Message about planet earth 4. Earth is a unique planet! Neighbors of our planet

BASIC DATA ABOUT PLANET EARTH

Planet Earth formed about 4.5 billion years ago.

The Earth is the third planet from the Sun.

Earth is the fifth largest planet in the world and the largest in diameter, mass and density among the terrestrial planets.

Earth's surface area: 510,072,000 km2

Earth mass: 5.9726 1024 kg

The length of the Earth's equator is 40,075 km.

The density of the Earth is higher than any other planet (5.515 g/cm3).

The distance from the Earth to the Sun is almost 150 million km.

It takes planet Earth about 23 hours, 56 minutes and 4.091 seconds to turn around its axis. IN Lately the day shortened by hundredths of a second, indicating that the planet's angular velocity increased. The factors causing this increase have not been established.

The Earth's rotation speed is 107,826 km/h.

The Earth's rotation axis is inclined at an angle of 23.44° relative to the ecliptic plane. It is because of this tilt that we have a change of seasons on planet Earth: summer, winter, spring and autumn.

The Earth is not a perfect sphere; due to the force of rotation, the Earth is actually convex at the equator.

The Earth's core contains hot magma. Not a single drilling rig will be able to reach the core of our planet for at least the next few hundred years.

Our planet's molten iron core creates the Earth's magnetic field. For continuous work magnetic field The Earth is influenced by two factors: its rotation and the impact of the core, the molten mass of which includes nickel and iron.

SATELLITES

Our planet has one natural satellite - .

The fate of the Moon has not yet been clarified. It is not known exactly how it was formed.

The ebb and flow of tides on Earth occur due to the activity of the Moon.

Earth has 2 additional asteroids. They are called 3753 Cruithne and 2002 AA29.

All the planets of the Solar System can be placed between the Earth and the Moon.

PRESENCE OF LIFE

Earth is the only planet where complex life forms exist. It has the necessary amount of water and other conditions that are extremely important for the existence of any form of life.

Throughout the history of the Earth, about 108 billion people have lived on it. Seven billion live here now. And you are one of them.

Only on Earth can we observe three states of water (solid, gaseous, liquid).

ATMOSPHERE

The Earth's atmosphere reaches up to 10,000 kilometers.

Thanks to the Earth's atmosphere, which consists of oxygen, nitrogen and other gases, we are not constantly exposed to falling and radioactive radiation from the sun.

In 2006 it was discovered the ozone hole over Antarctica, which is the largest hole previously discovered.

Every year, about 30,000 tons of interplanetary dust reach the Earth's surface.

CONTINENTS AND ISLANDS

Currently, planet Earth has 6 continents.

List of continents of our planet: Eurasia, North America, South America, .

It is extremely difficult to calculate the exact number of islands on our land, because some islands appear, while others, on the contrary, disappear. There is an approximate figure - about 500,000, but this is only a hypothesis, perhaps there are a little more, and perhaps a little less. But you can name, for example, the 4 largest islands on Earth and these are: New Guinea, the island of Borneo and Madagascar.

Antarctica contains 2/3 of the planet's fresh water reserves.

In the distant future, Africa will “bump into” Europe, resulting in the formation of a giant mountain range.

The plates of the Earth's crust move at a rate of several inches per year, which is approximately equal to the length of a human fingernail growing in a year. On this basis, it can be argued that in 250 million years a new supercontinent will appear on Earth.

The Himalayas are a pattern of tectonic plates moving towards each other.

90% of the earth's ice is stored on one single continent - Antarctica. 2/3 of the planet’s freshwater reserves are “hidden” there.

Over 500 thousand earthquakes occur on our planet every year! But only 20% of them can be felt by people.

OCEANS

About 70% of the Earth's surface is occupied by oceans.

All oceans on earth are connected to each other, so we can assume that there is one giant ocean of the world, consisting of four or five parts.

The existence of four oceans on earth is officially recognized: the Pacific Ocean, the Atlantic Ocean, the Indian Ocean and the fourth - the Arctic Ocean.

At the beginning of the 21st century, the International Hydrographic Organization adopted a division into five parts (the Southern Ocean is added), but at the moment this document still does not have legal force.

The largest ocean on Earth is the Pacific Ocean. Its area is so large that it could easily fit all the continents.

Man has not yet explored 95 percent of the world's oceans.

The longest mountain range on Earth is not on land, but in the oceans. It almost completely encircles the planet.

THE BEST

The highest point on Earth is, rising above the Earth's surface by almost 9 kilometers (8848 meters). It is located in the Himalayas.

The deepest place on Earth is considered to be located in the Pacific Ocean. It is located 10911 meters below sea level.

The lowest temperature recorded on the Earth's surface is -89.2 degrees Celsius. It was registered on July 21, 1983 at Vostok station in Antarctica.

The highest temperature on the Earth's surface is +56.7 Celsius on July 10, 1913 in Death Valley, USA.

The driest hot place on Earth is not the Sahara, but the Atacama Desert. Rain has never been observed in its central part.

A FEW MORE FACTS

According to one popular hypothesis, the Earth once shared its orbit with another planet, which scientists called Theia. Many billions of years ago, these planets collided, and as a result of the greatest catastrophe in its history, the Earth acquired additional mass and received its own satellite.

Earth is the only planet whose name did not come to us from Roman or Greek mythology. It comes from the 8th century Anglo-Saxon word "Erda", meaning "ground" or "soil".

Unlike other planets, the word Earth has its own name in every nation.

One of the most beautiful natural phenomena on our planet arises due to the interaction of charged particles coming from the Sun with the Earth’s magnetic field.

Contrary to popular belief, it is not visible from. However, air pollution in China can be seen from space. In addition, you can see from space.

PLANET EARTH.

Among the celestial bodies existing in infinite space, there is the planet on which we live - Earth. The earth was not always the way we know it now. Like the rest of the planets, it appeared about 5 billion years ago from a rotating cloud of hot gases. At this time, solid particles began to form in it. There were more and more of them, and gradually the cloud thickened, which turned into a hot, dense ball.

The surface of this ball gradually cooled, and finally a hard crust formed. That's what they call it - the earth's crust. Beneath it the Earth still retains heat.

In the youth of our planet, the earth’s crust was thin and fragile, its hot interiors and magma often burst out through volcanic openings. During the eruptions of these numerous volcanoes, hot magma poured onto the surface of the Earth, and with it gases, including water vapor, escaped. Gradually, they formed the air shell of the planet - the atmosphere. As the globe cooled, the steam turned into water, giving rise to the World Ocean, which covered most of the Earth's surface, where life arose about 1.5 billion years ago.

