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

Sometimes referred to as the World, the Blue Planet, sometimes Terra (from lat. Terra). The only known to man at the moment is 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 the 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 occurrence. 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 significantly decreased since its formation due to the gradual decay of radionuclides in it. The Earth's crust is divided into several segments, or tectonic plates, that move across the surface at speeds of the order of a few 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. On the continents there are rivers and lakes, 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 of the known planets and planetoids of the solar system, except for Earth. The Earth's poles are covered by an ice shell, which includes Arctic sea ice and the Antarctic ice sheet.

The inner regions of the Earth are quite active and consist of a thick, very viscous layer called the mantle, which covers a liquid outer core, which is the source of the Earth's magnetic field, and a solid inner core, supposedly composed of iron and nickel. The physical characteristics of 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 retain the conditions for the existence of living organisms for another 0.5 - 2.3 billion years.

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

The planet is home to millions of species of living beings, including humans. The territory of the Earth is divided into 195 independent states that interact with each other through diplomatic relations, travel, trade or military actions. Human culture has formed many ideas about the structure of the universe - such as the concept of a 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

The modern scientific hypothesis of 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 were formed after the Big Bang and heavier elements left behind by supernova explosions. Approximately 4.5 billion years ago, the cloud began to shrink, which was probably due to the impact of a shock wave from a supernova that broke out at a distance of several light years. 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 that, the fragments in the protoplanetary disk began to collide under the action of gravity, and, merging, formed the first planetoids.

In 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 the 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 says that it was formed by accretion from the material left after the tangential collision of the Earth with an object similar in size to Mars and with a mass of 10% of the Earth (sometimes this object is called "Theia"). This collision released about 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. Part of the mantle was ejected 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 expanded by 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, descended towards 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 forming the Earth's magnetic field. The release of gases from the crust and volcanic activity led to the formation of the primary atmosphere. Condensation of water vapor, enhanced by ice brought 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 much more carbon dioxide than now, and this saved the oceans from freezing, since the luminosity of the Sun then did not exceed 70% of the current level. Approximately 3.5 billion years ago, the Earth's magnetic field formed, which prevented the devastation of the atmosphere by the solar wind.

The surface of the planet has been constantly changing for hundreds of millions of years: continents have appeared and collapsed. They moved across the surface, sometimes gathering into a supercontinent. Around 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 the oxygenation of the atmosphere, which began about 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. Approximately 2.1 billion years ago, multicellular organisms appeared that continued to adapt to environmental conditions. Thanks to the absorption of harmful ultraviolet radiation by the ozone layer, life was able to begin the development of the Earth's surface.

In 1960, the Snowball Earth hypothesis was put forward, stating that between 750 and 580 million years ago, the Earth was completely covered in ice. This hypothesis explains the Cambrian explosion - a sharp increase in the diversity of multicellular life forms about 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 in 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 extinction at the end of the Permian 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 Permian catastrophe, archosaurs became the most common terrestrial vertebrates, from which dinosaurs descended at the end of the Triassic period. They dominated the planet during the Jurassic and Cretaceous periods. 65 million years ago there was a Cretaceous-Paleogene extinction, probably caused by a meteorite fall; 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 the dinosaurs. Over the past 65 million years, a huge variety of mammalian species has evolved, and several million years ago, ape-like animals acquired the ability to walk upright. This enabled the use of tools and promoted communication, which aided in foraging for 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 number 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 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 smaller cycles of cooling and warming in amplitude and duration that occur every 40-100 thousand years. , which are clearly self-oscillating in nature, possibly caused by the action of feedback from the reaction of the entire biosphere as a whole, seeking to stabilize 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 cycle of glaciation in the Northern Hemisphere ended about 10,000 years ago.

Earth structure

According to the theory of tectonic plates, the outer part of the Earth consists of two layers: the lithosphere, which includes the earth's crust, and the hardened upper part of the mantle. Under the lithosphere is the asthenosphere, which makes up the outer part of the mantle. The asthenosphere behaves like an overheated and extremely viscous fluid.

The lithosphere is divided into tectonic plates, and, as it were, floats on the asthenosphere. Plates are rigid segments that move relative to each other. There are three types of their mutual movement: convergence (convergence), divergence (divergence) and shear movements along transform faults. On faults between tectonic plates, earthquakes, volcanic activity, mountain building, and the formation of ocean depressions can occur.

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

Geographic envelope

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

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

During 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, and chemical influences. Change the earth's surface and glaciers, coastal erosion, the formation of coral reefs, collisions with large meteorites.

As continental plates move across the planet, the ocean floor sinks under their advancing edges. At the same time, mantle matter rising from the depths creates a divergent boundary at mid-ocean ridges. Together, these two processes lead to a 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 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 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 as a result of the transformation (metamorphism) of sedimentary or igneous rocks under the influence of 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, the topmost layer of the lithosphere, includes the soil. It is located on the border between the lithosphere, atmosphere, hydrosphere. Today, the total area of ​​cultivated land is 13.31% of the land surface, of which only 4.71% is permanently occupied by crops. Approximately 40% of the earth's land area today is used for arable land and pastures, which is approximately 1.3 x 107 km² of arable land and 3.4 x 107 km² of pasture.

Hydrosphere

Hydrosphere (from other Greek Yδωρ - water and σφαῖρα - ball) - the totality of all the water reserves of the Earth.

The presence of liquid water on the Earth's surface 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.

Part 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 makes it possible to calculate the total volume of water in them: 1.332 109 km3. If all this water was evenly distributed over the surface, then a layer would be obtained, more than 2.7 km thick. Of all the water that is on Earth, only 2.5% is fresh, the rest is salty. Most of the fresh water, about 68.7%, is currently in glaciers. Liquid water appeared on Earth probably about four billion years ago.

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

Earth's atmosphere

Atmosphere - the gaseous shell that surrounds the planet Earth; It is composed 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 emergence 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 partly from meteorite bombardments. It also regulates the main climate-forming processes: the water cycle in nature, the circulation of air masses, and heat transfer. Atmospheric molecules can capture thermal energy, preventing it from escaping into outer space, thereby raising the temperature of the planet. This phenomenon is known as the greenhouse effect. The main greenhouse gases are considered to be water vapour, 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 rapidly 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 it is 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 the 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 up. Above is a transitional layer - the tropopause, which separates the troposphere from the stratosphere. The temperature here is in the range of 190-220 K.

