Small land message. Structure of land
The land is an object of studying a significant number of land sciences. The study of the Earth as a heavenly body belongs to the region, the structure and composition of the Earth studies geology, the state of the atmosphere - meteorology, a set of manifestations of life on the planet - biology. Geography gives a description of the features of the surface of the surface of the planet - oceans, seas, lakes and year, continents and islands, mountains and valleys, as well as settlements and societies. Education: cities and villages, states, economic districts, etc.
Planetary characteristics
The Earth rotates around the star of the Sun along the elliptical orbit (very close to the circular) at an average speed of 29765 m / s at an average distance of 149,600,000 km for the period, which is approximately equal to 365.24 days. The land has a satellite - which rotates around the sun on an average distance of 384400 km. The slope of the earth axis to the plane of the ecliptic is 66 0 33 "22". The period of circulation of the planet around its axis 23 h 56 min 4.1 s. Rotation around its axis causes a change of day and night, and the tilt of the axis and the appeal around the Sun is a change of time of the year.
The shape of the Earth is a geoid. The average radius of the Earth is 6371.032 km, Equatorial - 6378.16 km, Polar - 6356,777 km. The surface area of \u200b\u200bthe globe is 510 million km², the volume is 1.083 · 10 12 km², the average density is 5518 kg / m³. The mass of the Earth is 5976.10 21 kg. The land has a magnetic and closely connected electrical field. The gravitational field of the Earth determines its close to the spherical shape and the existence of the atmosphere.
According to modern cosmogonic ideas, the Earth formed about 4.7 billion years ago from the gas substance scattered in the protocololar system. As a result of the differentiation of the substance of the Earth, under the action of its gravitational field, in the conditions of heating of the earth's depths there were various in the chemical composition, aggregate state and physical properties of the shell - geospheres: kernel (center), mantle, earth bark, hydrosphere, atmosphere, magnetosphere . In the composition of the Earth, iron prevails (34.6%), oxygen (29.5%), silicon (15.2%), magnesium (12.7%). The earth's crust, mantle and the inner part of the core are solid (the outer part of the core is considered liquid). Pressure, density and temperature increase from the surface of the Earth. Pressure in the center of the planet 3.6 · 10 11 Pa, density of about 12.5 · 10 ³ kg / m ³, temperature in the range from 5000 to 6000 ° C. The main types of terrestrial crust are the mainland and oceanic, in the transition zone from the mainland to the ocean developed the bark of the intermediate structure.
Form of land
The figure of the Earth is idealization by which they try to describe the form of the planet. Depending on the purpose of the description, various models of the shape of the Earth are used.
First approach
The coarsest form of the description of the Earth's figure at the first approximation is the sphere. For most problems of general land, this approximation is sufficient to use in the description or study of some geographic processes. In this case, they reject the flattenness of the planet at the poles as a non-essential remark. The land has one axis of rotation and the equatorial plane - the plane of the symmetry and the plane of the symmetry of the meridians, which characterize it distinguishes it from the infinity of the sets of symmetry of the ideal sphere. The horizontal structure of the geographic shell is characterized by a certain explanation and a certain symmetry relative to the equator.
Second approximation
With the larger approximation, the figure of the Earth is equated to the ellipsoid of rotation. This model characterized by a pronounced axis, the equatorial plane of symmetry and meridional planes, is used in geodesy for calculating the coordinates, building cartographic networks, calculations, etc. The difference between such an ellipsoid is 21 km, a large axis - 6378,160 km, small - 6356.777 km, eccentricity - 1/298, 25. The surface position can be easily theoretically calculated, but it cannot be determined experimentally in kind.
Third approximation
Since the equatorial cross section of the earth is also an ellipse with a difference between the lengths of the semi-axes in 200 m and an eccentricity of 1/30000, the third model is a three-axis ellipsoid. In geographical studies, this model is almost not used, it only indicates a complex internal structure of the planet.
Fourth approximation
Geoid is an equipotential surface that coincides with the average level of the world's ocean, is a geometric point of space points having the same gravity potential. Such a surface has an incorrect compound form, i.e. Not a plane. The level surface at each point is perpendicular to the plumb. The practical importance and importance of this model is that only with a plumb, level, level and other geodesic devices can be traced the position of level surfaces, i.e. In our case, geoid.
Ocean and land
General feature of the structure ground surface lies in the distribution on the mainland and oceans. Most of the land is occupied by the World Ocean (361.1 million km ² 70.8%), land is 149.1 million km ² (29.2%), and forms six mainland (Eurasia, Africa, North America, South America, and Australia) and islands. It rises above the world's ocean level on average 875 m (the highest height of 8848 m - Jomolungma Mountain), the mountains occupy over 1/3 of the sushi surface. The deserts cover approximately 20% of the sushi surface, the forests are about 30%, glaciers - over 10%. The amplitude of heights on the planet reaches 20 km. The average depth of the world's ocean is approximately equal to 3,800 m (the largest depth of 11020 m is a marine groove (vpina) in the Pacific). The volume of water on the planet is 1370 million km ³, the average salinity is 35 ‰ (g / l).
Geological structure
Geological structure of land
The inner core, presumably, has a diameter of 2,600 km and consists of pure iron or nickel, the external core with a thickness of 2250 km from the molten iron or nickel, the mantle of about 2900 km thick consists mainly of solid rocks separated from the earth's crust with the Mochorovich surface. The bark and the top layer of the mantle form 12 main moving blocks, some of them carry continents. The plateau is constantly slowly moving, this movement is called a tectonic drift.
The inner structure and the composition of the "solid" land. 3. It consists of three main geospheres: the earth's crust, mantle and core, which, in turn, is divided into a number of layers. The substance of these geospheres is different in physical properties, condition and mineralogical composition. Depending on the magnitude of the speeds of seismic waves and the nature of their change with the depth of "solid", the land is divided into eight seismic layers: a, in, s, d ", d", e, f and g. In addition, there is a particularly durable layer in the ground The lithosphere and the next, softened layer - the asthenosphere, the ball A, or the Earth Cora, has a variable thickness (in the continental area - 33 km, in the oceanic - 6 km, on average, 18 km).
Under the mountains, the bark is thickened, in the rhythm valleys of the mid-oceanic ridges almost disappears. At the lower boundary of the earth's crust, the surface of Mochorovichich, the speed of seismic waves increase is jumpingly, which is connected mainly with a change in the real composition with a depth, the transition from granites and basalts in ultrasound rocks of the upper mantle. Layers B, C, D ", D" are included in the mantle. Layers E, F and G form the core of the Earth with a radius of 3486 km on the border with the kernel (Gutenberg surface) The speed of longitudinal waves sharply decreases by 30%, and transverse waves disappear, which means that the external kernel (layer E, stretches to a depth of 4980 km) The liquid below the transition layer F (4980-5120 km) is a solid inner core (layer G), in which transverse waves are repaired.
In solid earthly crust, such chemical elements are dominated: oxygen (47.0%), silicon (29.0%), aluminum (8.05%), iron (4.65%), calcium (2.96%), sodium (2.5%), magnesium (1.87%), potassium (2.5%), titanium (0.45%), which are in total amount to 98.98%. The most rare elements are: RO (approximately 2.10 -14%), Ra (2.10 -10%), Re (7.10 -8%), AU (4.3 · 10 -7%), Bi (9 · 10 -7%) etc.
As a result of magmatic, metamorphic, tectonic processes and processes of sedimentation, the earth's crust is sharply differentiated, complex processes of concentration and scattering of chemical elements leading to the formation of various types of breeds.
It is believed that the upper mold in composition is close to ultrabasic rocks in which (42.5%), Mg (25.9%), Si (19.0%) and Fe (9.85%) prevails. Olivine, less pyroxen reigns in mineral attitude. The lower mantle is considered an analogue of stone meteorites (chondrites). The kernel of 3 hours in composition is similar to iron meteorites and contains approximately 80% FE, 9% Ni, 0.6% CO. On the basis of the meteorite model, the average composition of the Earth is calculated, in which Fe (35%), A (30%), Si (15%) and Mg (13%) prevails.
The temperature is one of the most important characteristics of the earth's depths, which make it possible to explain the condition of the substance in various layers and build a common picture of global processes. In wells in wells, the temperature in the first kilometers increases with a depth with a gradient of 20 ° C / km. At a depth of 100 km, where the primary foci of volcanoes are located, the average temperature is slightly lower than the melting point of rocks and is equal to 1100 ° C. At the same time, under the oceans at a depth of 100-200 km, the temperature is higher than in continents, by 100-200 ° C. The density of the substance in the layer with the glybibin 420 km corresponds to the pressure of 1.4 · 10 10 Pa and is identified with the phase transition to olivine, which occurs at a temperature of approximately 1600 ° C. On the border with the nucleus at a pressure of 1.4 · 10 11 Pa and temperature About 4000 ° C silicates are in a solid state, and iron in liquid. In the transition layer F, where iron solidifies, the temperature can be 5000 ° C, in the center of 3 hours - 5000-6000 ° C, i.e., adequate the tape of the Sun.
