and Jupiter remain gas giants due to their greatest distance. By the way, they protect other planets from meteorites, pushing them away from their orbits.
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Oxygen in the atmosphere
Formation of the Earth
The formation of the Earth began according to the same principle that underlay the appearance of the Sun itself. This happened approximately 4.6 billion years ago. Heavy metals (iron, nickel) as a result of gravity and compression penetrated into the center of the young planet, forming the core. Heat created all the conditions for a series of nuclear reactions. A separation of the mantle and core occurred.
The heat generated melted and ejected light silicon to the surface. It became the prototype of the first crust. As the planet cooled, volatile gases burst out from the depths. This was accompanied by volcanic eruptions. Molten lava later formed rocks.
Gas mixtures were held at a distance around the Earth by gravity. They formed an atmosphere, initially without oxygen. Encounters with icy comets and meteorites led to the appearance of oceans from condensation of vapors and melted ice. Continents separated and reconnected, floating in a hot mantle. This was repeated many times over almost 4 billion years.
Path to life
While forming, the Earth increased its ability to attract cosmic particles (rocks, asteroids, meteorites, dust). Falling to the surface, they gradually penetrated into the depths (centrifugal forces acted), completely giving up their own energy. The planet was becoming denser. Chemical reactions served as prerequisites for the formation of the first forms of life - single-celled ones.