Stratosphere - a layer of the atmosphere, which is located at an altitude of 10-12 to 55 km (depending on weather conditions and seasons). It accounts for no more than 20% of the total mass of the atmosphere. This layer is characterized by a decrease in temperature to a height of ~25 km, followed by an increase at the boundary 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. Intensive 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 the 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 contained 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. Most of the meteorites that enter the earth's atmosphere burn up in the mesosphere. From the surface of the Earth, they are observed as shooting stars. At an altitude of 100 km above sea level, there is a conditional 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 temperature rise stops, because the air here is very rarefied and weakly absorbs solar radiation.

The ionosphere includes the last two layers. Molecules are ionized here under the action of the solar wind and auroras occur.

The exosphere is the outermost and very rarefied part of the earth's atmosphere. In this layer, particles are able to overcome the second cosmic velocity of the Earth and escape into outer space. This causes a slow but steady process called dissipation (scattering) of the atmosphere. It is mainly particles of light gases that 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 a sustainable accumulation of oxygen in the atmosphere. Therefore, 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 that enters 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.

The chemical composition of the atmosphere

At the surface of the Earth, the 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%: these are hydrogen, methane, carbon monoxide, sulfur and nitrogen oxides, water vapor, and inert gases. Depending on the season, 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").

Weather and climate

The earth's atmosphere has no definite boundaries; it gradually becomes thinner and rarer, passing into outer space. Three quarters of the mass of the atmosphere is contained in the first 11 kilometers from the surface of the planet (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 is replaced by colder, denser air. This is how the circulation of the atmosphere arises - a system of closed currents of air masses through the redistribution of thermal energy.

The basis of atmospheric circulation is the trade winds in the equatorial zone (below 30° latitude) and the westerly winds of the temperate zone (in latitudes between 30° and 60°). Sea currents are also important factors in shaping the 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, and then evaporates again, repeating the cycle. This water cycle in nature is a vital factor for the existence of life on land. The amount of precipitation falling during the year is different, ranging from a few meters to a few millimeters, depending on the geographical location of the region. Atmospheric circulation, topological features of the area and temperature differences 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 zones that have an approximately uniform climate. Climate types can be classified according to the temperature regime, the 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 under natural conditions. The system includes five main climatic zones (tropical rainforests, deserts, temperate zone, continental climate and polar type), which in turn are divided into more specific subtypes.

Biosphere

The biosphere is a set of parts of the earth's shells (litho-, hydro- and atmosphere), which is inhabited 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 inhabited 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 over 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), systems of connections that exchange matter and energy between them. On land, they are separated mainly by geographical latitude, altitude and differences in precipitation. Terrestrial ecosystems located in the Arctic or Antarctic, at high altitudes or in extremely dry areas, are relatively poor in plants and animals; species diversity peaks in the equatorial rainforests.

Earth's magnetic field

The Earth's magnetic field in the first approximation is a dipole, the poles of which are located near the geographic poles of the planet. The field forms a magnetosphere that deflects solar wind particles. They accumulate in radiation belts - two concentric torus-shaped regions around the Earth. Near the magnetic poles, these particles can “fall out” 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 creates a magnetic field around the Earth. Convection motions 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 inversion occurred approximately 700,000 years ago.

Magnetosphere - a region of space around the Earth, which is formed when the stream of charged particles of the solar wind 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 the Earth. On the night side of the planet, the magnetosphere stretches out into 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 near the magnetic poles.

Orbit and rotation of the Earth

It takes the Earth an average of 23 hours 56 minutes and 4.091 seconds (a sidereal day) to complete one revolution around its axis. The rotation of the planet from west to east is approximately 15 degrees per hour (1 degree per 4 minutes, 15′ per minute). This is equivalent to the angular diameter of the Sun or Moon every two minutes (the apparent sizes of the Sun and Moon are about 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 reference ones by 0.001 s), the rotation axis 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 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 86164.098903691 seconds according to UT1 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 with an average speed of 29.765 km/sec. The speed ranges from 30.27 km/s (at perihelion) to 29.27 km/s (at aphelion). Moving in orbit, the Earth makes a complete revolution in 365.2564 mean 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 speed of the Earth's orbit is not constant: in July (during the passage of aphelion) it is minimal and is 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 Milky Way galaxy in an almost circular orbit at a speed of about 220 km/s. In turn, the solar system as part of the Milky Way moves at a speed of about 20 km/s towards a point (apex) located on the border of the constellations Lyra and Hercules, accelerating as the universe expands.

The Moon revolves with the Earth 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. Seen from the north celestial pole, the moon moves around the earth in a counterclockwise direction. In the same direction, the circulation of all the planets around the Sun, and the rotation of the Sun, Earth and Moon around their axis. The axis of rotation of the Earth is deflected from the 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 season); the Moon's orbit is tilted 5 degrees relative to the Earth's orbit (without this tilt, 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 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 the North Pole deviates away from the Sun, everything is reversed 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 half a year at the North Pole.

These changes in climate (due to the tilt of the earth's axis) cause the seasons to change. The four seasons are determined by the solstices - the moments when the earth's axis is maximally tilted towards the Sun or away from the Sun - and the equinoxes. The winter solstice occurs around December 21st, the summer solstice around June 21st, the spring equinox around March 20th, and the autumn equinox around September 23rd. 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 named the same, that is, for example, February in the northern hemisphere is the last (and coldest) month of winter, and in the southern hemisphere - the last (and warmest ) month of summer).

The tilt angle of the earth's axis is relatively constant for a long time. However, it undergoes minor shifts (known as nutation) at intervals of 18.6 years. There are also long-term fluctuations (about 41,000 years) known as Milankovitch cycles. The orientation of the Earth's axis also changes with time, the duration of the precession period is 25,000 years; this precession is the cause of the difference between the sidereal year and the tropical year. Both of these motions are caused by the changing attraction exerted by the Sun and Moon on the Earth's equatorial bulge. The poles of the Earth move relative to its surface by several meters. This movement of the poles has a variety of cyclical components, which together are called quasi-periodic motion. 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 rotation of the Earth is also not constant, which is reflected in the change in the length of the day.