The earth has the shape of a ball. But it's hard to notice. Therefore, in ancient times there were different ideas about the Earth and its shape. The ancient Greeks, Phoenicians and Indians believed that the Earth was flat, like a pancake, and surrounded by mountains on all sides. And above the Earth, on four huge pillars, lies a crystal bowl - the sky. The Indians of North America were sure that the world worked like this: the Earth is a whale swimming among endless waters; the man and woman are the personification of Humanity, and the sky is a soaring mighty eagle. And in Asia and Ancient India it was believed that the Earth was a flat or slightly elongated disk, like a drop on a table, that rested on the backs of four giant elephants (according to the number of cardinal directions). The elephants, in turn, stand on the back of a huge turtle. When elephants get tired and shift from foot to foot, earthquakes occur. In the center of the earth rises Mount Meru - the center of the universe, around which the sun, planets and stars revolve. In Ancient China, they believed that the Earth was a cake with cut off edges. In the Middle Ages, scientists thought that the Earth was covered with a cap on which the stars were mounted.

The first to understand that our Planet has the shape of a ball were the sages and philosophers in Ancient Greece. Already two and a half thousand years ago they knew that the most perfect figure in nature is a ball. This means, they reasoned, that the Earth must be spherical. They managed to find a simple proof: when a ship goes out to sea, we, standing on the shore, first see it in its entirety, then the deck disappears, then the sail slowly sinks. But the ship did not sink to the seabed, it was simply hidden from our view by the convex surface of the Earth. It was not only Europeans who came to the idea that the earth was spherical. The Aztec Indians in North America depicted the planets in the form of balls with which the gods played.

For the first time people began to talk about the Earth as a ball in the third century BC. In the Middle Ages, the church forbade talking about the Earth as a ball, declaring it heresy. So how did people know that the Earth is a sphere? A long time ago people noticed that the higher you rise, the farther you can see. Climbing a tree allows you to see something that you cannot see standing on Earth. And once you climb the mountain, you can see very far away. All this comes from the fact that the Earth is not flat, like a table, but round, like a ball. And a person, compared to the Earth, is too small to see it all at once. So he sees only to the horizon, where heaven and earth meet. You rise higher and the horizon moves away. In addition, the horizon in open areas (in the sea, in the steppe) is always seen as a circle.

Important evidence that the Earth is spherical was the sea voyage of Ferdinand Magellan, a native of Portugal. It took his expedition about three years (1519 - 1522) to go around Earth: go west and return to the same port from the east. After this voyage there was no longer any doubt about the sphericity of the Earth.

Another proof of the sphericity of the Earth was lunar eclipses. During lunar eclipses The Earth's shadow on the Moon is round.

And finally, on April 12, 1961, Yu. A. Gagarin, the first cosmonaut of the Earth, was able to see our planet from the outside, from space, which also provided evidence of the sphericity of the Earth. The picture shows that the Earth has the shape of a ball. The darker areas in the image are water, the lighter areas are land, and the lightest areas are clouds. Scientists have been able to calculate the size of the Earth. It turned out. To go around the globe, you need to travel 40,000 km.

Earth is the third planet from the Sun and the fifth largest of all planets solar system. It is also the largest in diameter, mass and density among the terrestrial planets.

Sometimes referred to as World, Blue Planet, sometimes Terra (from the Latin Terra). The only thing known to man on this moment the body of the Solar System in particular and the Universe in general, inhabited by living organisms.

Scientific evidence indicates that the Earth formed from a solar nebula about 4.54 billion years ago, and shortly thereafter acquired its only natural satellite, the Moon. Life appeared on Earth about 3.5 billion years ago, that is, within 1 billion after its origin. Since then, the Earth's biosphere has significantly changed the atmosphere and other abiotic factors, causing the quantitative growth of aerobic organisms, as well as the formation of the ozone layer, which, together with the Earth’s magnetic field, weakens solar radiation harmful to life, thereby preserving the conditions for the existence of life on Earth.

Radiation caused by the earth's crust itself has decreased significantly since its formation due to the gradual decay of radionuclides in it. The Earth's crust is divided into several segments, or tectonic plates, which move across the surface at speeds of the order of several centimeters per year. Approximately 70.8% of the planet's surface is occupied by the World Ocean, the rest of the surface is occupied by continents and islands. There are rivers and lakes on the continents; together with the World Ocean they make up the hydrosphere. Liquid water, essential for all known life forms, does not exist on the surface of any known planets or planetoids in the Solar System other than Earth. The Earth's poles are covered by a shell of ice that includes Arctic sea ice and the Antarctic ice sheet.

The Earth's interior is quite active and consists of a thick, highly viscous layer called the mantle, which covers a liquid outer core, which is the source of the Earth's magnetic field, and an inner solid core, presumably composed of iron and nickel. physical characteristics The Earth and its orbital motion have allowed life to persist over the past 3.5 billion years. According to various estimates, the Earth will maintain conditions for the existence of living organisms for another 0.5 - 2.3 billion years.

The Earth interacts (is pulled by gravitational forces) with other objects in space, including the Sun and Moon. The Earth revolves around the Sun and makes circles around it full turn approximately 365.26 solar days - a sidereal year. The Earth's rotation axis is inclined by 23.44° relative to the perpendicular to its orbital plane, this causes seasonal changes on the surface of the planet with a period of one tropical year - 365.24 solar days. A day is now approximately 24 hours long. The Moon began its orbit around the Earth approximately 4.53 billion years ago. The Moon's gravitational effect on Earth causes ocean tides. The Moon also stabilizes the tilt of the Earth's axis and gradually slows down the Earth's rotation. Some theories suggest that asteroid impacts led to significant changes in the environment and surface of the Earth, causing mass extinctions in particular various types Living creatures.

The planet is home to millions of species of living beings, including humans. The territory of the Earth is divided into 195 independent states, which interact with each other through diplomatic relations, travel, trade or military action. Human culture has formed many ideas about the structure of the universe - such as the concept of flat earth, the geocentric system of the world and the Gaia hypothesis, according to which the Earth is a single superorganism.

History of the Earth

A modern scientific hypothesis for the formation of the Earth and other planets of the Solar System is the solar nebula hypothesis, according to which the Solar System was formed from a large cloud of interstellar dust and gas. The cloud consisted mainly of hydrogen and helium, which formed after the Big Bang, and heavier elements left behind by supernova explosions. About 4.5 billion years ago, the cloud began to shrink, likely due to the impact of a shock wave from a supernova that erupted several light-years away. As the cloud began to contract, its angular momentum, gravity and inertia flattened it into a protoplanetary disk perpendicular to its axis of rotation. After this, the debris in the protoplanetary disk began to collide under the influence of gravity and, merging, formed the first planetoids.

During the process of accretion, planetoids, dust, gas and debris left over from the formation of the solar system began to merge into ever larger objects, forming planets. The approximate date of formation of the Earth is 4.54±0.04 billion years ago. The entire process of planet formation took approximately 10-20 million years.

The Moon formed later, approximately 4.527 ± 0.01 billion years ago, although its origin has not yet been precisely established. The main hypothesis is that it was formed by accretion from material remaining after a tangential collision of the Earth with an object similar in size to Mars and 10% of Earth's mass (sometimes this object is called “Theia”). This collision released approximately 100 million times more energy than the one that caused the extinction of the dinosaurs. This was enough to evaporate the outer layers of the Earth and melt both bodies. Some of the mantle was thrown into Earth's orbit, which predicts why the Moon is devoid of metallic material and explains its unusual composition. Under the influence of its own gravity, the ejected material took on a spherical shape and the Moon was formed.