Atmosphere of land
The atmosphere of the Earth, the total mass of which is 5.15 · 10 15 t, consists of air - mixtures mainly nitrogen (78.08%) and oxygen (20.95%), 0.93% of argon, 0.03% carbon dioxide, The rest is water vapor, as well as inert and other gases. The maximum surface temperature of the sushi 57-58 ° C (in tropical deserts of Africa and North America), the minimum - about -90 ° C (in the central regions of Antarctica).
The atmosphere of the Earth protects everything alive from the destructive effects of cosmic radiation.
Chemical composition of the Earth's Atmosphere : 78.1% - nitrogen, 20 - oxygen, 0.9 - argon, other - carbon dioxide, water vapor, hydrogen, helium, neon.
The atmosphere of the Earth includes :
- troposphere (up to 15 km)
- stratosphere (15-100 km)
- ionosphere (100 - 500 km).
Weather and climate
The lower layer of the atmosphere is called a troposphere. It occurs in phenomena defining the weather. Due to uneven heating of the earth's surface with solar radiation, in the troposphere, the circulation of large air masses incessantly. The main air currents in the Earth's atmosphere is the Passwow in the strip to 30 ° along the equator and the western winds of the moderate belt in the strip from 30 ° to 60 °. Another factor in the transfer of heat is the system of ocean flows.
Water has a permanent cycle on the surface of the earth. After evaporating from the surface of water and sushi, under favorable conditions of water vapor rises up in the atmosphere, which leads to the formation of clouds. Water returns to the surface of the Earth in the form of atmospheric precipitation and flows to the seas and oceans by the year.
The amount of solar energy that the earth is obtained decreases with increasing latitude. The farther from the equator, the less the angle of falling sun ray On the surface, and the greater the distance that the beam must pass in the atmosphere. As a consequence, the average annual temperature at sea level decreases by about 0.4 ° C per degree of latitude. The damage of the Earth is divided into latitudinal belts from about the same climate: tropical, subtropical, moderate and polar. Climate classification depends on temperature and precipitation. The greatest recognition was the classification of Keppen climates, according to which five broad groups are distinguished - wet tropics, desert, wet average latitudes, continental climate, cold polar climate. Each of these groups is divided into specific pidruses.
The influence of a person on the atmosphere of the Earth
Earth's atmosphere is experiencing a significant impact of human vital activity. About 300 million cars annually discharge to the atmosphere of 400 million tons of carbon oxides, more than 100 million tons of carbohydrates, hundreds of thousands of tons of lead. Powerful emission producers in the atmosphere: TPP, metallurgical, chemical, petrochemical, cellulose and other industries, vehicles.
Systematic inhalation of polluted air significantly worsens people's health. Gaseous and dust impurities can have an unpleasant smell air, irritate the mucous membranes of the eyes, the upper respiratory tract and thereby reduce their protective functions, to be the cause of chronic bronchitis and lung diseases. Numerous studies have shown that against the background of pathological deviations in the body (diseases of the lungs, hearts, liver, kidney and other organs), the harmful effects of atmospheric pollution appears stronger. An important environmental problem was the loss of acid rain. Every year, when burning fuel into the atmosphere, up to 15 million tons of sulfur dioxide comes into the atmosphere, which, combined with water, forms a weak solution of sulfuric acid, which together with the rain falls on the ground. Acid rains have a negative effect on people, harvest, structures, etc.
Pollution of atmospheric air may also indirectly affect health and sanitary living conditions of people.
The accumulation in the atmosphere of carbon dioxide can cause climate warming as a result of a greenhouse effect. Its essence lies in the fact that a layer of carbon dioxide dioxide, which freely transfers solar radiation to the ground, will delay returns to the upper layers of the atmosphere of thermal radiation. In this regard, in the lower layers of the atmosphere to increase the temperature, which, in turn, will lead to the melting of glaciers, snow, lifting the level of oceans and seas, flooding a significant part of the sushi.
History
The Earth formed about 4540 million years ago with a disk-shaped protopetrian cloud with other planets of the solar system. The formation of land as a result of accretion lasted 10-20 million years. At first, the Earth was completely molten, but gradually cooled, and a thin solid shell was formed on its surface - the earth's crust.
Soon after the formation of the Earth, approximately 4530 million years ago, the moon was formed. The current theory of the formation of a single natural satellite of the Earth claims that this happened as a result of a collision with a massive celestial body, which was called the name.
The primary atmosphere of the Earth was formed as a result of the degassing of rocks and volcanic activity. From the atmosphere of the condensed water, forming the world ocean. Despite the fact that the sun is 70% lowered by the sun, which is now, geological data show that the ocean is not frozen, which may be associated with the greenhouse effect. Approximately 3.5 billion years ago, the Earth's magnetic field was formed, which defended her atmosphere from the solar wind.
Earth education and the initial stage of its development (about 1.2 billion years) belong to the degeneracy of history. The absolute age of the oldest rocks is over 3.5 billion years old and, starting from this point, it leads to a countdown of the geological history of the Earth, which is divided into two unequal stages: Precambria, which occupies about 5/6 of the total geological summer (about 3 billion years), and plywood covering the last 570 million years. About 3-3.5 billion years ago, as a result of the natural evolution of matter on Earth, life arose, the development of the biosphere - the totality of all living organisms (the so-called living substance), which significantly affected the development of the atmosphere, hydrosphere and geospheres (at least in Parts of a sedimentary shell). As a result of the oxygen catastrophe, the activities of living organisms changed the composition of the atmosphere of the Earth, enriching it with oxygen, which created an opportunity for the development of aerobic living beings.
A new factor that has a powerful impact on the biosphere and even the geosphere - the activity of humanity appeared on Earth after the appearance of human evolution less than 3 million years ago (unity on dating is not achieved and some researchers consider - 7 million years ago). Accordingly, in the process of development of the biosphere, the formation and further development of the noosphere - the shells of the Earth, which is greatly influenced by the human activity.
The high growth rate of the population of the Earth (the number of the earth's population was 275 million in 1000, 1.6 billion in 1900 and approximately 6.7 billion in 2009) and strengthening the influence of human society on the natural environment nominated the problems of rational use of all natural resources and nature conservation.
The land is the third planet from the Sun and the biggest out of the planets of the earth group. At the same time, it is only fifth largest planet in terms of size and mass in the solar system, but it is surprising, the tight of all planets in the system (5,513 kg / m3). It is also noteworthy that the land is the only planet in the solar system, which people themselves were not called in honor of mythological creature - its name comes from the old English word "Ertha", which means the soil.
It is believed that the Earth formed somewhere around 4.5 billion years ago, and is currently the only famous planet, where the existence of life is possible in principle, and the conditions are such that life in literal sense Chisses on the planet.
Throughout the history of mankind, people sought to understand their native planet. However, the learning curve was very and very difficult, with a large number of mistakes made along the way. For example, even before the existence of ancient Romans, the world was understood as flat, and not spherical. The second visual example is the belief that the sun revolves around the Earth. Only in the sixteenth century, thanks to the work of Copernicus, people learned that in fact the earth is simply a planet rotating around the sun.
Perhaps the most important discovery regarding our planet over the past two centuries is that the land is both ordinary and unique place In the solar system. On the one hand, many of its characteristics are pretty ordinary. Take, for example, the size of the planet, its internal and geological processes: its internal structure is almost identical to three other planets of the earth group in the solar system. Almost the same geological processes forming the surface that are characteristic of such planets and many planetary satellites occur on Earth. However, with all the same, the Earth has a simple amount of absolutely unique characteristics, which are straightened to distinguish it from almost all the planets of the earth group today.
One of the necessary conditions for the existence of life on Earth is no doubt its atmosphere. It consists of about 78% nitrogen (N2), 21% oxygen (O2) and 1% argon. Also, there is a completely minor amount of carbon dioxide (CO2) and other gases. It is noteworthy that nitrogen and oxygen are necessary for the creation of deoxyribonucleic acid (DNA) and the production of biological energy, without which the existence of life is impossible. In addition, the oxygen present in the ozone layer of the atmosphere protects the surface of the planet and absorbs harmful solar radiation.