The Earth is currently going through perihelion around January 3rd and aphelion around July 4th. The amount of solar energy reaching the Earth at perihelion is 6.9% more than at aphelion, since the distance from the Earth to the Sun at aphelion is 3.4% greater. This is due to the inverse square law. Since the southern hemisphere is tilted towards the sun at about the same time that the Earth is closest to the sun, it receives slightly more solar energy during 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 (the sphere of influence of the earth's gravity) is approximately 1.5 million km. This is the maximum distance at which the influence of the Earth's gravity is greater than the influence of the gravitations of other planets and the Sun.

Observation

The Earth was first photographed from space in 1959 by the 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 Earth rising from lunar orbit. In 1972, the crew of Apollo 17 took the famous picture of the Earth - "The Blue Marble".

From outer space and from the "outer" planets (located beyond the orbit of the Earth), one can observe the passage of the Earth through phases similar to those of the moon, just as an earthly observer 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, in relation to the size of its planet, satellite of the solar system. After 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 revolution of the Moon 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 revolution of the Moon around the Earth, the Sun illuminates various parts of the satellite's surface, which is manifested in the phenomenon of lunar phases: the dark part of the surface is separated from the light by a terminator.

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

The moon can significantly affect 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 tidal synchronization of the Earth with the Moon. If the Earth's axis of rotation approached the plane of the ecliptic, then as a result the climate on the planet would become extremely severe. One of the poles would point directly at the Sun, and the other would point in the opposite direction, and as the Earth revolves around the Sun, they would change places. The poles would point directly at the Sun in summer and winter. Planetologists who have studied this situation argue that in this case, all large animals and higher plants would have died 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, 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 as a result of the collision of the protoplanet Thei (roughly the size of Mars) with the 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, however, there are at least two natural co-orbital satellites - asteroids 3753 Cruitney, 2002 AA29 and many artificial ones.

Asteroids approaching the Earth

The fall of large (several thousand km in diameter) asteroids to the Earth poses a danger of its destruction, however, all similar bodies observed in the modern era are too small for this, and their fall is dangerous only for the biosphere. According to popular hypotheses, such falls could cause several mass extinctions. Asteroids with perihelion distances less than or equal to 1.3 astronomical units that may within the foreseeable future approach Earth by less than or equal to 0.05 AU. i.e., 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 fall to the planet is regarded as negligible. According to modern estimates, collisions with such bodies (according to the most pessimistic forecasts) are unlikely to occur more often than once every hundred thousand years.

Geographic 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

Use of sushi

Data for 2011

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

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

Socio-economic geography

On October 31, 2011, the world's population reached 7 billion people. According to UN estimates, 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, it varies greatly in different parts of the Earth, and it is highest in Asia. According to forecasts, by 2030 the level of urbanization of the population will reach 60%, while now it is 49% on average in the world.

Role in culture

The Russian word "land" goes back to Praslav. *zemja with the same meaning, which, in turn, continues the Proto-I.e. *dheĝhōm "earth".

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

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

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

The Aztecs called the Earth Tonantzin - "our mother". Among 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, so, 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; This view was held by Pythagoras. In the Middle Ages, most Europeans believed that the Earth was spherical, as witnessed 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 signs 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 the beginning of space flights, the Earth was often depicted as a green world. Fantast Frank Paul may have been the first to depict a cloudless blue planet (with clearly defined land) on the back of the July issue of Amazing Stories in 1940.

In 1972, the crew of Apollo 17 took the famous photograph of the Earth, called "Blue Marble" (Blue Marble). An image of 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 (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

In the last two centuries, a growing environmental movement has been concerned about the growing impact of human activities on the nature of the Earth. The key tasks of this socio-political movement are the protection of natural resources, the elimination of pollution. Conservationists advocate sustainable use of the planet's resources and environmental management. This, in their opinion, can be achieved by making changes in public policy and changing the individual attitude of each person. This is especially true for the large-scale use of non-renewable resources. The need to take into account the impact of production on the environment imposes additional costs, which leads to 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 core of the Sun, the luminosity of the star 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 orbit. According to some climate models, an increase in the amount of solar radiation falling on the Earth's surface will lead to catastrophic consequences, including the possibility of the complete evaporation of all oceans.

An increase in the temperature of the Earth's surface will accelerate the inorganic circulation of CO2, reducing its concentration to a lethal level for plants (10 ppm for C4 photosynthesis) in 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 become impossible in a few million years. In another billion years, water from the surface of the planet will completely disappear, and the average surface temperature will reach 70 ° C. Most of the land will become unsuitable for the existence of life, and it must first of all remain in the ocean. But even if the Sun were eternal and unchanging, then the continued internal cooling of the Earth could lead to the loss of most of the atmosphere and oceans (due to reduced volcanic activity). By that time, the only living creatures on Earth will be extremophiles, organisms that can withstand high temperatures and lack of water.

After 3.5 billion years from now, the luminosity of the Sun will increase by 40% compared to the current level. Conditions on the Earth's surface by that time will be similar to the surface conditions of modern Venus: the oceans will completely evaporate and evaporate into space, the surface will become a barren hot desert. This catastrophe will make it impossible for any life forms to exist on Earth. In 7.05 billion years, the solar core will run out of hydrogen. This will cause the Sun to exit the main sequence and enter the red giant stage. The model shows that it will increase in radius to a value equal to about 77.5% of the current radius of the Earth's orbit (0.775 AU), and its luminosity will increase by 2350-2700 times. However, by that time, the Earth's orbit may increase to 1.4 AU. That is, because 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, studies in 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 reach 1370°C. Earth's atmosphere is likely to be blown into outer space by the strongest solar wind emitted by a red giant. After 10 million years from the time the Sun enters the red giant phase, the temperature in the solar core will reach 100 million K, a helium flash will occur, and a thermonuclear reaction will begin to synthesize carbon and oxygen from helium, the Sun will decrease in a radius of up to 9.5 modern. The stage of "burning helium" (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 reached the asymptotic giant branch, the Sun will increase in diameter by 213 times. After 20 million years, a period of unstable pulsations of the surface of the star will begin. This phase of the existence of the Sun will be accompanied by powerful flares, at times its luminosity will exceed the current level by 5000 times. This will come from the fact that previously unaffected helium residues will enter into a thermonuclear reaction.

After about 75,000 years (according to other sources - 400,000), the Sun will shed its shells, and eventually only its small central core will remain from the red giant - a white dwarf, a small, hot, but very dense object, with a mass of about 54.1% from the original solar. If the Earth can avoid absorption by the outer shells of the Sun during the red giant phase, then it will exist for many more billions (and even trillions) of years, as long as the Universe exists, but the conditions for the re-emergence of life (at least in its current form) will not be on Earth. With the entry of the Sun into the phase of a white dwarf, the surface of the Earth will gradually cool down and plunge into darkness. If we imagine the size of the Sun from the surface of the Earth of the future, then it will look not like a disk, but like a shining point with an angular size of about 0°0’9″.