The proto-Earth grew larger through accretion and was hot enough to melt metals and minerals. Iron, as well as siderophile elements geochemically related to it, having a higher density than silicates and aluminosilicates, sank to the center of the Earth. This led to the separation of the Earth's inner layers into a mantle and a metallic core just 10 million years after the Earth began to form, producing the Earth's layered structure and shaping the Earth's magnetic field. The release of gases from the crust and volcanic activity led to the formation of the primary atmosphere. The condensation of water vapor, enhanced by ice brought in by comets and asteroids, led to the formation of oceans. The earth's atmosphere then consisted of light atmophilic elements: hydrogen and helium, but contained significantly more carbon dioxide than now, and this saved the oceans from freezing, since the luminosity of the Sun then did not exceed 70% of its current level. About 3.5 billion years ago, the Earth's magnetic field formed, which prevented the solar wind from ravaging the atmosphere.

The surface of the planet was constantly changing over hundreds of millions of years: continents appeared and collapsed. They moved across the surface, sometimes gathering into a supercontinent. About 750 million years ago, the earliest known supercontinent, Rodinia, began to break apart. Later, these parts united into Pannotia (600-540 million years ago), then into the last of the supercontinents - Pangea, which broke up 180 million years ago.

The emergence of life

There are a number of hypotheses for the origin of life on Earth. About 3.5-3.8 billion years ago, the “last universal common ancestor” appeared, from which all other living organisms subsequently descended.

The development of photosynthesis allowed living organisms to use solar energy directly. This led to oxygenation of the atmosphere, which began approximately 2500 million years ago, and in the upper layers to the formation of the ozone layer. The symbiosis of small cells with larger ones led to the development of complex cells - eukaryotes. About 2.1 billion years ago, multicellular organisms appeared and continued to adapt to their surrounding conditions. Thanks to the absorption of harmful ultraviolet radiation by the ozone layer, life was able to begin developing the Earth's surface.

In 1960, the Snowball Earth hypothesis was put forward, arguing that between 750 and 580 million years ago the Earth was completely covered in ice. This hypothesis explains the Cambrian Explosion, a dramatic increase in the diversity of multicellular life forms around 542 million years ago.

About 1200 million years ago the first algae appeared, and about 450 million years ago the first higher plants appeared. Invertebrates appeared during the Ediacaran period, and vertebrates appeared during the Cambrian explosion about 525 million years ago.

There have been five mass extinctions since the Cambrian explosion. The end-Permian extinction event, the largest in the history of life on Earth, resulted in the death of more than 90% of living things on the planet. After the Permian disaster, archosaurs became the most common land vertebrates, from which dinosaurs evolved at the end of the Triassic period. They dominated the planet during the Jurassic and Cretaceous periods. The Cretaceous-Paleogene extinction event occurred 65 million years ago, probably caused by a meteorite impact; it led to the extinction of dinosaurs and other large reptiles, but bypassed many small animals such as mammals, which were then small insectivorous animals, and birds, an evolutionary branch of dinosaurs. Over the past 65 million years, a huge variety of mammal species have evolved, and a few million years ago, ape-like animals gained the ability to walk upright. This allowed the use of tools and facilitated communication, which aided in obtaining food and stimulated the need for a large brain. The development of agriculture, and then civilization, in a short time allowed people to influence the Earth like no other form of life, to influence the nature and numbers of other species.

The last ice age began about 40 million years ago and peaked in the Pleistocene about 3 million years ago. Against the background of long-term and significant changes in the average temperature of the earth's surface, which may be associated with the period of revolution of the Solar system around the center of the Galaxy (about 200 million years), there are also cycles of cooling and warming that are smaller in amplitude and duration, occurring every 40-100 thousand years , having a clearly self-oscillatory character, possibly caused by the action feedback from the reaction of the entire biosphere as a whole, striving to ensure stabilization of the Earth's climate (see the Gaia hypothesis put forward by James Lovelock, as well as the theory of biotic regulation proposed by V.G. Gorshkov).

The last glaciation cycle in the Northern Hemisphere ended about 10 thousand years ago.

Structure of the Earth

According to plate tectonic theory, the outer part of the Earth consists of two layers: the lithosphere, which includes the Earth's crust, and the solidified upper part of the mantle. Below the lithosphere is the asthenosphere, which makes up the outer part of the mantle. The asthenosphere behaves like a superheated and extremely viscous liquid.

The lithosphere is divided into tectonic plates, and seems to float on the asthenosphere. The plates are rigid segments that move relative to each other. There are three types of their mutual movement: convergence (convergence), divergence (divergence) and strike-slip movements along transform faults. Earthquakes, volcanic activity, mountain building, and the formation of ocean basins can occur on faults between tectonic plates.

A list of the largest tectonic plates with sizes is given in the table on the right. Smaller plates include the Hindustan, Arabian, Caribbean, Nazca and Scotia plates. The Australian plate actually merged with the Hindustan plate between 50 and 55 million years ago. Ocean plates move the fastest; Thus, the Cocos plate moves at a speed of 75 mm per year, and the Pacific plate moves at a speed of 52-69 mm per year. The lowest speed of the Eurasian plate is 21 mm per year.

Geographical envelope

The near-surface parts of the planet (upper part of the lithosphere, hydrosphere, lower layers of the atmosphere) are generally called geographical envelope and study geography.

The relief of the Earth is very diverse. About 70.8% of the planet's surface is covered with water (including continental shelves). The underwater surface is mountainous and includes a system of mid-ocean ridges, as well as submarine volcanoes, ocean trenches, submarine canyons, oceanic plateaus and abyssal plains. The remaining 29.2%, not covered by water, includes mountains, deserts, plains, plateaus, etc.

Over 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. Change earth's surface and glaciers, coastal erosion, coral reef formation, collisions with large meteorites.

As continental plates move across the planet, the ocean floor sinks beneath their advancing edges. At the same time, mantle material rising from the depths creates a divergent boundary at mid-ocean ridges. Together, these two processes lead to constant renewal of the material of the oceanic plate. Most of the ocean floor is less than 100 million years old. The oldest oceanic crust is located in the western Pacific Ocean and is approximately 200 million years old. By comparison, the oldest fossils found on land are about 3 billion years old.

Continental plates are composed of low-density material such as volcanic granite and andesite. Less common is basalt, a dense volcanic rock that is the main component of the ocean floor. Approximately 75% of the surface of the continents is covered with sedimentary rocks, although these rocks make up approximately 5% of the earth's crust. The third most common rocks on Earth are metamorphic rocks, formed by the alteration (metamorphism) of sedimentary or igneous rocks under high pressure, high temperature, or both. The most common silicates on the Earth's surface are quartz, feldspar, amphibole, mica, pyroxene and olivine; carbonates - calcite (in limestone), aragonite and dolomite.