It is curious that a significant amount of oxygen present in the atmosphere is created on Earth. It is formed as a by-product of photosynthesis, when plants turn carbon dioxide from the atmosphere to oxygen. Essentially, this means that without plants, the amount of carbon dioxide in the atmosphere would be much higher, and the oxygen level is significantly lower. On the one hand, if the level of carbon dioxide increases, it is likely that the Earth will suffer from the greenhouse effect as on. On the other hand, if the percentage of carbon dioxide will become even slightly lower, then the decrease in the greenhouse effect would lead a sharp cooling. Thus, the current carbon dioxide level contributes to the ideal range of comfortable temperatures from -88 ° C to 58 ° C.
When observing the Earth from the space, the first thing that rushes into the eyes is the oceans of liquid water. From the point of view of the surface area, the oceans cover approximately 70% of the Earth, which is one of the most unique properties of our planet.
Like the Earth's atmosphere, the presence of liquid water is a necessary criterion for maintaining life. Scientists believe that for the first time life on Earth arose 3.8 billion years ago and it was in the ocean, and the ability to move on land appeared in living beings much later.
Planetologists explain the presence of two reasons on the land of oceans. The first of them is the Earth itself. There is a suggestion that during the formation of the Earth, the atmosphere of the planet was able to capture large volumes of water vapor. Over time, the geological mechanisms of the planet, primarily its volcanic activity, released this water vapor into the atmosphere, after which in the atmosphere, this pair was condensed and fell to the surface of the planet in the form of liquid water. Another version assumes that the source of water was comets that fell on the surface of the Earth in the past, the ice that prevailed in their composition and formed the reservoirs existing on Earth.
Land surface
Despite the fact that most of the surface of the Earth is located under its oceans, the "dry" surface has many distinctive features. When comparing land with other solid bodies in the solar system, its surface is highly different, as there are no crater on it. According to Plantetogors, this does not mean that the land avoided numerous blows of small cosmic telrather indicates that evidence of such impacts were erased. Perhaps there are many geological processes responsible for this, but scientists allocate the two most important - weathelation and erosion. It is believed that in many respects it is the double impact of these factors influenced erasing from the face of the marks from crater.
So weathelation breaks surface structures into smaller pieces, not to mention the chemical and physical methods of atmospheric influence. An example of chemical weathered are acid rain. An example of physical weathering is the abrasion of river beds caused by rocks contained in running water. The second mechanism - erosion, in its essence, is an impact on the relief by the movement of water particles, ice, wind or land. Thus, under the influence of weathering and erosion, the shock craters on our planet were "erased", due to which some features of the relief were formed.
Also, scientists allocate two geological mechanisms, which, in their opinion, helped to form the surface of the Earth. The first such mechanism is volcanic activity - the process of isolating the magma (molten rock) from the depths of the earth through the gaps in its crust. Perhaps, precisely because of volcanic activity, the Earth Bark was changed and the islands were formed (a visual example is the Hawaiian Islands). The second mechanism is determined by the mountain formation or formation of mountains as a result of compression of tectonic plates.
Structure of the planet Earth
Like other planets of the earth group, the land consists of three components: nuclei, mantle and bark. Current science is confident that the core of our planet consists of two separate layers: the inner core of solid nickel and iron and the outer core from the molten nickel and iron. At the same time, the mantle is a very dense and almost completely solid silicate breed, its thickness is about 2,850 km. The bark also consists of silicate breeds and the difference in its thickness. While the continental cortex ranges range from 30 to 40 kilometers in thickness, the ocean bark is much thinner, - just 6 to 11 km.
Another distinguishing feature of the earth relative to the other planets of the earthly group is that its bark is divided into cold, rigid plates that relieve a hotter mantle below. In addition, these plates are in constant motion. Along their borders, two processes known as subduction and spreading are carried out at once. During subduction, two plates come into contact by producing an earthquake and one plate runs on the other. The second process is a separation when two plates depart from each other.
Earth orbit and Rotation
Earth is required about 365 days in order to make a full revolution in orbit around the sun. The length of our year is associated with a large extent with an average orbital distance of the Earth, which is 1.50 x 10 to the degree of 8 km. With such an orbital distance, the sun's light is required on average about eight minutes and twenty seconds to achieve the surface of the Earth.
With an orbital eccentricity.0167 Earth orbit is one of the most circular in the entire solar system. This means that the difference between the perichelium of the Earth and Apcha is relatively small. As a result, such a small difference intensity of sunlight on Earth remains almost unchanged round year. Nevertheless, the position of the Earth on its orbit determines one or another season.
The slope of the land axis is approximately 23.45 °. At the same time, the land is required twenty-four hours to complete one turn around its axis. This is the fastest rotation among the planets of the earth group, but a little slower than all gas planets.
In the past, the land was considered the center of the Universe. 2000 years old, ancient astronomers believed that the Earth is static, and other celestial bodies travel around the circular orbits around it. To such an opinion, they came by observing the obvious movement of the Sun and the planets when observing the Earth. In 1543, Copernicus published his heliocentric model of the solar system, in which the sun is located in the center of our solar system.
The Earth is the only planet in the system that was not called in honor of mythological gods or goddesses (the rest of the seven planets in the solar system were named after Roman gods or goddesses). It meant five planets visible to the naked eye: Mercury, Venus, Mars, Jupiter and Saturn. All the same approach with the names of the ancient Roman gods was used after the opening of uranium and Neptune. The very word "earth" comes from the old English word "Ertha" meaning the soil.
The earth is the most dense planet in the solar system. The density of the Earth differs in each layer of the planet (the core, for example, is more dense than the earth's crust). The average density of the planet is about 5.52 grams per cubic centimeter.
Gravitational interaction between the Earth and causes tides on Earth. It is believed that the moon is blocked by the tidal forces of the Earth, so its period of rotation coincides with the earth and it is addressed to our planet always the same side.
Earth - the third planet from the sun and the fifth size among all the planets of the solar system. It is also the largest in diameter, mass and density among the planets of the earth group.
Sometimes it is referred to as the world, a blue planet, sometimes terra (from lat. Terra). The only well-known person at the moment the body of the solar system in particular and the universe in general, populated by living organisms.
Scientific data indicate that the Earth was formed from the solar nebula about 4.54 billion years ago, and soon after that I had acquired my only natural satellite - the moon. Life appeared on Earth about 3.5 billion years ago, that is, for 1 billion after her occurrence. Since then, the biosphere of the Earth has significantly changed the atmosphere and other abiotic factors, determining the quantitative growth of aerobic organisms, as well as the formation of the ozone layer, which, together with the magnetic field of the Earth, weakens the solar radiation harmful to life, thereby maintaining the living conditions on Earth.
Radiation caused by the earthly crust itself, since its formation, it has significantly decreased due to the gradual decay of the radionuclides in it. The Earth bark is divided into several segments, or tectonic plates that move along the surface with speeds of the order of several centimeters per year. Approximately 70.8% of the surface of the planet occupies the world ocean, the rest of the surface is occupied by the continents and islands. Rivers and lakes are located on the mainland, together with the world ocean, they constitute a hydrosphere. Liquid water required for all known life forms does not exist on the surface of any of the well-known planets and planetoids of the solar system, except the Earth. The Pole of the Earth is covered with an ice shell, which includes the sea ice of the Arctic and Antarctic Ice Shield.
The internal areas of the Earth are quite active and consist of a thick, very viscous layer, called mantium, which covers the liquid external core, which is the source magnetic field Earth and inner solid core, presumably consisting of iron and nickel. The physical characteristics of the Earth and its orbital movement allowed life to continue for the past 3.5 billion years. According to various estimates, the Earth will preserve the conditions for the existence of living organisms for another 0.5 - 2.3 billion years.
The land interacts (attracted by gravitational forces) with other objects in space, including the sun and the moon. The land turns around the sun and makes around it a full turn around for about 365.26 sunny day - a Sideric year. The axis of rotation of the Earth is tilted by 23.44 ° relative to the perpendicular to its orbital plane, it causes seasonal changes on the surface of the planet with a period of one tropical year - 365.24 sunny day. The day now make up about 24 hours. The moon began his appeal in orbit around the Earth approximately 4.53 billion years ago. The gravitational impact of the Moon on Earth is the cause of ocean tides. Also, the moon stabilizes the slope of the earth's axis and gradually slows the rotation of the Earth. Some theories believe that the drops of asteroids led to significant changes in the environment and the surface of the Earth, causing, in particular, mass extinctions of various types of living beings.
The planet is home to millions of living beings, including a person. The territory of the Earth is divided into 195 independent states that interact with each other by diplomatic relations, travel, trade or hostilities. Human culture has formed a lot of ideas about the universe device - such as the concept of flat land, the geocentric system of the world and the GEAS hypothesis, according to which the Earth is a single superorganism.