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

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» Reports for elementary grades » Earth

Earth is the third from the Sun and the fifth largest planet in the solar system. The uniqueness of our planet lies in the fact that only on it more than 3 billion years ago life was born that still exists. Animals, plants, people are only here on planet Earth.

The earth is surrounded by a layer of air, which we call the atmosphere. Airless space, or space, begins where the atmosphere ends. If it did not exist on Earth, then life would be impossible. The air shell affects the climate of the planet: it protects it from the heat of the sun and the cold of space.

Water is another factor without which life on Earth would not be possible. Most of the world is covered with water.

• Distance from the Sun: 150,000,000 kilometers
• Day length: 24 hours (terrestrial)
• Length of a year: 365 days (Earth)
• 0 rings, 1 satellite

Origins of astronomy

Concepts, methods and laws

Planets and their fragments

Stars

The sun

constellations

galaxies

telescopes

observatories

Spaceports and space exploration

Personalities

Planet Earth

Secrets of space and our planet

Video

It is interesting…

A car traveling at an average speed of 60 miles per hour would take approximately 48 million years to reach our nearest star (after the Sun), Proxima Centauri.

Question: A report on how the planet Earth appeared. Grade 5, please.

How did the planets in our solar system form?

Nowadays, the solar system and the planets surrounding it have been studied quite well. However, scientists still do not have a clear answer to the question of its origin. So, for example, back in 1755, the German astronomer and philosopher Immanuel Kant assumed that the planets of our system were formed from the same cloud of gas and dust as the Sun itself.

How planets appear

The Soviet scientist Otto Schmidt believed that the material for the formation of planets at the initial stage was "captured" by the Sun from space.

There is also a theory that the substance for building the planetary system was separated from the Sun itself as a result of an explosion.

Which of these is true, we most likely will never know, so choose for yourself what you like best, it is even possible that the biblical tale of the birth of the solar system may turn out to be true.

Abstract on the topic

"Earth is a planet in the solar system"

Two groups of planets

Terrestrial planets. Earth-Moon system

Earth

Ancient and modern explorations of the Earth

Exploring the Earth from space

Origin of life on earth

Earth's only satellite is the Moon

Conclusion

The structure and composition of the solar system.

two groups of planets.

Our Earth is one of the 8 major planets revolving around the Sun. It is in the Sun that the main part of the matter of the solar system is concentrated. The mass of the Sun is 750 times the mass of all the planets and 330,000 times the mass of the Earth.

Under the influence of the force of its attraction, the planets and all other bodies of the solar system move around the sun.

The distances between the Sun and the planets are many times greater than their size, and it is almost impossible to draw such a diagram that would observe a single scale for the Sun, planets and the distances between them. The diameter of the Sun is 109 times larger than the Earth, and the distance between them is about the same number of times the diameter of the Sun.

In addition, the distance from the Sun to the last planet of the solar system (Neptune) is 30 times greater than the distance to the Earth. If we depict our planet as a circle with a diameter of 1 mm, then the Sun will be at a distance of about 11 m from the Earth, and its diameter will be about 11 cm. The orbit of Neptune will be shown as a circle with a radius of 330 m.

Therefore, they usually cite not a modern diagram of the solar system, but only a drawing from Copernicus's book "On the Revolution of the Celestial Circles" with other, very approximate proportions.

According to physical characteristics, large planets are divided into two groups.

One of them - the planets of the terrestrial group - is the Earth and similar Mercury, Venus and Mars. The second includes the giant planets: Jupiter, Saturn, Uranus and Neptune. Until 2006, Pluto was considered the largest planet farthest from the Sun. Now, together with other objects of similar size - long-known large asteroids (see § 4) and objects discovered on the outskirts of the solar system - it is among the dwarf planets.

The division of the planets into groups can be traced by three characteristics (mass, pressure, rotation), but most clearly by density.

Planets belonging to the same group differ insignificantly in density, while the average density of terrestrial planets is about 5 times greater than the average density of giant planets (see Fig.

Most of the mass of the terrestrial planets is in solid matter. The Earth and other planets of the terrestrial group consist of oxides and other compounds of heavy chemical elements: iron, magnesium, aluminum and other metals, as well as silicon and other non-metals.

The four most abundant elements in the solid shell of our planet (lithosphere) - iron, oxygen, silicon and magnesium - account for over 90% of its mass.

The low density of the giant planets (for Saturn it is less than the density of water) is explained by the fact that they consist mainly of hydrogen and helium, which are predominantly in gaseous and liquid states. The atmospheres of these planets also contain hydrogen compounds - methane and ammonia.

Differences between the planets of the two groups arose already at the stage of their formation (see § 5).

Of the giant planets, Jupiter is best studied, on which, even in a small school telescope, numerous dark and light stripes are visible, stretching parallel to the planet's equator. This is what cloud formations look like in its atmosphere, the temperature of which is only -140 ° C, and the pressure is about the same as at the surface of the Earth.

The reddish-brown color of the bands is apparently due to the fact that, in addition to the ammonia crystals that form the basis of the clouds, they contain various impurities.

The images taken by spacecraft show traces of intense and sometimes persistent atmospheric processes. So, for over 350 years, an atmospheric vortex, called the Great Red Spot, has been observed on Jupiter. In the earth's atmosphere, cyclones and anticyclones exist on average for about a week. Atmospheric currents and clouds have been recorded by spacecraft on other giant planets, although they are less developed than on Jupiter.

Structure. It is assumed that as it approaches the center of the giant planets, due to an increase in pressure, hydrogen should pass from a gaseous to a gaseous state, in which its gaseous and liquid phases coexist.

At the center of Jupiter, the pressure is millions of times higher than the atmospheric pressure that exists on Earth, and hydrogen acquires the properties characteristic of metals.

In the depths of Jupiter, metallic hydrogen, together with silicates and metals, forms a core, which is approximately 1.5 times larger in size and 10–15 times larger in mass than the Earth.

Weight. Any of the giant planets exceeds in mass all the terrestrial planets combined. The largest planet in the solar system - Jupiter is larger than the largest planet of the terrestrial group - the Earth by 11 times in diameter and more than 300 times in mass.