The pedosphere is the uppermost layer of the lithosphere and includes soil. It is located on the boundary between the lithosphere, atmosphere, and hydrosphere. Today, the total area of ​​cultivated land is 13.31% of the land surface, of which only 4.71% is permanently occupied by agricultural crops. Approximately 40% of the earth's land area today is used for arable land and pastures, this is approximately 1.3 107 km² of arable land and 3.4 107 km² of grassland.

Hydrosphere

Hydrosphere (from ancient Greek Yδωρ - water and σφαῖρα - ball) is the totality 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 in the solar system. Most of the water is concentrated in the oceans and seas, much less in river networks, lakes, swamps and groundwater. There are also large reserves of water in the atmosphere, in the form of clouds and water vapor.

Some of the water is in a solid state in the form of glaciers, snow cover and permafrost, making up the cryosphere.

The total mass of water in the World Ocean is approximately 1.35·1018 tons, or about 1/4400 of the total mass of the Earth. The oceans cover an area of ​​about 3.618 108 km2 with an average depth of 3682 m, which allows us to calculate the total volume of water in them: 1.332 109 km3. If all this water were evenly distributed over the surface, it would create a layer more than 2.7 km thick. Of all the water on Earth, only 2.5% is fresh, the rest is salty. Most of the fresh water, about 68.7%, is currently contained in glaciers. Liquid water appeared on Earth probably about four billion years ago.

The average salinity of the Earth's oceans is about 35 grams of salt per kilogram sea ​​water(35 ‰). Much of this salt was released by volcanic eruptions or extracted from the cooled igneous rocks that formed the ocean floor.

Earth's atmosphere

Atmosphere is the gaseous shell surrounding planet Earth; consists of nitrogen and oxygen, with trace amounts of water vapor, carbon dioxide and other gases. Since its formation, it has changed significantly under the influence of the biosphere. The appearance of oxygenic 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 all living things from harmful ultraviolet rays. The atmosphere determines the weather on the Earth's surface, protects the planet from cosmic rays, and partially from meteorite bombardments. It also regulates the main climate-forming processes: the water cycle in nature, the circulation of air masses, and heat transfer. Molecules in the atmosphere can capture thermal energy, preventing it from escaping into outer space, thereby increasing the temperature of the planet. This phenomenon is known as the greenhouse effect. The main greenhouse gases are water vapor, carbon dioxide, methane and ozone. Without this thermal insulation effect, the average surface temperature of the Earth would be between minus 18 and minus 23 °C, although in reality it is 14.8 °C, and life would most likely not exist.

The Earth's atmosphere is divided into layers that differ in temperature, density, chemical composition, etc. The total mass of gases that make up the Earth's atmosphere is approximately 5.15 1018 kg. At sea level, the atmosphere exerts a pressure of 1 atm (101.325 kPa) on the Earth's surface. The average air density at the surface is 1.22 g/l, and it quickly decreases with increasing altitude: for example, 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.

The lower part of the atmosphere contains about 80% of its total mass and 99% of all water vapor (1.3-1.5 1013 tons); this layer is called the troposphere. Its thickness varies and depends on the type of climate and seasonal factors: for example, in polar regions it is about 8-10 km, in the temperate zone up to 10-12 km, and in tropical or equatorial regions it reaches 16-18 km. In this layer of the atmosphere, the temperature drops by an average of 6 °C for every kilometer as you move in height. Above is the transition layer - the tropopause, which separates the troposphere from the stratosphere. The temperature here is between 190-220 K.

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

The mesosphere is located at an altitude of 50 to 80 km above the Earth's surface, between the stratosphere and thermosphere. It is separated from these layers by the mesopause (80-90 km). This is the coldest place on Earth, the temperature here drops to −100 °C. At this temperature, the water in the air quickly freezes, forming noctilucent clouds. They can be observed immediately after sunset, but the best visibility is created when it is from 4 to 16 ° below the horizon. In the mesosphere, most of the meteorites that penetrate the earth's atmosphere burn up. From the surface of the Earth they are observed as falling stars. At an altitude of 100 km above sea level there is a conventional boundary between the earth's atmosphere and space - the Karman line.

In the 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 increase in temperature stops, since the air here is very rarefied and weakly absorbs solar radiation.

The ionosphere includes the last two layers. Here, molecules are ionized under the influence of the solar wind and auroras occur.

The exosphere is the outer and very rarefied part of the earth's atmosphere. In this layer, particles are able to overcome the second escape velocity of the Earth and escape into outer space. This causes a slow but steady process called atmospheric dissipation. Mostly particles of light gases escape into space: hydrogen and helium. Hydrogen molecules, which have the lowest molecular weight, can more easily reach escape velocity and escape into space at a faster rate than other gases. It is believed that the loss of reducing agents such as hydrogen was a necessary condition for the possibility of sustainable accumulation of oxygen in the atmosphere. Consequently, the ability of hydrogen to leave the Earth's atmosphere may have influenced the development of life on the planet. Currently, most of the hydrogen entering the atmosphere is converted to water without leaving the Earth, and the loss of hydrogen occurs mainly from the destruction of methane in the upper atmosphere.

Chemical composition of the atmosphere

At the Earth's surface, air contains up to 78.08% nitrogen (by volume), 20.95% oxygen, 0.93% argon and about 0.03% carbon dioxide. The remaining components account for no more than 0.1%: 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, nitrogen becomes the main component of the atmosphere. At an altitude of 600 km, helium predominates, and from 2000 km, hydrogen (“hydrogen corona”) predominates.

Weather and climate

The earth's atmosphere has no definite boundaries; it gradually becomes thinner and more rarefied, moving into outer space. Three-quarters of the atmosphere's mass is contained in the first 11 kilometers from the planet's surface (the troposphere). Solar energy heats this layer near the surface, causing the air to expand and reduce its density. The heated air then rises, and cooler, denser air takes its place. This is how atmospheric circulation arises - a system of closed flows of air masses through the redistribution of thermal energy.

The basis of atmospheric circulation is the trade winds in the equatorial belt (below 30° latitude) and the westerly winds of the temperate zone (at latitudes between 30° and 60°). Ocean currents are also important factors in shaping climate, as is the thermohaline circulation, which distributes thermal energy from equatorial to polar regions.

Water vapor rising from the surface forms clouds in the atmosphere. When atmospheric conditions allow warm, moist air to rise, this water condenses and falls to the surface as rain, snow or hail. Most of the precipitation that falls on land ends up in rivers and eventually returns to the oceans or remains in lakes before evaporating again, repeating the cycle. This water cycle in nature is vital to the existence of life on land. The amount of precipitation that falls per year varies, ranging from several meters to several millimeters, depending on the geographical location of the region. Atmospheric circulation, topological features of the area and temperature changes determine the average amount of precipitation that falls in each region.

The amount of solar energy reaching the Earth's surface decreases with increasing latitude. At higher latitudes, sunlight hits the surface at a sharper angle than at lower latitudes; and it must travel 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 1 degree on either side of the equator. The earth is divided into climatic zones - natural areas having an approximately uniform climate. Climate types can be classified by temperature regime, amount of winter and summer precipitation. The most common climate classification system is the Köppen classification, according to which the best criterion for determining the type of climate is what plants grow in a given area in natural conditions. The system includes five main climate zones (tropical rainforests, deserts, temperate zones, continental climates and polar types), which in turn are divided into more specific subtypes.