History of land
The modern scientific hypothesis of the formation of the Earth and other planets of the solar system is the hypothesis of solar nebula, in which the solar system was formed from a large cloud of inter-storage dust and gas. The cloud consisted mainly of hydrogen and helium, which were formed after a large explosion and more heavy elements left by supernova explosions. Approximately 4.5 billion years ago, the cloud began to shrink, which was probably due to the impact of the shock wave from the supernova overlooking several light years. When the cloud began to shrink, its angular momentum, gravity and inertia fightened it into the protoplanetic disk perpendicular to its axis of rotation. After that, the debris in the protoplanet disk under the action of the force of attraction began to face, and, merging, formed the first planetoids.
In the accretion process of planetoids, dust, gas and debris, which remained after the formation of the solar system, began to merge into increasingly large objects, forming planets. Approximate date of earth formation - 4.54 ± 0.04 billion years ago. The whole process of formation of the planet occupied about 10-20 million years.
The moon has been formed later, approximately 4.527 ± 0.01 billion years ago, although its origin is still definitely not established. The main hypothesis states that it was formed by accretion from the substance left after the tangent collision of the Earth with the object, in size to close Mars and weighing 10% of the earth (sometimes this object is called "Tayya"). As a result of this collision, it was released about 100 million times more energy than as a result of the disintegration of dinosaurs. This was enough to evaporate the external layers of the Earth and melting both bodies. Part of the mantle was thrown into the orbit of the Earth, which predicts why the moon is deprived by metal material, and explains its unusual composition. Under the influence of its own gravity, the elevated material took the spherical shape and the moon was formed.
Procentle increased due to accretion, and was routine enough to melt metals and minerals. Iron, as well as geochemically sprinkled siderophilic elements, possessing a higher density than silicates and aluminosilicates, descended to the center of the Earth. This led to the separation of internal layers of land on the mantle and the metal core after only 10 million years after the land began to form, producing a layered structure of the Earth and forming the magnetic field of the Earth. The release of gases from the crust and volcanic activity led to the formation of the primary atmosphere. The condensation of water vapor, amplified by ice, brought by comets and asteroids, led to the formation of oceans. The earth's atmosphere then consisted of lightly atmospil elements: hydrogen and helium, but contained significantly more carbon dioxide than now, and this was a replete ocean from freezing, since the luminosity of the Sun then did not exceed 70% of the current level. Approximately 3.5 billion years ago, the magnetic field of the Earth was formed, which prevented the empty of the atmosphere by the solar wind.
The surface of the planet was constantly changing over hundreds of millions of years: the continents appeared and destroyed. They moved over the surface, sometimes gathering in the supercontinent. Approximately 750 million years ago the earliest of the famous supercontinents - the birthplace - began to split into parts. Later, these parts were united in Pannament (600-540 million years ago), then in the last of the supercontinents - Pangayu, which broke up 180 million years ago.
The emergence of life
There are a number of the hypotheses of the occurrence of life on Earth. About 3.5-3.8 billion years ago, "the last universal overall ancestor" appeared, from which all other living organisms subsequently occurred.
The development of photosynthesis allowed living organisms to use solar energy directly. This led to an oxygenation of the atmosphere, which began approximately 2500 million years ago, and in the upper layers - to the formation of the ozone layer. Symbiosis of small cells with larger led to the development of complex cells - eukaryotes. Approximately 2.1 billion years ago, multicellular organisms appeared, which continued to adapt to the surrounding conditions. Due to the absorption of destructive ultraviolet radiation, the ozone layer was able to start mastering the surface of the Earth.
In 1960, the hypothesis of the Earth-Snowball was put forward, which claims that between 750 and 580 million years ago, the land was completely covered with ice. This hypothesis explains the Cambrian explosion - a sharp increase in the diversity of multicellular living forms of about 542 million years ago.
About 1200 million years ago, the first algae appeared, and approximately 450 million years ago - the first higher plants. Invertebrate animals appeared in the Eidiac period, and vertebrates - during the Cambrian explosion about 525 million years ago.
After the Cambrian explosion there were five mass extinction. The extinction at the end of the Perm period, which is the most massive in the history of life on Earth, led to the death of more than 90% of living beings on the planet. After the Perm catastrophe, the most common ground verteons became Arhozavra, from which dinosaurs occurred at the end of the triad period. They dominated the planet during the Jurassic and Cretaceous Periods. 65 million years ago there was a chalk-Paleogenic extinction, caused, probably a drop in a meteorite; It led to the disappearance of dinosaurs and other major reptiles, but bypassed many small animals, such as mammals, which were then small insectivorous animals, as well as birds that are the evolutionary branch of dinosaurs. During the last 65 million years, a huge number of various types of mammals have developed, and several million years ago, monkey-like animals obtained the ability of straightening. This made it possible to use tools and contributed to communication that helped to extract food and stimulated the need for a big brain. The development of agriculture, and then civilization, in a short time allowed people to influence Earth as no other form of life, affect nature and the number of other species.
The last glacial period began approximately 40 million years ago, his peak falls on Pleistáz about 3 million years ago. Against the background of long and significant changes in the average temperature of the earth's surface, which can be due to the period of circulation of the solar system around the center of the Galaxy (about 200 million years), there are less than the amplitude and duration of cycles of cooling and warming, occurring every 40-100 thousand years. Having an obviously auto-oscillatory nature, possibly caused by the effect of reverse links from the reaction of the entire biosphere as a whole, seeking to ensure the stabilization of the land climate (see Gay hypothesis, nominated by James Lavlock, as well as the theory of biotic regulation proposed by V. G. Gorshkov).
The last cycle of glaciation in the northern hemisphere ended about 10 thousand years ago.
Structure of land
According to the theory of tectonic plates, the outer part of the Earth consists of two layers: lithosphere, including the earth's bark, and the hardened top of the mantle. Under the lithosphere is an asthenosphere, which makes up the outer part of the mantle. Asthenosphere behaves like overheated and extremely viscous liquid. 
The lithosphere is divided into tectonic plates, and as if floating on an asthenosphere. Plates are rigid segments that move relative to each other. There are three types of their mutual movement: convergence (convergence), divergence (discrepancy) and shear movements for transform faults. On faults between the tectonic plates, earthquakes, volcanic activity, the formation, the formation of the ocean varieties can occur.
The list of largest tectonic plates with sizes is shown in the table on the right. Among the slabs of smaller sizes should be noted by the Industan, Arab, Caribbean stoves, the plate of Nask and the stove plate. The Australian stove actually merged with the Industanian between 50 and 55 million years ago. Ocean plates are moving faster; So, the coco plate moves at a speed of 75 mm per year, and the Pacific cooker - at a speed of 52-69 mm per year. The lowest speed of the Eurasian Plate is 21 mm per year.
Geographic shell
The near-surface parts of the planet (the upper part of the lithosphere, the hydrosphere, the lower layers of the atmosphere) are generally called a geographic shell and are studied by geography.
Earth relief is very diverse. About 70.8% of the surface of the planet is covered with water (including continental shelves). The underwater surface is mountainous, includes a system of mid-ocean ridges, as well as underwater volcanoes, oceanic chute, underwater canyons, oceanic plateaus and abissual plains. The remaining 29.2%, uncovered with water, include mountains, deserts, plains, platea, etc.
During the geological periods, the surface of the planet is constantly changing due to tectonic processes and erosion. The relief of tectonic plates is formed under the influence of weathering, which is a consequence of precipitation, temperature fluctuations, chemical influences. The earth's surface and glaciers, coastal erosion, the formation of coral reefs, collisions with major meteorites are changed.
When moving continental plates on planet, the oceanic bottom is immersed under their impending edges. At the same time, the substance of the mantle rising from the depths creates a divergent border on the mid-oceanic ridges. Together, these two processes lead to a constant updating of the material of the oceanic plate. The age of most of the ocean bottom is less than 100 million years. The oldest ocean bark is located in the western part of the Pacific Ocean, and its age is approximately 200 million years. For comparison, the age of the oldest fossils found on land reaches about 3 billion years.
Continental plates consist of low-density material, such as volcanic granite and andhesite. Basalt is less common - dense volcanic rock, which is the main component of the oceanic bottom. Approximately 75% of the surface of the mainland is coated with sedimentary rocks, although these breeds range about 5% of the earth's crust. Third-time prevalence on Earth rocks are metamorphic rock rocks formed as a result of changes (metamorphism) of sedimentary or igneous rocks under the action of high pressure, high temperature or both at the same time. The most common silicates on the surface of the earth are quartz, field spat, amphibole, mica, pyroxen and olivine; Carbonates - calcite (in limestone), aragonit and dolomite.