Rotation.

The differences between the planets of the two groups are also manifested in the fact that the giant planets rotate faster around the axis, and in the number of satellites: there are only 3 satellites for 4 terrestrial planets, more than 120 for 4 giant planets.

All these satellites consist of the same substances as the terrestrial planets - silicates, oxides and sulfides of metals, etc., as well as water (or water-ammonia) ice. In addition to numerous craters of meteorite origin, tectonic faults and cracks in their crust or ice cover have been found on the surface of many satellites. The discovery of about a dozen active volcanoes on the closest satellite to Jupiter, Io, turned out to be the most surprising.

This is the first reliable observation of terrestrial-type volcanic activity outside our planet.

In addition to satellites, giant planets also have rings, which are clusters of small bodies.

They are so small that they cannot be seen individually. Due to their circulation around the planet, the rings appear to be continuous, although both the surface of the planet and the stars shine through the rings of Saturn, for example. The rings are located in close proximity to the planet, where large satellites cannot exist.

Terrestrial planets. Earth-Moon system

Due to the presence of a satellite, the Moon, the Earth is often called a double planet. This emphasizes both the commonality of their origin and the rare ratio of the masses of the planet and its satellite: the Moon is only 81 times smaller than the Earth.

Sufficiently detailed information will be given about the nature of the Earth in subsequent chapters of the textbook.

Therefore, here we will talk about the rest of the planets of the terrestrial group, comparing them with ours, and about the Moon, which, although it is only a satellite of the Earth, by its nature belongs to planetary-type bodies.

Despite the common origin, the nature of the moon is significantly different from the earth, which is determined by its mass and size. Due to the fact that the force of gravity on the surface of the Moon is 6 times less than on the surface of the Earth, it is much easier for gas molecules to leave the Moon.

Therefore, our natural satellite is devoid of a noticeable atmosphere and hydrosphere.

The absence of an atmosphere and slow rotation around the axis (a day on the Moon is equal to an Earth month) lead to the fact that during the day the surface of the Moon heats up to 120 ° C, and cools down to -170 ° C at night.

Due to the absence of an atmosphere, the lunar surface is subject to constant “bombardment” by meteorites and smaller micrometeorites that fall on it at cosmic speeds (tens of kilometers per second). As a result, the entire Moon is covered with a layer of finely divided substance - regolith. As the American astronauts who have been on the Moon describe, and as the photographs of the traces of lunar rovers show, in terms of their physical and mechanical properties (particle sizes, strength, etc.)

n.) regolith is similar to wet sand.

When large bodies fall on the surface of the Moon, craters up to 200 km in diameter are formed. Craters meter and even centimeter in diameter are clearly visible in the panoramas of the lunar surface obtained from spacecraft.

Under laboratory conditions, samples of rocks delivered by our automatic stations "Luna" and American astronauts who visited the Moon on the Apollo spacecraft were studied in detail.

This made it possible to obtain more complete information than in the analysis of the rocks of Mars and Venus, which was carried out directly on the surface of these planets. Lunar rocks are similar in composition to terrestrial rocks such as basalts, norites, and anorthosites. The set of minerals in lunar rocks is poorer than in terrestrial, but richer than in meteorites. Our satellite does not have and never had a hydrosphere or an atmosphere of the same composition as on Earth.

Therefore, there are no minerals that can be formed in the aquatic environment and in the presence of free oxygen. Lunar rocks are depleted in volatile elements compared to terrestrial ones, but they are distinguished by an increased content of iron and aluminum oxides, and in some cases titanium, potassium, rare earth elements and phosphorus. No signs of life, even in the form of microorganisms or organic compounds, have been found on the Moon.

The light areas of the Moon - the "continents" and the darker ones - the "seas" differ not only in appearance, but also in relief, geological history and the chemical composition of the substance covering them.

On the younger surface of the "seas", covered with solidified lava, there are fewer craters than on the older surface of the "continents". In various parts of the Moon, such relief forms as cracks are noticeable, along which the crust is shifted vertically and horizontally. In this case, only fault-type mountains are formed, and there are no folded mountains, so typical for our planet, on the Moon.

The absence of erosion and weathering processes on the Moon allows us to consider it a kind of geological reserve, where all the landforms that have arisen during this time have been preserved for millions and billions of years.

Thus, the study of the Moon makes it possible to understand the geological processes that took place on Earth in the distant past, of which no traces remain on our planet.

3. Earth.

Earth is the third planet from the Sun in the solar system. It orbits the star at an average distance of 149.6 million km.

km over a period of 365.24 days.

The Earth has a satellite, the Moon, which revolves around the Sun at an average distance of 384,400 km. The inclination of the earth's axis to the plane of the ecliptic is 66033'22".

The period of rotation of the planet around its axis is 23 hours 56 minutes 4.1 seconds. Rotation around its axis causes the change of day and night, and the tilt of the axis and circulation around the Sun - the change of seasons. The shape of the Earth is a geoid, approximately a triaxial ellipsoid, a spheroid. The average radius of the Earth is 6371.032 km, equatorial - 6378.16 km, polar - 6356.777 km.

The surface area of ​​the globe is 510 million km², the volume is 1.083 * 1012 km², the average density is 5518 kg / m³. The mass of the Earth is 5976 * 1021 kg.

The earth has magnetic and electric fields. The gravitational field of the Earth determines its spherical shape and the existence of the atmosphere.

According to modern cosmogonic concepts, the Earth was formed about 4.7 billion years ago from the gaseous matter scattered in the protosolar system. As a result of the differentiation of matter, the Earth, under the influence of its gravitational field, under the conditions of heating of the earth's interior, arose and developed different in chemical composition, state of aggregation and physical properties of the shell - the geosphere: core (in the center), mantle, earth's crust, hydrosphere, atmosphere, magnetosphere.

The composition of the Earth is dominated by iron (34.6%), oxygen (29.5%), silicon (15.2%), magnesium (12.7%). The earth's crust, mantle and inner part of the core are solid (the outer part of the core is considered liquid).

From the surface of the Earth to the center, pressure, density and temperature increase.

The pressure in the center of the planet is 3.6 * 1011 Pa, the density is about 12.5 * 103 kg / m³, the temperature ranges from 50000ºС to 60000ºС.

The main types of the earth's crust are continental and oceanic; in the transition zone from the mainland to the ocean, a crust of intermediate structure is developed.