Biosphere

The biosphere is a collection of parts of the earth’s shells (litho-, hydro- and atmosphere), which is populated by living organisms, is under their influence and is occupied by the products of their vital activity. The term "biosphere" was first proposed by the Austrian geologist and paleontologist Eduard Suess in 1875. The biosphere is the shell of the Earth populated by living organisms and transformed by them. It began to form no earlier than 3.8 billion years ago, when the first organisms began to emerge on our planet. It includes the entire hydrosphere, the upper part of the lithosphere and the lower part of the atmosphere, that is, it inhabits the ecosphere. The biosphere is the totality of all living organisms. It is home to more than 3,000,000 species of plants, animals, fungi and microorganisms.

The biosphere consists of ecosystems, which include communities of living organisms (biocenosis), their habitats (biotope), and systems of connections that exchange matter and energy between them. On land they are separated mainly by latitude, altitude and differences in precipitation. Terrestrial ecosystems, found in the Arctic or Antarctic, at high altitudes or in extremely dry areas, are relatively poor in plants and animals; species diversity reaches its peak in the tropical rainforests of the equatorial belt.

Earth's magnetic field

To a first approximation, the Earth's magnetic field is a dipole, the poles of which are located next to the geographic poles of the planet. The field forms a magnetosphere, which deflects solar wind particles. They accumulate in radiation belts - two concentric torus-shaped regions around the Earth. Near the magnetic poles, these particles can “precipitate” into the atmosphere and lead to the appearance of auroras. At the equator, the Earth's magnetic field has an induction of 3.05·10-5 T and a magnetic moment of 7.91·1015 T·m3.

According to the "magnetic dynamo" theory, the field is generated in the central region of the Earth, where heat creates the flow of electric current in the liquid metal core. This in turn leads to the emergence of a magnetic field near the Earth. Convection movements in the core are chaotic; magnetic poles drift and periodically change their polarity. This causes reversals in the Earth's magnetic field, which occur on average several times every few million years. The last reversal occurred approximately 700,000 years ago.

The magnetosphere is a region of space around the Earth that is formed when a stream of charged solar wind particles deviates from its original trajectory under the influence of a magnetic field. On the side facing the Sun, its bow shock is about 17 km thick and is located at a distance of about 90,000 km from Earth. On the night side of the planet, the magnetosphere elongates, acquiring a long cylindrical shape.

When high-energy charged particles collide with the Earth's magnetosphere, radiation belts (Van Allen belts) appear. Auroras occur when solar plasma reaches the Earth's atmosphere in the region of the magnetic poles.

Earth's orbit and rotation

It takes the Earth an average of 23 hours 56 minutes and 4.091 seconds (sidereal day) to complete one revolution around its axis. The planet's rotation rate from west to east is approximately 15 degrees per hour (1 degree per 4 minutes, 15′ per minute). This is equivalent angular diameter Sun or Moon every two minutes (the apparent sizes of the Sun and Moon are approximately the same).

The rotation of the Earth is unstable: the speed of its rotation relative to the celestial sphere changes (in April and November, the length of the day differs from the standard by 0.001 s), the axis of rotation precesses (by 20.1″ per year) and fluctuates (the distance of the instantaneous pole from the average does not exceed 15′ ). On a large time scale it slows down. The duration of one revolution of the Earth has increased over the past 2000 years by an average of 0.0023 seconds per century (according to observations over the past 250 years, this increase is less - about 0.0014 seconds per 100 years). Due to tidal acceleration, on average, each next day is ~29 nanoseconds longer than the previous one.

The period of rotation of the Earth relative to the fixed stars, in the International Earth Rotation Service (IERS), is equal to 86164.098903691 seconds according to UT1 version or 23 hours 56 minutes. 4.098903691 p.

The Earth moves around the Sun in an elliptical orbit at a distance of about 150 million km from average speed 29.765 km/sec. The speed ranges from 30.27 km/sec (at perihelion) to 29.27 km/sec (at aphelion). Moving in orbit, the Earth makes a full revolution in 365.2564 average solar days (one sidereal year). From Earth, the movement of the Sun relative to the stars is about 1° per day in an easterly direction. The Earth's orbital speed is not constant: in July (when passing aphelion) it is minimal and amounts to about 60 arc minutes per day, and when passing perihelion in January it is maximum, about 62 minutes per day. The sun and the entire solar system revolve around the center of the galaxy Milky Way in an almost circular orbit at a speed of about 220 km/s. In turn, the Solar System within the Milky Way moves at a speed of approximately 20 km/s towards a point (apex) located on the border of the constellations Lyra and Hercules, accelerating as the Universe expands.

The Moon and the Earth revolve around a common center of mass every 27.32 days relative to the stars. The time interval between two identical phases of the moon (synodic month) is 29.53059 days. When viewed from the north celestial pole, the Moon moves around the Earth counterclockwise. The rotation of all planets around the Sun and the rotation of the Sun, Earth and Moon around their axis occur in the same direction. The Earth's rotation axis is deviated from perpendicular to the plane of its orbit by 23.5 degrees (the direction and angle of inclination of the Earth's axis changes due to precession, and the apparent elevation of the Sun depends on the time of year); The Moon's orbit is inclined 5 degrees relative to the Earth's orbit (without this deviation, there would be one solar and one lunar eclipse each month).

Due to the tilt of the Earth's axis, the height of the Sun above the horizon changes throughout the year. For an observer at northern latitudes in the summer, when the North Pole is tilted toward the Sun, daylight hours last longer and the Sun is higher in the sky. This leads to higher average air temperatures. When North Pole deviates in the opposite direction from the Sun, everything becomes the opposite and the climate becomes colder. Beyond the Arctic Circle at this time there is a polar night, which at the latitude of the Arctic Circle lasts almost two days (the sun does not rise on the day of the winter solstice), reaching six months at the North Pole.

These climate changes (caused by the tilt of the earth's axis) lead to changing seasons. The four seasons are determined by the solstices - the moments when the earth's axis is tilted most towards the Sun or away from the Sun - and the equinoxes. Winter solstice occurs around December 21, the summer equinox around June 21, the spring equinox around March 20, and the autumn equinox around September 23. When the North Pole is tilted towards the Sun, the South Pole is tilted away from it. Thus, when it is summer in the northern hemisphere, it is winter in the southern hemisphere, and vice versa (although the months are called the same, that is, for example, February in the northern hemisphere is the last (and coldest) month of winter, and in the southern hemisphere it is the last (and warmest) ) month of summer).