Pedosphere is the topmost layer of the lithosphere - turns on the soil. It is located on the border between the lithosphere, the atmosphere, hydrosphere. Today, the total area of \u200b\u200bcultured land is 13.31% of the sushi surface, of which only 4.71% are constantly engaged in agricultural crops. Approximately 40% of the earth sushi is used for arable land and pastures, it is approximately 1.3 · 107 km² of arable land and 3.4 · 107 km² pastures.
Hydrosphere
Hydrosphere (from Dr. Greek. YΔωρ - water and σφαῖρα - ball) - a set of all water reserves of the Earth.
The presence of liquid water on the surface of the Earth is a unique property that distinguishes our planet from other objects of the solar system. Most of the water focuses in the oceans and seas, significantly less - in river networks, lakes, swamps and underground waters. Also large water reserves are available in the atmosphere, in the form of clouds and water vapor.
Part of the water is in a solid state in the form of glaciers, snow cover and in the eternal Merzlot, the famous cryosphere.
The total mass of water in the world ocean is approximately 1.35 × 1018 tons, or about 1/4400 on the total mass of the Earth. Oceans cover area of \u200b\u200babout 3,618 · 108 km2 with an average depth of 3682 m, which allows calculating the total volume of water in them: 1.332 · 109 km3. If all this water is uniformly distributed over the surface, then it would be a layer, with a thickness of more than 2.7 km. Of all the water, which is on Earth, only 2.5% falls on fresh, the rest is salty. Most of fresh water, about 68.7%, is currently in glaciers. Liquid water appeared on Earth, probably about four billion years ago.
The average saline of the earth's oceans is about 35 grams of salt on a kilogram of sea water (35 ‰). A significant part of this salt was released with volcanic eruptions or extracted from chilled erupted rocks formed the bottom of the ocean.
Atmosphere of land
The atmosphere is a gas shell surrounding the planet Earth; It consists of nitrogen and oxygen, with trace amounts of water vapor, carbon dioxide and other gases. Since its inception, it has changed significantly under the influence of the biosphere. The appearance of an oxygen photosynthesis 2.4-2.5 billion years ago contributed to the development of aerobic organisms, as well as the saturation of the atmosphere with oxygen and the formation of the ozone layer, which protects everything alive from harmful ultraviolet rays. The atmosphere determines the weather on the surface of the Earth, protects the planet from cosmic rays, and partly - from meteorite bombing. It also regulates the main climate-forming processes: water cycle in nature, circulation of air masses, heat transfer. The atmosphere molecules can capture thermal energy, interfering with it to go into open space, thereby increasing the temperature of the planet. This phenomenon is known as a greenhouse effect. Basic greenhouse gases are considered water vapor, carbon dioxide, methane and ozone. Without this effect of thermal insulation average surface temperature Earth would be from minus 18 to minus 23 ° C, although in reality it is equal to 14.8 ° C, and life most likely would not exist.
The atmosphere of the Earth is divided into layers that differ in temperature, density, chemical composition, etc. The total weight of the gases constituting the earth's atmosphere is approximately 5.15 × 1018 kg. At the sea level, the atmosphere renders pressure on the surface of 1 atm (101,325 kPa). The average air density at the surface is 1.22 g / l, and it is rapidly decreasing with height growth: so, at an altitude of 10 km above sea level, it is no more than 0.41 g / l, and at an altitude of 100 km - 10-7 g / l
At the bottom of the atmosphere contains about 80% of its total mass and 99% of the total water vapor (1.3-1.5 × 1013 tons), this layer is called a troposphere. Its thickness is not sourinak and depends on the type of climate and seasonal factors: so, in the polar regions it is about 8-10 km, in a temperate belt to 10-12 km, and in tropical or equatorial reaches 16-18 km. In this layer atmosphere, the temperature is lowered by an average of 6 ° C per kilometer when moving in height. The above is the transition layer - the tropopause separating the troposphere from the stratosphere. Temperature here is within 190-220 K.
Stratosphere - a layer of atmosphere, which is located at a height of 10-12 to 55 km (depending on weather conditions and season). It accounts for no more than 20% of the entire mass of the atmosphere. For this layer, a decrease in temperature is characterized up to a height of ~ 25 km, followed by an increase on the border with a mesosphere almost to 0 ° C. This boundary is called strato-eyed and is located at an altitude of 47-52 km. The stratosphere marks the greatest concentration of ozone in an atmosphere that protects all living organisms on Earth from the harmful ultraviolet radiation of the Sun. Intensive absorption of solar radiation by the ozone layer and causes a rapid rise in temperature in this part of the atmosphere.
The mesosphere is located at an altitude of 50 to 80 km above the surface of the Earth, between the stratosphere and the thermosphere. It is separated from these layers of mesopaousis (80-90 km). This is the coldest place on Earth, the temperature here is lowered to -100 ° C. At such a temperature, the water contained in the air quickly freezes, forming silver clouds. They can be observed immediately after sunset, but the best visibility is created when it is from 4 to 16 ° below the horizon. Most of the meteorites penetrating into the earth's atmosphere burns in the mesosphere. From the surface of the earth, they are observed as falling stars. At an altitude of 100 km above sea level there is a conditional border between the earth's atmosphere and space - the pocket line.
In a thermosphere, the temperature quickly rises to 1000 K, this is due to the absorption of short-wave solar radiation in it. This is the longest layer of the atmosphere (80-1000 km). At an altitude of about 800 km, the temperature rise stops, since the air here is very cleaned and weakly absorbs solar radiation.
The ionosphere includes the last two layers. Here is the ionization of molecules under the action of solar wind and polar radiances occur.
Exosphere is an external and very sparse part of the earth's atmosphere. In this layer, the particles are able to overcome the second space speed of the Earth and disappear into space. This causes a slow, but a steady process called the atmosphere dissipation (scattering). Space escapes in the main particle of light gases: hydrogen and helium. Hydrogen molecules having the lowest molecular weight can easier reach the second space speed and to flow into the outer space with a faster pace than other gases. It is believed that the loss of reducing agents, for example hydrogen, was a prerequisite for the possibility of sustainable oxygen accumulation in the atmosphere. Consequently, the property of hydrogen leave the atmosphere of the Earth, perhaps affected the development of life on the planet. Currently, most of the hydrogen falling into the atmosphere is converted into water without leaving the earth, and the loss of hydrogen occurs, mainly from the destruction of methane in the upper layers of the atmosphere.
Chemical composition of the atmosphere
At the surface of the Earth, air contains up to 78.08% nitrogen (by volume), 20.95% oxygen, 0.93% of argon and about 0.03% carbon dioxide. The fraction of the remaining components accounts for no more than 0.1%: it is hydrogen, methane, carbon monoxide, sulfur and nitrogen oxides, water vapor, and inert gases. Depending on the time of year, climate and terrain, the atmosphere may include dust, particles of organic materials, ash, soot, etc. above 200 km The main component of the atmosphere becomes nitrogen. At an altitude of 600 km, helium prevails, and from 2000 km - hydrogen ("hydrogen crown").
Weather and climate
The earthly atmosphere does not have certain boundaries, it gradually becomes thinner and more rarellied, moving to outer space. Three quarters of the mass of the atmosphere are contained in the first 11 kilometers from the surface of the planet (troposphere). Solar energy heats up this surface layer, causing expansion of air and reducing its density. Then the heated air rises, and its place occupies a colder and dense air. This arises atmospheric circulation - a system of closed currents of air masses by redistributing thermal energy.
The basis of the circulation of the atmosphere is the trade winds in the equatorial belt (below 30 ° latitude) and the western winds of the moderate belt (in latitudes between 30 ° and 60 °). Sea currents are also important factors in the formation of climate, as well as thermohalin circulation, which distributes thermal energy from the equatorial regions to the polar.
Water steam, rising from the surface, forms clouds in the atmosphere. When atmospheric conditions are allowed to rise with warm wet air, this water condenses and falls on the surface in the form of rain, snow or hail. Most of the atmospheric precipitation dropped into land falls into the river, and ultimately returns to the oceans or remains in the lakes, and then evaporates again, repeating the cycle. This cycle of water in nature is a vital factor for the existence of life on land. The amount of precipitation falling over the year is different, ranging from several meters to a few millimeters depending on geographic location Region. Atmospheric circulation, topological features of terrain and temperature differences determine the average precipitation, which falls in each region.