Most of the Earth is occupied by the World Ocean (361.1 million km²; 70.8%), the land is 149.1 million km² (29.2%), and forms six continents and islands. It rises above the world ocean level by an average of 875 m (the highest height is 8848 m - Mount Chomolungma), mountains occupy more than 1/3 of the land surface.

Report: Earth as a planet of the solar system

Deserts cover about 20% of the land surface, forests - about 30%, glaciers - over 10%. The average depth of the world ocean is about 3800 m (the greatest depth is 11020 m - the Mariana Trench (trough) in the Pacific Ocean). The volume of water on the planet is 1370 million km³, the average salinity is 35 g/l. The atmosphere of the Earth, the total mass of which is 5.15 * 1015 tons, consists of air - a mixture of mainly nitrogen (78.08%) and oxygen (20.95%), the rest is water vapor, carbon dioxide, as well as inert and other gases.

The maximum land surface temperature is 570º-580º C (in the tropical deserts of Africa and North America), the minimum is about -900º C (in the central regions of Antarctica). The formation of the Earth and the initial stage of its development belong to pregeological history.

The absolute age of the most ancient rocks is over 3.5 billion years. The geological history of the Earth is divided into two unequal stages: the Precambrian, which occupies approximately 5/6 of the entire geological chronology (about 3 billion years) and the Phanerozoic, covering the last 570 million years.

About 3-3.5 billion years ago, as a result of the natural evolution of matter, life arose on Earth, and the development of the biosphere began.

The totality of all living organisms inhabiting it, the so-called living matter of the Earth, had a significant impact on the development of the atmosphere, hydrosphere and sedimentary shell.

A new factor that has a powerful influence on the biosphere is the production activity of man, who appeared on Earth less than 3 million years ago. The high growth rate of the Earth's population (275 million people in 1000, 1.6 billion people in 1900 and about 6.3 billion people in 1995) and the increasing influence of human society on the natural environment have put forward the problems of rational use of all natural resources and nature protection.

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Earth in the solar system

Our planet Earth is the third planet from the Sun in the solar system.

She enters earthlygroup of planets(four planets of the solar system: Mercury, Venus, Earth, Mars). They are also called inner planets. The Earth is the largest planet among the terrestrial group of planets in terms of diameter, mass and density.

Earth is called the Blue Planet.

It is indeed blue, as in a picture taken from space, but the main thing is that it is the only currently known planet in the solar system inhabited by living organisms.

The mass of the Earth is 5.9736 1024 kg, its surface area is 510,072,000 km², and its average radius is 6,371.0 km.

Scientists have determined the age of the Earth - about 4.54 billion years.

So, in general, she is already an old woman ... And her origin is from the solar nebula. She wandered the sky alone for a short time: she soon acquired a satellite for herself - the Moon, this is her only natural satellite.

Scientists say that life appeared on Earth about 3.5 billion years ago.

But we will talk about this in more detail in the section of our website "Planet Earth", where we will consider various hypotheses about the origin of life on Earth.

With the advent of life, the Earth's atmosphere changed significantly, began to form ozonelayer, which, together with the Earth's magnetic field, weakens harmful solar radiation and preserves the conditions of life on the planet.

What is the "ozone layer"?

This is a part of the stratosphere at an altitude of 12 to 50 km, in which, under the influence of ultraviolet radiation from the Sun, molecular oxygen (O2) dissociates into atoms, which then combine with other O2 molecules, forming ozone(O3).

The outer shell of the earth (geosphere) is called the earth's crust. So, the Earth's crust is divided into several segments, or tectonic plates(relative to integral blocks), which are in constant motion relative to each other, which explains the occurrence of earthquakes, volcanoes and mountain formation processes.

Approximately 70.8% of the surface of the planet Earth is World Ocean- the water shell of the Earth, surrounding the continents and islands and characterized by a common salt composition.

The rest of the surface is occupied by continents (continents) and islands.

Liquid water, known to us by the formula H2O, does not exist on the surfaces of other planets in the solar system. But it is necessary for life in any form. In a solid state, water is called ice, snow or hoarfrost, and in a gaseous state - water vapor - in this state it is found on other celestial bodies, but in liquid form - only on Earth. About 71% of the Earth's surface is covered with water (oceans, seas, lakes, rivers, ice).

Earth's interior is quite active and consists of a thick, highly viscous layer called the mantle.

Mantle- this is the part of the Earth (geosphere), located directly under the crust and above the core. The mantle contains most of the Earth's matter. The mantle is also found on other planets. The mantle covers the liquid outer core (which is the source of the Earth's magnetic field) and the inner solid core, presumably iron.

The Earth in space interacts (attracts) with other objects, including the Sun and the Moon.

The Earth revolves around the Sun in 365.26 days. The Earth's axis of rotation is tilted 23.4° relative to its orbital plane, which causes seasonal changes on the planet's surface with a period of one tropical year (365.24 solar days). Tropicalyear is the length of time during which the Sun completes one cycle of the seasons.

Day are approximately 24 hours

The composition of the Earth's atmosphere includes 78.08% nitrogen (N2), 20.95% oxygen (O2), 0.93% argon, 0.038% carbon dioxide, about 1% water vapor (depending on climate).

Relating to the terrestrial planets, the Earth has a solid surface.

Earth is a unique planet!

The largest of the four terrestrial planets in the solar system in both size and mass, the Earth has the highest density, the strongest surface gravity (gravity), and the strongest magnetic field of the four planets, generated by intraterrestrial sources.

earth shape

The shape of the Earth is an oblate ellipsoid.

The highest point on the solid surface of the Earth is a mountain Everest, or, translated from Tibetan, Chomolungma which is located in the Himalayas.

Its height is 8848 m above sea level. And the lowest point Mariana Trench, which is located in the west of the Pacific Ocean, next to the Mariana Islands. Its depth is 11,022 m below sea level. Let's talk a little about her.

The British were the first to explore the Mariana Trench. They converted the military three-masted Challenger corvette with sailing equipment into an oceanographic vessel for hydrological, geological, chemical, biological and meteorological work.

This was done back in 1872. But the first data on the depth of the Mariana Trench, or, as it is sometimes called, the Mariana Trench, were obtained only in 1951: they measured the depression and determined its depth at 10,863 m. (Challenger Deep). Imagine that in the depths of the Mariana Trench, the highest mountain of our planet, Everest, can easily fit, and above it there will still be more than a kilometer of water to the surface ... Of course, we are not talking about the area, but only about the depth.