The tilt angle of the earth's axis is relatively constant over a long period of time. However, it undergoes slight displacements (known as nutation) at intervals of 18.6 years. There are also long-period oscillations (about 41,000 years) known as Milankovitch cycles. The orientation of the Earth's axis also changes over time, the duration of the precession period is 25,000 years; this precession is the cause of the difference sidereal year and tropical year. Both of these movements are caused by the changing gravitational pull exerted by the Sun and Moon on the Earth's equatorial bulge. The Earth's poles move relative to its surface by several meters. This movement of the poles has various cyclic components, which are collectively called quasiperiodic movement. In addition to the annual components of this movement, there is a 14-month cycle called the Chandler movement of the Earth's poles. The speed of the Earth's rotation is also not constant, which is reflected in the change in the length of the day.

Currently, the Earth passes perihelion around January 3 and aphelion around July 4. The amount of solar energy reaching the Earth at perihelion is 6.9% greater than at aphelion, since the distance from the Earth to the Sun at aphelion is 3.4% greater. This is explained by the inverse square law. Because the southern hemisphere is tilted toward the sun around the same time that the Earth is closest to the sun, it receives slightly more solar energy throughout the year than the northern hemisphere. However, this effect is much less significant than the change in total energy due to the tilt of the Earth's axis, and, in addition, most of the excess energy is absorbed by the large amount of water in the southern hemisphere.

For the Earth, the radius of the Hill sphere (sphere of influence of Earth's gravity) is approximately 1.5 million km. This is the maximum distance at which the influence of Earth's gravity is greater than the influence of the gravity of other planets and the Sun.

Observation

The Earth was first photographed from space in 1959 by Explorer 6. The first person to see the Earth from space was Yuri Gagarin in 1961. The crew of Apollo 8 in 1968 was the first to observe the Earth rise from lunar orbit. In 1972, the crew of Apollo 17 took the famous image of the Earth - "The Blue Marble".

From outer space and from the "outer" planets (located beyond the Earth's orbit), it is possible to observe the Earth's passage through phases similar to the Moon's, just as an observer on Earth can see the phases of Venus (discovered by Galileo Galilei).

Moon

The Moon is a relatively large planet-like satellite with a diameter equal to a quarter of Earth's. It is the largest satellite in the solar system relative to the size of its planet. Based on the name of the Earth's Moon, the natural satellites of other planets are also called "moons".

The gravitational attraction between the Earth and the Moon is the cause of the Earth's tides. A similar effect on the Moon is manifested in the fact that it constantly faces the Earth with the same side (the period of the Moon’s revolution around its axis is equal to the period of its revolution around the Earth; see also tidal acceleration of the Moon). This is called tidal synchronization. During the Moon's orbit around the Earth, the Sun illuminates various parts of the satellite's surface, which manifests itself in the phenomenon of lunar phases: the dark part of the surface is separated from the light part by a terminator.

Due to tidal synchronization, the Moon moves away from the Earth by about 38 mm per year. Over millions of years, this tiny change, plus an increase in Earth's day by 23 microseconds per year, will lead to significant changes. For example, in the Devonian (approximately 410 million years ago) there were 400 days in a year, and a day lasted 21.8 hours.

The Moon can significantly influence the development of life by changing the climate on the planet. Paleontological findings and computer models show that the tilt of the Earth's axis is stabilized by the Earth's tidal synchronization with the Moon. If the Earth's rotation axis were to move closer to the ecliptic plane, the planet's climate would become extremely harsh as a result. One of the poles would point directly towards the Sun, and the other would point towards the opposite side, and as the Earth revolves around the Sun, they would change places. The poles would point directly toward the Sun in summer and winter. Planetologists who have studied this situation claim that, in this case, all large animals and higher plants would die out on Earth.

The angular size of the Moon as seen from Earth is very close to the apparent size of the Sun. The angular dimensions (and solid angle) of these two celestial bodies are similar, because although the diameter of the Sun is 400 times larger than the Moon's, it is 400 times farther from the Earth. Due to this circumstance and the presence of a significant eccentricity of the Moon’s orbit, both total and annular eclipses can be observed on Earth.

The most common hypothesis for the origin of the Moon, the giant impact hypothesis, states that the Moon was formed by the collision of the protoplanet Theia (about the size of Mars) with the proto-Earth. This, among other things, explains the reasons for the similarities and differences in the composition of lunar soil and terrestrial soil.

Currently, the Earth has no other natural satellites except the Moon, but there are at least two natural co-orbital satellites - asteroids 3753 Cruithney, 2002 AA29 and many artificial ones.

Near-Earth asteroids

The fall of large (several thousand km in diameter) asteroids to the Earth poses a danger of its destruction, but all those observed in modern era Such bodies are too small for this and their fall is dangerous only for the biosphere. According to popular hypotheses, such falls could have caused several mass extinctions. Asteroids with perihelion distances less than or equal to 1.3 astronomical units that may approach Earth within a distance of less than or equal to 0.05 AU in the foreseeable future. That is, they are considered potentially dangerous objects. In total, about 6,200 objects have been registered that pass at a distance of up to 1.3 astronomical units from the Earth. The danger of their falling onto the planet is regarded as negligible. By modern estimates, collisions with such bodies (according to the most pessimistic forecasts) are unlikely to occur more often than once every hundred thousand years.

Geographical information

Square

• Surface: 510.072 million km²
• Land: 148.94 million km² (29.1%)
• Water: 361.132 million km² (70.9%)

Coastline length: 356,000 km

Using sushi

Data for 2011

• arable land - 10.43%
• perennial plantings - 1.15%
• other - 88.42%

Irrigated lands: 3,096,621.45 km² (as of 2011)

Socio-economic geography

On October 31, 2011, the world's population reached 7 billion people. The UN estimates that the world's population will reach 7.3 billion in 2013 and 9.2 billion in 2050. The bulk of population growth is expected to occur in developing countries. The average population density on land is about 40 people/km2, and varies greatly in different parts of the Earth, with the highest in Asia. The population's urbanization rate is projected to reach 60% by 2030, up from the current global average of 49%.

Role in culture

The Russian word “earth” goes back to the Praslavs. *zemja with the same meaning, which, in turn, continues pra-i.e. *dheĝhōm “earth”.

In English, Earth is Earth. This word continues from Old English eorthe and Middle English erthe. Earth was first used as a name for the planet around 1400. This is the only name of the planet that was not taken from Greco-Roman mythology.

The standard astronomical sign for the Earth is a cross outlined in a circle. This symbol has been used in different cultures for different purposes. Another version of the symbol is a cross on top of a circle (♁), a stylized orb; used as an early astronomical symbol for planet Earth.

In many cultures, the Earth is deified. She is associated with a goddess, a mother goddess, called Mother Earth, and is often depicted as a fertility goddess.

The Aztecs called the Earth Tonantzin - “our mother.” For the Chinese, this is the goddess Hou-Tu (后土), similar to the Greek goddess of the Earth - Gaia. In Norse mythology, the Earth goddess Jord was the mother of Thor and the daughter of Annar. In ancient Egyptian mythology, unlike many other cultures, the Earth is identified with a man - the god Geb, and the sky with a woman - the goddess Nut.

In many religions, there are myths about the origin of the world, telling about the creation of the Earth by one or more deities.