The amount of solar energy that has achieved the surface of the Earth decreases with increasing latitude. In higher latitudes, sunlight falls on the surface under a sharper corner than low; And he must pass a longer path in the earth's atmosphere. As a result, the average annual air temperature (at sea level) decreases by about 0.4 ° C when moving per 1 degree on both sides of the equator. The earth is divided into climatic belts - natural zones having approximately homogeneous climate. Climate types can be classified by temperature mode, the number of winter and summer precipitation. The most common climate classification system is the classification of Köppen, in accordance with which the best criterion for determining the climate type is what plants grow on this area in natural conditions. The system includes five main climatic zones (wet tropical forests, deserts, temperate belt, continental climate and polar type), which in turn are divided into more specific subtypes.
Biosphere
The biosphere is a combination of parts of the earth's shells (liter, hydro and atmosphere), which is populated by alive organisms, is under their impact and is engaged in products of their livelihoods. The term "biosphere" was first proposed by the Austrian geologist and a paleontologist Eduard Zyus in 1875. The biosphere is a land shell populated by alive organisms and converted by them. It began to form no earlier than 3.8 billion years ago, when the first organisms began to be born on our planet. It includes the entire hydrosphere, the upper part of the lithosphere and the lower part of the atmosphere, that is, inhabit the ecosphere. The biosphere is a totality of all living organisms. More than 3,000,000 species of plants, animals, fungi and microorganisms live in it.
The biosphere consists of ecosystems, which include communities of living organisms (biocenosis), their habitat (biotop), communication systems that carry out the metabolism and energy between them. On land, they are separated mainly by geographic latitudes, height above sea level and differences in precipitation. Ground ecosystems located in the Arctic or Antarctic, at large altitudes or in extremely arid areas, relatively poor plants and animals; A variety of species reaches a peak in wet rainforest equatorial belts.
Magnetic field of land
The magnetic field of the Earth in the first approximation is a dipole whose poles are located next to the geographic poles of the planet. The field forms a magnetosphere that deflects the solar wind particles. They accumulate in radiation belts - two concentric areas in the form of a torus around the Earth. Near the magnetic poles, these particles can "fall out" into the atmosphere and lead to the appearance of polar shine. At the Equator, the magnetic field of the Earth has an induction of 3.05 · 10-5 tons and magnetic moment 7.91 · 1015 TL · M3.
According to the theory of "Magnetic Dynamo", the field is generated in the central region of the Earth, where heat creates the flow of electrical current in the liquid metallic core. This in turn leads to the emergence of the magnetic field. Convection movements in the kernel are chaotic; Magnetic poles drift and periodically change their polarity. This causes an inversion of the magnetic field of the Earth, which arise on average several times every few million years. Last inversion occurred approximately 700,000 years ago.
The magnetosphere is the area of \u200b\u200bspace around the Earth, which is formed when the flow of charged particles of the solar wind deviates from its initial trajectory under the influence of the magnetic field. On the side facing the Sun, the thickness of her head shock wave is about 17 km and it is located at a distance of about 90,000 km from the ground. On the night side of the planet, the magnetosphere is pulled out by purchasing a long cylindrical shape.
When charged high energy particles face the Earth's magnetosphere, the radiation belts (Van Allen belt) appear. Polar radiances occur when solar plasma reaches the atmosphere of the Earth in the region of magnetic poles.
Earth orbit and Rotation
Earth is required on average 23 hours 56 minutes and 4.091 seconds (star day) to make one turn around their axis. The speed of rotation of the planet from the West to the East is approximately 15 degrees per hour (1 degree in 4 minutes, 15 'per minute). This is equivalent to the angular diameter of the Sun or Moon every two minutes (the visible sizes of the sun and the moon are about the same).
The rotation of the Earth is unstable: its speed of rotation relative to the heavenly sphere is changing (in April and November, the duration of the day differs from the reference by 0.001 c), the axis of rotation is precessing (by 20.1 "per year) and fluctuates (removing the instantaneous pole from the average does not exceed 15 ' ). On a large scale - slows down. The duration of one turnover of land increased over the past 2000 years on average by 0.0023 seconds in century (according to observations over the past 250 years this increase is less - about 0.0014 seconds in 100 years). Due to tidal acceleration, on average, every next day turns out to be longer than the previous one on ~ 29 nanoseconds
The period of rotation of the land relative to fixed stars, in the international service of the Earth's rotation (IERS), is 86164,098903691 seconds by UT1 or 23 hours. 56 min. 4.098903691 p.
The Earth moves around the Sun along the elliptical orbit at a distance of about 150 million km at an average speed of 29.765 km / s. Speed \u200b\u200branges from 30.27 km / s (perigelia) to 29.27 km / s (in Aflia). Moving in orbit, the Earth makes a complete turn for 365,2564 average sunny days (one star year). From the Earth, the movement of the Sun relative to the stars is about 1 ° per day in the eastern direction. The speed of the Earth's orbit movement is inconsistent: in July (during the passage of Afhelia) it is minimal and is about 60 corner minutes per day, and when the perichelium passes in January, about 62 minutes per day. The sun and the entire solar system draws around the center of the Milky Way Galaxy in almost a circular orbit at a speed of about 220 km / c. In turn, the solar system in the Milky Way is moving at a speed of approximately 20 km / s towards the point (APEX) located on the border of the constellation Lyra and Hercules, accelerating as the universe expands.
The moon is drawn together with the earth around the common center of the masses every 27.32 days relative to the stars. The time interval between the two identical phases of the moon (synodic month) is 29,53059 days. If you look at the North Pole of the world, the moon moves around the earth counterclockwise. In the same side, the appeal of all the planets around the Sun, and the rotation of the sun, the earth and the moon around their axis. The axis of rotation of the Earth is deflected from perpendicular to the plane of its orbit by 23.5 degrees (direction and angle of inclination of the axis of the Earth axis due to the precession, and the visible elevation of the Sun depends on the time of year); The orbit of the moon is inclined by 5 degrees relative to the orbit of the Earth (there would be one solar and one lunar eclipse without this deviation in each month).
Because of the tilt axis of the Earth, the height of the sun over the horizon changes over a year. For an observer in the northern latitudes in the summer, when an emergency pole is tilted to the Sun, the daylight lasts longer and the sun in the sky is above. This leads to higher average air temperatures. When the North Pole deviates to the opposite side of the sun, everything becomes the opposite and the climate is being done colder. The northern polar circle at this time is the polar night, which lasts almost two days on the latitude of the northern polar circle (the sun does not go on the day of the winter solstice), reaching in the North Pole of the six months.
These climate change (caused by the inclination of the earth's axis) lead to the change of the seasons. Four seasons are determined by solstice - the moments when the earth's axis is maximally tilted towards the Sun or from the Sun, and equinox. Winter solstice occurs around December 21, summer - approximately June 21, a spring equinox - approximately March 20, and autumn - September 23. When the North Pole is tilted to the Sun, South, respectively, is tilted from him. Thus, when in the northern hemisphere, the summer, in South - Winter, and on the contrary (although months are called the same, that is, for example, February in the northern hemisphere - the last (and the coldest) month of winter, and in South - the last (and the most warm ) Summer month).
The angle of inclination of the earth's axis is relatively constant for a long time. However, it undergoes minor shifts (known as nation) with a periodicity of 18.6 years. There are also long-period oscillations (about 41,000 years), known as Milankovich cycles. The orientation of the land axis over time also changes, the duration of the precession period is 25,000 years; This precession is the reason for the difference in the star and the tropical year. Both of these movements are caused by changing attraction, acting on the part of the Sun and the Moon on the equatorial convexity of the Earth. The Poles of the Earth move relative to its surface for several meters. Such a pole movement has a variety of cyclic components, which together are called a quasi-periodic movement. In addition to the one-year components of this movement, there is a 14-month cycle, called the chandler movement of the Earth's poles. The speed of rotation of the Earth is also not constant, which is reflected in the change in the duration of the day.
Currently, the Earth passes the perigelium around January 3, and the aphelies - approximately July 4th. The amount of solar energy reaching the Earth in the perihelion is 6.9% more than in Aflia, since the distance from the ground to the Sun in Aplia has more than 3.4%. This is due to the law of reverse squares. Since the southern hemisphere is tilted in the direction of the Sun at about the same time when the Earth is closest to the Sun, then during the year it gets a little more solar energy than the North. However, this effect is much less significant than the change in the total energy due to the slope of the earth's axis, and, in addition, most of the excess energy is absorbed by a large amount of water of the southern hemisphere.
For the Earth, the radius of the Hill sphere (the sphere of influence of earthly gravity) is approximately 1.5 million km. This is the maximum distance on which the effect of earth gravity is greater than the effect of gravitations of other planets and the sun.
Observation
For the first time, the land was photographed from Space in 1959 by the Explorer-6 apparatus. In 1961, Yuri Gagarin became the first person to see the Earth from Space. The crew of Apollo-8 in 1968 was the first to watch the sunrise of the Earth from the lunar orbit. In 1972, Apollo-17 crew made the famous Earth's shot - "The Blue Marble".