Then the Mariana Trench was explored by Soviet scientists on the Vityaz research vessel, and in 1957 they declared the maximum depth of the trench equal to 11,022 meters, but the most striking thing is that they refuted the opinion prevailing at that time about the impossibility of life at a depth of more than 6000-7000 meters - life in the Mariana Trench exists!

And on January 23, 1960, the first and only dive of a man to the bottom of the Mariana Trench took place.

The only people to have been "at the bottom of the Earth" were US Navy Lieutenant Don Walsh and explorer Jacques Picard. They dived on the Trieste bathyscaphe. At the bottom, the researchers were only 12 minutes, but that was enough for them to make a sensational discovery about the presence of life at such a depth - they saw flat fish there, similar to flounder, up to 30 cm in size.

But the researchers of the trench were repeatedly frightened by unknown phenomena in the depths, so the mystery of the Mariana Trench has not yet been fully disclosed.

The chemical composition of the Earth

The earth consists mainly of iron (32.1%), oxygen (30.1%), silicon (15.1%), magnesium (13.9%), sulfur (2.9%), nickel (1.8 %), calcium (1.5%) and aluminum (1.4%); the remaining elements account for 1.2%.

It is assumed that the internal space consists of iron (88.8%), a small amount of nickel (5.8%), sulfur (4.5%).

Geochemist Frank Clark calculated that the earth's crust is just over 47% oxygen. The most common rock-constituting minerals of the earth's crust are almost entirely composed of oxides.

The internal structure of the Earth

Like all planets of the terrestrial group, it has a layered structure.

You can see the composition on the diagram. Let's take a closer look at each part.

Earth's crust is the upper part of solid ground. There are two types of crust: continental and oceanic.

The thickness of the crust ranges from 6 km under the ocean to 30-50 km on the continents. Three geological layers are distinguished near the continental crust: sedimentary cover, granite and basalt. Under the earth's crust is mantle- the shell of the Earth, composed mainly of rocks consisting of silicates of magnesium, iron, calcium, etc.

The mantle makes up 67% of the total mass of the Earth and about 83% of the total volume of the Earth. It extends from depths of 5-70 kilometers below the boundary with the earth's crust to the boundary with the core at a depth of 2900 km. Above the border of 660 kilometers is upper mantle, and lower - lower. These two parts of the mantle have different composition and physical properties. Although information about the composition of the lower mantle is limited.

Core- the central, deep part of the Earth, the geosphere, located under the mantle and consisting of an iron-nickel alloy with an admixture of other elements.

But these figures are speculative. Depth - 2900 km. The core of the Earth is divided into a solid inner core with a radius of about 1300 km and a liquid outer core with a radius of about 2200 km, between which a transition zone is sometimes distinguished. The temperature in the center of the Earth's core reaches 5000°C. The mass of the core is 1.932 1024 kg.

Earth's hydrosphere

This is the totality of all the water resources of the Earth: oceans, a network of rivers, groundwater, as well as clouds and water vapor in the atmosphere.

Part of the water is in a solid state (cryosphere): glaciers, snow cover, permafrost.

Earth's atmosphere

This is the name of the gaseous envelope around the Earth. The atmosphere is divided into troposphere(8-18 km), tropopause(transitional layer from the troposphere to the stratosphere, in which the decrease in temperature with height stops), stratosphere(at an altitude of 11-50 km), stratopause(about 0 °C), mesosphere(from 50 to 90 km), mesopause(about -90 °C), Karman line(height above sea level, which is conventionally accepted as the boundary between the Earth's atmosphere and space, about 100 km above sea level), boundary of the earth's atmosphere(about 118 km), thermosphere(upper limit about 800 km), thermopause(area of ​​the atmosphere adjacent to the top of the thermosphere), exosphere(scattering sphere, above 700 km).

The gas in the exosphere is highly rarefied, and hence its particles leak into interplanetary space.

Biosphere of the Earth

This is a set of parts of the earth's shells (litho-, hydro- and atmosphere), which is inhabited by living organisms, is under their influence and is occupied by the products of their vital activity.

Earth's magnetic field

The Earth's magnetic field, or geomagnetic field, is a magnetic field generated by intraterrestrial sources.

Earth rotation

It takes the Earth 23 hours 56 minutes and 4.091 seconds to complete one revolution around its axis.

The rotation of the Earth is unstable: the speed of its rotation changes, the geographic poles move, the axis of rotation fluctuates. In general, the movement is slowing down. It is calculated that the duration of one revolution of the Earth has increased over the past 2000 years by an average of 0.0023 seconds per century.

Around the Sun, the Earth moves in an elliptical orbit at a distance of about 150 million km with an average speed of 29.765 km/sec.

Geographic information about the Earth

Square

• Surface: 510.073 million km²
• Land: 148.94 million km²
• Water: 361.132 million km²
• 70.8% of the planet's surface is covered with water and 29.2% is land.

coastline length 286,800 km

For the first time…

The Earth was first photographed from space in 1959 by the 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 Earth rising from lunar orbit. In 1972, the crew of Apollo 17 took the famous picture of the Earth - "The Blue Marble" - "Blue marble ball".

Planet Earth, the third planet in terms of distance from the Sun, it is the largest in terms of mass among other Earth-like planets in the solar system. The uniqueness of the Earth lies in the fact that it is the only planet known today on which life exists.

Science says that the planet Earth was formed 4.5 billion years ago, and soon after its formation, with its gravitational field, it attracted the only satellite for today - the Moon.

It is believed that life on earth arose about 3.5 billion years ago, i.e.

1 billion years after the formation of the earth. The possibility of the formation of life on Earth is due to the fact that after its formation and up to the present day, the planet's biosphere has changed its various abiotic factors, as well as the atmosphere itself, this has led to the emergence and formation of the Earth's ozone ball, as well as the emergence and continuous growth of anaerobic organisms, which, in cooperation with harmful radiation was blocked by a magnetic field.

All these factors, and especially the blocking of external cosmic radiation, made it possible for life to develop at a continuous pace, allowing it to evolve.

The crust of the globe is divided into several tectonic plates. Tectonic plates tend to change their location and constantly move (migrate), but their movement is measured in millions of years.

About 70% of the entire earth's surface is sea water, the rest of the space (about 30%) is continents and islands.