In many ancient cultures, the Earth was considered flat; for example, in the culture of Mesopotamia, the world was represented as a flat disk floating on the surface of the ocean. Assumptions about the spherical shape of the Earth were made by ancient Greek philosophers; Pythagoras adhered to this point of view. In the Middle Ages, most Europeans believed that the Earth was spherical, which was attested to by thinkers such as Thomas Aquinas. Before the advent of space flight, judgments about the spherical shape of the Earth were based on the observation of secondary features and on the similar shape of other planets.

Technological progress in the second half of the 20th century changed the general perception of the Earth. Before space flight, the Earth was often depicted as a green world. Science fiction writer Frank Paul may have been the first to depict a cloudless blue planet (with land clearly visible) on the back of the July 1940 issue of Amazing Stories magazine.

In 1972, the crew of Apollo 17 took the famous photograph of the Earth, called “Blue Marble.” A photograph of the Earth taken in 1990 by Voyager 1 from a great distance from it prompted Carl Sagan to compare the planet to a pale blue dot. Also the Earth was compared to a large spaceship with a life support system that needs to be maintained. The Earth's biosphere has sometimes been described as one large organism.

Ecology

Over the past two centuries, a growing environmental movement has expressed concern about the growing impact of human activities on the Earth's environment. The key objectives of this socio-political movement are to protect natural resources, pollution elimination. Conservationists advocate for sustainable use of the planet's resources and environmental management. This, in their opinion, can be achieved by making changes to government policy and changing the individual attitude of each person. This is especially true for large-scale use of non-renewable resources. The need to take into account the impact of production on environment imposes additional costs, which creates a conflict between commercial interests and the ideas of environmental movements.

Future of the Earth

The future of the planet is closely connected with the future of the Sun. As a result of the accumulation of “spent” helium in the Sun’s core, the star’s luminosity will begin to slowly increase. It will increase by 10% over the next 1.1 billion years, and as a result, the habitable zone of the solar system will shift beyond the current Earth's orbit. According to some climate models, increasing the amount of solar radiation falling on the Earth's surface will lead to catastrophic consequences, including the possibility of complete evaporation of all oceans.

Rising Earth's surface temperatures will accelerate the inorganic circulation of CO2, reducing its concentration to plant-lethal levels (10 ppm for C4 photosynthesis) within 500-900 million years. The disappearance of vegetation will lead to a decrease in oxygen content in the atmosphere and life on Earth will become impossible within a few million years. In another billion years, water will completely disappear from the surface of the planet, and average surface temperatures will reach 70 °C. Most of the land will become unsuitable for life, and it will primarily remain in the ocean. But even if the Sun were eternal and unchanging, the continued internal cooling of the Earth could lead to the loss of most of the atmosphere and oceans (due to decreased volcanic activity). By that time, the only living creatures on Earth will remain extremophiles, organisms that can withstand high temperatures and lack of water.

3.5 billion years from now, the Sun's luminosity will increase by 40% compared to its current level. Conditions on the surface of the Earth by that time will be similar to the surface conditions of modern Venus: the oceans will completely evaporate and fly into space, the surface will become a barren hot desert. This catastrophe will make it impossible for any form of life to exist on Earth. In 7.05 billion years, the solar core will run out of hydrogen. This will lead to the Sun leaving the main sequence and entering the red giant stage. The model shows that it will increase in radius to a value equal to approximately 77.5% of the current radius of the Earth's orbit (0.775 AU), and its luminosity will increase by a factor of 2350-2700. However, by that time the Earth's orbit may increase to 1.4 AU. That is, since the Sun’s gravity will weaken due to the fact that it will lose 28-33% of its mass due to the strengthening of the solar wind. However, studies from 2008 show that the Earth may still be absorbed by the Sun due to tidal interactions with its outer shell.

By then, the Earth's surface will be in a molten state, as temperatures on Earth will reach 1370 °C. Earth's atmosphere is likely to be blown into outer space by the strongest solar wind emitted by the red giant. In 10 million years from the time the Sun enters the red giant phase, temperatures in the solar core will reach 100 million K, a helium flare will occur, and a thermonuclear reaction of the synthesis of carbon and oxygen from helium will begin, the Sun will decrease in radius to 9.5 modern ones. The Helium Burning Phase will last 100-110 million years, after which the rapid expansion of the outer shells of the star will repeat, and it will again become a red giant. Having entered the asymptotic giant branch, the Sun will increase in diameter by 213 times. After 20 million years, a period of unstable pulsations of the star's surface will begin. This phase of the Sun's existence will be accompanied by powerful flares, at times its luminosity will exceed the current level by 5000 times. This will happen because previously unaffected helium residues will enter into the thermonuclear reaction.

In about 75,000 years (according to other sources - 400,000), the Sun will shed its shells, and ultimately all that will remain of the red giant is its small central core - a white dwarf, a small, hot, but very dense object, with a mass of about 54.1% from the original solar one. If the Earth can avoid being absorbed by the outer shells of the Sun during the red giant phase, then it will exist for many billions (and even trillions) of years, as long as the Universe exists, but conditions for the re-emergence of life (at least in its current form) form) will not exist on Earth. As the Sun enters the white dwarf phase, the Earth's surface will gradually cool and plunge into darkness. If you imagine the size of the Sun from the surface of the future Earth, it will look not like a disk, but like a shining point with angular dimensions of about 0°0’9″.

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

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It has excited the minds of scientists for many millennia. There were and are many versions - from purely theological to modern ones, formed on the basis of data from deep space research.

But since no one had a chance to be present during the formation of our planet, we can only rely on indirect “evidence.” Also, the most powerful telescopes provide us with great help in removing the veil from this mystery.

solar system

The history of the Earth is inextricably linked with the emergence and around which it revolves. Therefore, we will have to start from afar. According to scientists, after Big Bang it took one or two billion years for the galaxies to become roughly what they are now. The solar system supposedly arose eight billion years later.

Most scientists agree that it, like all similar cosmic objects, arose from a cloud of dust and gas, since matter in the Universe is distributed unevenly: somewhere there was more of it, and in another place there was less. In the first case, this leads to the formation of nebulae of dust and gas. At some stage, perhaps through external influence, such a cloud contracted and began to rotate. The reason for what happened probably lies in a supernova explosion somewhere in the vicinity of our future cradle. However, if all are formed approximately the same way, then this hypothesis looks dubious. Most likely, having reached a certain mass, the cloud began to attract more particles to itself and compress, and acquired rotational momentum due to the uneven distribution of matter in space. Over time, this swirling blob became increasingly dense in the middle. Thus, under the influence of enormous pressure and rising temperatures, our Sun arose.

Hypotheses from different years

As mentioned above, people have always wondered how planet Earth was formed. The first scientific substantiations appeared only in the seventeenth century AD. At that time, many discoveries were made, including physical laws. According to one of these hypotheses, the Earth was formed as a result of the collision of a comet with the Sun as a residual substance from the explosion. According to another, our system arose from a cold cloud of cosmic dust.