From the open space and from the "external" planets (located behind the Earth), it is possible to observe the passage of land through phases like lunar, as well as the Earth Observer can see the Phases of Venus (Open Galileo Galileem).
Moon
The moon is a relatively large planet satellite with a diameter of a quarter of the earth. This is the biggest, in relation to the size of your planet, satellite of the solar system. By the name of the earth's moon, the natural satellites of other planets are also called "lunas". 
The gravitational attraction between the earth and the moon is the cause of earthly tides and tides. A similar effect on the moon is manifested in the fact that it is constantly drawn to the ground with the same side (the period of turnover of the moon around its axis is equal to the period of its turnover around the Earth; see also tidal acceleration of the moon). This is called tidal synchronization. During the appeal of the moon around the Earth, the Sun illuminates various sections of the satellite surface, which manifests itself in the phenomenon of lunar phases: the dark part of the surface is separated from the light terminator.
Due to the tidal synchronization of the moon, it is removed from the ground by about 38 mm per year. Through millions of years, this tiny change, as well as an increase in the Earth Day by 23 μs per year, will lead to significant changes. So, for example, in Devon (about 410 million years ago), it was 400 days, and the day lasted 21.8 hours.
The moon can significantly affect the development of life by climate change on the planet. Paleontological finds and computer models show that the slope of the earth's axis is stabilized by the tidal synchronization of the Earth with the Moon. If the axis of rotation of the Earth approached the plane of the ecliptic, then as a result, the climate on the planet would become extremely severe. One of the poles would be directed directly in the sun, and the other - in the opposite direction, and as the Earth appeals around the Sun, they would change in places. Poles would be directed right in the sun in summer and winter. Planetologists who studied such a situation argue that, in this case, all major animals and higher plants would die on Earth.
Visible from the Earth the corner size of the moon is very close to the visible size of the sun. The angular sizes (and body angle) of these two celestial bodies are similar, because even though the diameter of the sun and more lunar 400 times, it is 400 times further from the ground. With this circumstance and the presence of a significant eccentricity of the orbits of the moon, both complete and annular eclipses may be observed on Earth.
The most common hypothesis of the origin of the moon, a hypothesis of a giant clash, argues that the moon formed as a result of the collision of the protofable of the thee (about about Mars) with Proto-Earth. This, among other things, explains the reasons for the similarities and differences in the composition of the lunar soil and the earth.
Currently, the Earth has no other natural satellites, except for the moon, but there are at least two natural coal satellites - this is asteroids 3753 cruisers, 2002 AA29 and many artificial.
Asteroids bringing closer to earth
The fall in the land of large (diameter of several thousand km) asteroids is the danger of its destruction, but all similar bodies observed in the modern era for this purpose are too small and their drop is dangerous only for the biosphere. According to common hypotheses, such falls could cause several mass extinction. Asteroids with perihelial distances, smaller or equal to 1.3 astronomical units, which may be closer to the earth, less or equal to 0.05 A in the foreseeable future. e., are considered potentially dangerous objects. In total, about 6,200 facilities are registered, which take up to 1.3 astronomical units from the ground. The danger of their fall on the planet is regarded as negligible. According to modern estimates, clashes with similar bodies (according to the most pessimistic forecasts) are hardly happening more often than once a hundred thousand years.
Geographical information
Area
- Surface: 510,072 million km²
- Susha: 148.94 million km² (29.1%)
- Water: 361.132 million km² (70.9%)
Coastline length: 356,000 km
Using sushi
Data for 2011
- pushnya - 10.43%
- perennial plantings - 1.15%
- other - 88.42%
Watering lands: 3 096 621.45 km² (for 2011)
Socio-economic geography
On October 31, 2011, the population of the Earth reached 7 billion people. According to the UN estimates, the population of the Earth will reach 7.3 billion in 2013 and 9.2 billion in 2050. It is expected that the bulk of population growth will have to develop countries. The average population density is about 40 people / km2, in different parts of the Earth differs greatly, and the highest it is in Asia. According to forecasts, by 2030, the level of urbanization of the population will reach 60%, while now it is 49% on average worldwide.
Role in culture
The Russian word "Earth" dates back to Praslav. * Zemja with the same meaning that, in turn, continues Pra-I.E. * Dheĝhōm "Earth".
IN english language Earth - Earth. This word continues to the ancient English Eorthh and the Middle-Galia Erthe. As the name of the planet Earth was first used for about 1400. This is the only name of the planet that was not taken from Greco-Roman mythology.
Standard Astronomical Sign of Earth - Cross, Final Circle. This symbol was used in various cultures for different purposes. Another version of the symbol is a cross on the top of the circle (♁), a stylized power; Used as an early astronomical symbol of the planet Earth.
In many cultures, the Earth is deified. It is associated with the goddess, the goddess-mother, is called the mother Earth, often depicted as a goddess of fertility.
At Aztec, the land was called the tunnzin - "Our Mother". The Chinese are the goddess of Hou-Tu (后土), similar to the Greek goddess of the Earth - Gay. In the Scandinavian mythology, the goddess of Earth Erod was the mother of Torah and the daughter of Annara. In ancient Egyptian mythology, unlike many other cultures, the Earth rehearse with a man - God GEB, and the sky with a woman - the goddess of the Nut.
In many religions, there are myths about the occurrence of peace, telling about the creation of the Earth with one or more deities.
In a plurality of antique crops, the Earth was considered flat, so, in the culture of Mesopotamia, the world appeared in the form of a flat disk floating over the ocean surface. The assumptions about the spherical form of the Earth were made by the ancient Greek philosophers; Such a point of view was adhered to Pythagores. In the Middle Ages, most Europeans believed that the Earth is shaped the shape of a ball, which was witnessed by such a thinker as Thomas Akvinsky. Before the appearance of space flights, judgments about the ferrous form of the Earth were based on the observation of secondary signs and on the similar form of other planets.
Technical progress of the second half of the 20th century has changed the overall perception of the Earth. Before the start of space flights, the Earth often depicted as a green world. Frank Frank Paul, perhaps the first portrayed a cloudless blue planet (with a clearly dedicated land) on the turnover of the July issue of Amazing Stories magazine in 1940.
In 1972, the crew of Apollo-17 was made by the famous photo of the Earth, called "Blue Marble" (Blue Marble). Earth snapshot made in 1990 by Voyager-1 with a huge distance from her distance, prompted Karl Sagan to compare the planet with a pale blue dot (Pale Dot). Also, the land was compared with a large cosmic ship with a system of life support that needs to be maintained. The Earth's biosphere was sometimes described as one big body.
Ecology
In the past two centuries, a growing environmental protection is concerned about the growing influence of human activity to the nature of the Earth. The key tasks of this socio-political movement are the protection of natural resources, the elimination of pollution. Nature defenders advocate environmentally rational use of planet resources and environmental management. This, in their opinion, can be achieved by making changes to state policy and a change in the individual relations of each person. This is especially true for the large-scale use of non-renewable resources. The need to account for the impact of production on the environment imposes additional costs, which leads to the emergence of conflict between the commercial interests and ideas of environmental movements.
Future land
The future of the planet is closely connected with the future sun. As a result of accumulation in the core of the Sun "spent" helium, the luminosity of the star will begin slowly grow. It will increase by 10% over the next 1.1 billion years, and as a result of this, the inhabited zone of the solar system will shift outside the modern earth orbit. According to some climatic models, an increase in the amount of solar radiation falling on the surface of the Earth will lead to disastrous consequences, including the possibility of full evaporation of all oceans. 
Increasing the surface temperature of the Earth will speed up the inorganic circulation of CO2 by reducing its concentration to death for levels of level (10 ppm for C4-photosynthesis) for 500-900 million years. The disappearance of vegetation will lead to a decrease in the oxygen content in the atmosphere and life on Earth will be impossible for several million years. Even after a billion years, water from the surface of the planet will disappear completely, and the average surface temperatures are reached 70 ° C. Most of the land will become unsuitable for the existence of life, and it must first remain in the ocean. But even if the sun was forever and invariably, then the continued inner cooling of the Earth could lead to the loss of most of the atmosphere and oceans (due to the decrease in volcanic activity). By that time, extremophils will remain the only alive creatures on Earth, organisms capable of withstanding high temperature and lack of water.