Particles of the latter collided with each other and connected until the Sun and planets were formed. But French scientists suggested that the cloud in question was red-hot. As it cooled, it rotated and contracted, forming rings. The planets were formed from the latter. And the Sun appeared in the center. The Englishman James Jeans suggested that another star once flew past our star. She pulled out the substance from the Sun with her attraction, from which the planets were subsequently formed.

How the Earth was formed

According to modern scientists, the solar system arose from cold particles of dust and gas. The substance was compressed and broke up into several parts. The Sun was formed from the largest piece. This piece rotated and heated up. It became like a disk. Planets, including our Earth, were formed from dense particles on the periphery of this gas-dust cloud. Meanwhile, in the center of the nascent star, under the influence of high temperatures and enormous pressure,

There is a hypothesis that arose during the search for exoplanets (similar to Earth) that the more heavy elements a star has, the less likely it is for life to arise near it. This is due to the fact that their high content leads to the appearance of gas giants around the star - objects like Jupiter. And such giants inevitably move towards the star and push small planets out of orbit.

Date of Birth

The Earth was formed approximately four and a half billion years ago. The pieces rotating around the hot disk became increasingly heavier. It is assumed that initially their particles were attracted due to electrical forces. And at some stage, when the mass of this “coma” reached a certain level, it began to attract everything in the area using gravity.

As in the case of the Sun, the clot began to shrink and heat up. The substance completely melted. Over time, a heavier center formed, consisting mainly of metals. When the Earth was formed, it began to slowly cool, and a crust was formed from lighter substances.

Collision

And then the Moon appeared, but not in the same way as the Earth was formed, again, according to the assumption of scientists and according to the minerals found on our satellite. The Earth, having already cooled down, collided with another slightly smaller planet. As a result, both objects completely melted and turned into one. And the substance ejected by the explosion began to rotate around the Earth. From this came the Moon. It is argued that the minerals found on the satellite differ from those on Earth in their structure: as if the substance was melted and solidified again. But the same thing happened to our planet. And why did this terrible collision not lead to the complete destruction of two objects with the formation of small fragments? There are many mysteries.

Path to life

Then the Earth began to cool again. Again a metal core formed, followed by a thin surface layer. And between them is a relatively mobile substance - the mantle. Thanks to strong volcanic activity, the planet's atmosphere was formed.

Initially, of course, it was absolutely unsuitable for human breathing. And life would be impossible without the appearance of liquid water. It is assumed that the latter was brought to our planet by billions of meteorites from the outskirts of the solar system. Apparently, some time after the Earth was formed, a powerful bombardment occurred, which could have been caused by the gravitational influence of Jupiter. The water was trapped inside minerals, and volcanoes turned it into steam, and it fell out to form oceans. Then oxygen appeared. According to many scientists, this happened thanks to the vital activity of ancient organisms that were able to appear in those harsh conditions. But that's a completely different story. And every year humanity is getting closer and closer to getting an answer to the question of how planet Earth was formed.

The earth is the most big planet earthly group. It is in third place in terms of distance from the Sun and has a satellite - the Moon. Earth is the only planet that is inhabited by living beings. Human civilization is an important factor that has a direct impact on the appearance of the planet. What other characteristics are characteristic of our Earth?

Shape and mass, location

The Earth is a giant cosmic body, its mass is about 6 septillion tons. In its shape it resembles a potato or pear. That is why researchers sometimes call the shape that our planet has a “potatoid” (from the English potato - potato). The characteristics of the Earth as a celestial body, which describe its spatial position, are also important. Our planet is located 149.6 million kilometers from the Sun. For comparison, Mercury is located 2.5 times closer to the luminary than the Earth. And Pluto is 40 times farther from the Sun than Mercury.

Neighbors of our planet

A brief description of the Earth as a celestial body should also contain information about its satellite, the Moon. Its mass is 81.3 times less than that of Earth. The Earth rotates around its axis, which is located at an angle of 66.5 degrees with respect to the orbital plane. One of the main consequences of the Earth's rotation around its axis and its movement in orbit is the change of day and night, as well as seasons.

Our planet belongs to the group of so-called terrestrial planets. Venus, Mars and Mercury are also included in this category. The more distant giant planets - Jupiter, Neptune, Uranus and Saturn - consist almost entirely of gases (hydrogen and helium). All planets that are classified as terrestrial planets rotate around their own axis, as well as along elliptical trajectories around the Sun. Pluto alone, due to its characteristics, is not included by scientists in any group.

Earth's crust

One of the main characteristics of the Earth as a celestial body is the presence of the earth's crust, which, like a thin skin, covers the entire surface of the planet. It consists of sand, various clays and minerals, and stones. The average thickness is 30 km, but in some areas its value is 40-70 km. Astronauts say that the earth's crust is not the most amazing sight from space. In some places it is uplifted by mountain ridges, in others, on the contrary, it falls down in giant pits.

Oceans

A small description of the Earth as a celestial body must necessarily include a mention of the oceans. All pits on Earth are filled with water, which provides shelter for hundreds of living species. However, many more plants and animals can be found on land. If you put all the living creatures that live in water on one scale, and those that live on land on the other, then the heavier cup will turn out to be heavier. Its weight will be 2 thousand times greater. This is very surprising, because the ocean area is more than 361 million square meters. km or 71% of the entire Oceans are a distinctive feature of our planet along with the presence of oxygen in the atmosphere. Moreover, the share of fresh water on Earth is only 2.5%, the rest of the mass has a salinity of about 35 ppm.

Core and mantle

A description of the Earth as a celestial body will be incomplete without a description of its internal structure. The planet's core consists of a hot mixture of two metals - nickel and iron. It is surrounded by a hot and viscous mass that looks like plasticine. These are silicates - substances that are similar in composition to sand. Their temperature is several thousand degrees. This viscous mass is called the mantle. Its temperature is not the same everywhere. Near the earth's crust it is about 1000 degrees, and as it approaches the core it increases to 5000 degrees. However, even in areas close to earth's crust, the mantle can be colder or hotter. The hottest areas are called magma chambers. Magma burns through the crust, and volcanoes, lava valleys, and geysers form in these places.

Earth's atmosphere

Another characteristic of the Earth as a celestial body is the presence of an atmosphere. Its thickness is only about 100 km. Air is a gas mixture. It consists of four components - nitrogen, argon, oxygen and carbon dioxide. Other substances are present in the air in small quantities. Most of the air is located in the layer of the atmosphere that is closest to this part is called the troposphere. Its thickness is about 10 km, and its weight reaches 5000 trillion tons.

Although in ancient times people were unaware of the characteristics of the planet Earth as a celestial body, even then it was assumed that it belonged specifically to the category of planets. How did our ancestors manage to reach such a conclusion? The fact is that they used the starry sky instead of clocks and calendars. Even then it became clear that different luminaries in the sky move in their own way. Some practically do not move from their place (they began to be called stars), while others often change their position relative to the stars. That's why these celestial bodies began to be called planets (translated from Greek, the word “planet” is translated as “wandering”).