After $ 3.5 billion years of summer, the luminosity of the Sun will increase by 40% compared with the current level. The conditions on the surface of the Earth will be similar to the surface conditions of modern Venus: the oceans will completely evaporate and disappear into space, the surface will become a fruitless redden desert. This catastrophe will make it impossible to exist any forms of life on Earth. After 7.05 billion years, hydrogen reserves will end in the sunny core. This will lead to the fact that the sun will come down from the main sequence and will turn into the stage of the Red Giant. The model shows that it will increase in a radius to a value of approximately 77.5% of the current radius of the Earth orbit (0.775 a. E.), And its luminosity increases at 2350-2700 times. However, by that time the Earth's orbit may increase to 1.4 a. e., since the attraction of the Sun will weaken due to the fact that it will lose 28-33% of its mass due to the strengthening of the solar wind. However, 2008 studies show that the Earth is possible will still be absorbed by the Sun due to tidal interactions with its outer shell.
By that time the surface of the earth will be in the molten state, since the temperature on the ground is reached 1370 ° C. The atmosphere of the Earth is likely to be carried out into the outer space with the strongest solar wind, emitted by a red giant. After 10 million years since the sun, the sun will enter the phase of the red giant, the temperature in the solar core will reach 100 million k, the helium flash will occur, and the thermonuclear carbon synthesis and oxygen reaction will begin, the sun will decrease within a radius to 9.5 modern. The Helium Burning Phase stage will last 100-110 million years, after which the rapid expansion of the external shells of the star will repeat, and it will again become a red giant. Going to the asymptotic branch of the giants, the sun will increase in diameter of 213 times. After 20 million years, the period of unstable ripples of the star surface will begin. This phase of the existence of the Sun will be accompanied by powerful outbreaks, at times its luminosity will exceed the modern level 5000 times. This will occur from the fact that previously affected helium residues will be taken to thermonuclear reaction.
After about 75,000 years (according to other sources - 400,000) the sun will reset the shell, and ultimately only its small central kernel will remain from the red giant - white dwarf, small, hot, but very dense object, with a mass of about 54.1% From the initial solar. If the earth will be able to avoid the absorption by external shells of the Sun during the phase of the Red Giant, it will exist many more billions (and even trillions) years, until the Universe has been to exist, but the conditions for the re-emergence of life (at least in its current The form) on earth will not. With the entry of the sun in the phase of white dwarf, the surface of the earth will gradually cool and plunge into darkness. If you present the sizes of the sun from the surface of the future of the future, it will not look like a disk, but as a shining point with angular sizes about 0 ° 0'9. "
A black hole with a mass equal to the earth will have a Schwarzschild radius of 8 mm.
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Hello readers! Cool planet with us, isn't it? She is beautiful and loved. Today, in this article, I would like to tell you about what our planet consists of, what its form, temperature, composition, size and some more other interesting things ...
Earth, on this planet we live, she is the fifth of the big planets in and the third from the sun.
On earth, generally favorable ,
many natural resources, and maybe it is the only planet on which life exists.
Active geodynamic processes occurring in the depths of the Earth are manifested in building the oceanic bark and its further opening, earthquakes, eruptions, etc.
Form and size.
More than 2000 years already as approximate contours and the size of the Earth are known. Greek scientist pretty accurately calculated the radius of the Earth in the III of Art. BC e. Nowadays it is already known that the polar radius of the Earth is about 12,711 km., And the equatorial radius is 12,754 km.
The surface area of \u200b\u200bthe Earth is about 510.2 million km 2, of which 361 million km 2 are water.The land volume is approximately 1121 billion km 3. Due to the rotation of the planet, the centrifugal force arises, which is maximum in the equator and decreases towards the poles, this rotation causes the irregularities of the radius of the Earth.
If only one strength was operated on Earth, then all items on the surface would fly into space, but thanks to the strength of earthly attraction, this does not occur.
Gravity.
Gravity, or the power of earthly attraction, holds the atmosphere near the earth's surface, and the moon in orbit. With a height, the power of earthly attraction decreases.The state of weightlessness, which is felt by the astronauts, is explained by this circumstance.
Due to the rotation of the Earth and the centrifugal force, the gravity on its surface is somewhat reduced. Acceleration of free falling objects, the value of which is 9.8 m / s, due to the force of earthly attraction.
By difference in gravity in different areas, the heterogeneity of the earth's surface leads. Information on the inner structure of the Earth allows to obtain measurement of weight strength.
Mass and density.
The mass of the Earth is approximately 5976 ∙ 10 21 tons. For comparison, the mass of the Sun is more than 333 thousand times, and the mass of Jupiter is 318 times. But on the other hand, the mass of the Earth exceeds the mass of the moon of 81.8 times. The density of the Earth virures from an extremely high in the center of the planet, to a minor in the upper layers of the atmosphere.
Knowing the mass and volume of land, scientists calculated that its average density is approximately 5.5 times greater than the density of water. Granite is one of the most common fossils on the surface of the earth, its density is 2.7 g / cm 3, the density in the mantle varies from 3 to 5 g / cm 3, within the nucleus - from 8 to 15 g / cm 3. In the center of the Earth, it can reach 17 g / cm 3.
Conversely, air density near the ground surface is approximately 1/800 water density, and in the upper layers of the atmosphere it is very small.
Pressure.
At the sea level, the atmosphere has pressure of 1 kg / cm 2 (pressure in one atmosphere), and it decreases with height. Approximately 2/3 decreases pressure at an altitude of about 8 km. Inside the Earth, pressure is growing rapidly: on the border of the nucleus it is about 1.5 million atmospheres, and its center is up to 3.7 million atmospheres.
Temperatures.
On the ground, the temperature is very virgin. For example, in El - Azizi (Libya), a record high temperature of 58 ° С (September 13, 1922) was registered, and at the East station near the Southern Pole Antarctica, the record low - 89.2 ° C (July 21, 1983 .).
In the depth, the temperature rises by 0.6 ° C every 18 m, then this process slows down. The earth's core, placed in the center of the Earth, is kept to a temperature of 5000 - 6000 ° C.
The average air temperature in the near-surface atmosphere ball is 15 ° C, it decreases gradually in the troposphere, and above (starting from the stratosphere) changes in the wide boundaries of dependence on absolute height.
Cryosphere is the shell of the Earth, as a rule, the temperature in the boundaries of which is below 0 ° C. At high latitudes, it begins with the sea level, and in the tropics - at an altitude of about 4500 m. The cryosphere in the suplar areas on the mainland can stretch a few tens of kilometers below from the earth's surface, forming the horizon.
So I told you the most important facts about the Earth, as if, from the inside. On the other side with which we usually never thought. It was a brief description of Earth. I hope that this article has become a response to your searches. 🙂
Earth - a unique planet!Of course, this is true in our solar system and not only. No one observed by scientists does not think that there are other planets like the Earth.
The land is the only planet rotating around our sun, on which, as we know, there is life.
Like no other planet, our green vegetation is covered with a huge blue ocean containing more than a million islands, hundreds of thousands of streams and rivers, the huge masses of the earth, which are called continents, mountains, glaciers and deserts that produce very diverse colors and textures.
Some forms of life can be found in almost every ecological niche on the surface of the Earth. Even in very cold Antarctica, enduring microscopic beings flourish in ponds, tiny outless insects live in stains of moss and lichens, plants grow and bloom every year. From the top of the atmosphere to the bottom of the oceans, from the cold part of the poles to the warm part of the equator - life flourishes. To this day, there were no signs of life on any other planet.
The land is huge in size, about 13,000 km in diameter, and weighing about 5.98 1024 kg. The land on average is 150 million km from the sun. If the Earth goes much faster, in its 584 million kilometer travel around the sun, her orbit will become more, and it will move on from the sun. If it is too far from a narrow inhabitable zone, all life will cease to exist on Earth.
If this trip becomes a little slower in your orbit, the Earth will move closer to the sun, and if it will move too close, all life will also die. The land travels around the Sun for 365 days, 6-hours, 49-minute and 9.54 seconds (Siderician year), corresponds to more than a thousandths of a second!
If the average annual temperature on the surface of the Earth will change only a few degrees or so, most of the life on it, ultimately, will become fried or frozen.This change will violate water-glacial relations and other important balances, with catastrophic results. If the earth will rotate slower than its axis, all life will die in time, or by freezing at night due to lack of heat from the sun or by burning during the day from too large number Heat.
Thus, our "normal" processes on Earth is undoubtedly unique among our solar system, and, according to what we know, in the whole Universe:
1. It is the inhabited planet. This is the only planet in the solar system that supports life. All forms of life directly from the smallest microscopic organisms to huge land and marine animals.
2. Its distance from the Sun (150 million kilometers) It is advisable to give it an average temperature of 18 to 20 degrees Celsius. It's not so hot, both in Mercury and Venus, and it is as cold as on Jupiter or Pluton.