Liquid water is essential for the existence of all life forms on Earth, but today water in this state can only be found on Earth and on no other planet. Water also exists on other planets of the solar system, but in a solid state, this, as well as a number of other factors, does not allow life to develop on these planets.

Planet Earth, like other cosmic bodies in the solar system and throughout the universe, interacts with other cosmic objects - the Sun and the Moon.

The Earth revolves around the Sun, and it makes a complete revolution around the Sun in 365.26 Earth days. This period of time is called the sidereal year.

A sidereal year is equal to 365.26 solar days on earth.

The Earth is constantly rotating, and its axis of rotation is tilted by 24.3 degrees relative to its orbital plane.

A report on how the planet Earth appeared Grade 5 please.

The only and constant satellite of the Earth is the Moon. Scientists believe that the Moon was attached to the Earth and began its rotation around it about 4.53 billion years ago. The moon has its own specific functions and has a considerable influence on life on Earth.

In addition, early cosmic bombardment by comets played a certain role in the formation of the Earth, namely in the formation of the oceans on the planet. Such bombardments in the early stages of formation played a very significant role, and those asteroids that fell to Earth after the formation of the oceans had a strong impact on the formation of the environment on the planet.

Many scientists attribute the role of "destroyers of life", since, in their opinion, it is asteroids that are responsible for the extinction of several species of living beings before the appearance of mankind.

In shape, our planet is very similar to an ellipsoid, and not to a round one, as it was depicted a little earlier.

To be precise, the planet Earth has a spherical shape, which is thickened at the equator. The diameter of the planet is almost 12,750 km.

The chemical composition that the planet possesses consists mainly of iron (32.1%), aluminum (1.5%), nickel (1.8%), calcium (1.5%), magnesium (13.9%), sulfur (2.9%), silicon (about 15%), as well as from oxygen (30.1%).

All other elements on earth account for about 1-1.2%.

The internal structure of the Earth is usually distinguished into:

- the atmosphere;

- the biosphere;

- hydrosphere;

- lithosphere;

- pyrosphere;

- centrosphere

Which are also divided into several components.

The atmosphere of the Earth is the outer gaseous shell of the planet, the lower boundary of which runs through the hydrosphere and lithosphere, and the upper line of the atmosphere is at an altitude of 1000 kilometers from the surface.

In the atmosphere, it is also customary to distinguish between the troposphere, which is considered the moving layer, the stratosphere, which is located above the troposphere, and the last (upper) layer - the ionosphere.

The troposphere is about 10 km, and its mass is about 3/4 of the entire mass of the atmosphere (ie, approximately 75%). A layer of the stratosphere extends to a height of about 80 km above the troposphere. Above all layers is the ionosphere. This layer got its name because it is constantly ionized by cosmic rays.

The hydrosphere occupies about 71% of the entire surface of the planet. The salinity of this layer is 35 g/l, and the temperature ranges from 3 to 32°C.

The most unique layer on our planet, the biosphere, merges with the lithosphere, hydrosphere and atmosphere. The biosphere itself is subdivided into several spheres - the sphere of plants, which have a population of about 500,000 different species, as well as the animal sphere, which has a total number of species of over 1 million.

The lithosphere is the stone shell of the planet. Its thickness varies from 40 to 100 kilometers; it makes up the bottom of the oceans, continents and islands.

Immediately below the lithosphere is the pyrosphere and is considered to be the fiery shell of the globe.

The temperature of the pyrosphere rises by about one degree every 33 meters of depth. There is a hypothesis that due to the pyrosphere, the rocks located in the depths of the Earth are in a molten state.

The Earth's centrosphere, according to many scientists, is located approximately at a depth of 1800 kilometers and consists mainly of nickel and iron. The temperature of the centrosphere reaches several thousand degrees, and the pressure is about 3 million atmospheres.

in natural history

on the topic: "The uniqueness of the planet Earth"

Completed: student 5 "d" class

Galiev Edgar

Edited by: Vasinkina Yu.V.

Zainsk 2012

geography
Fifth grade

first

solar system

A few decades ago, human flight was fantastic in space. And today, not only the beginning of a spacecraft with a crew has become a reality, but the first space tourists have appeared, and we are preparing scientific expeditions to other planets.

Who knows, maybe this textbook is reading the next participant in the flight to Mars. But even if this is not the case, the information they contain is needed by everyone. This will help you feel like a part of not only a small settlement, a city and a large country, but also an infinite universe with many galaxies, one of which belongs to our solar system.

Our star home is the solar system.

Planet Earth is part of the solar system, the center of which is the Star of the Sun. It is a huge red gas ball, consisting of hydrogen.

Thermonuclear reactions take place in the Sun, resulting in a huge amount of heat and light. The temperature in the room reaches 15 million degrees Celsius! Our planet is in an eternally cold and dark space, and the Sun provides the energy it needs.

Without sunlight and light, there would be no life on Earth.

Our planet is a bit small compared to the sun, with poppies along a big orange, for example. The sun is huge, like all the "inhabitants" of the solar system together. Its diameter is 109 times the diameter of the Earth.

The gravitational force of the Sun acts on all the bodies of the Sun system and makes them turn to their orbits.

orbit(from the Latin "orbit" - between them) - the path along which any natural or artificial celestial body moves.

The composition of the solar system includes eight planets. They are divided into terrestrial planets (Merkur, Venus, Earth, Mars) and giant planets (Jupiter, Saturn, Uranus, Neptune).

Earth group planets. All four planetary groups of planets are located near the Sun.

They are small, composed of dense rocks and slowly rotate around their axis. They have only a few satellites or not: for example, the Earth has one (Moon), Mars has two, Mercury and Venus are nothing. These planets do not have fingers.

1. Scheme of the structure of the solar system. 2. Sun. The photo was taken using special light filters. 3. mercury. 4. Venus.

Mercury is the first planet in the solar system.

In order to be closer to other planets to the Sun, he turns to the earliest possible time. A year in Merkur is one revolution of the planet around the Sun, these are 88 Earth days.

The sun radiates so strongly from this small planet that the daily surface temperature reaches 430°C.

But at night it drops to -170 ° C. Under such circumstances, the existence of living organisms is excluded. Mercury has such deep craters that sunlight never reaches the bottom. It's always very cold there.

The range is much smaller than our Earth: 20 planets like Merkur can be found in the world.

Venus- the other - from the solar planet.

It is the size of our Earth. The planet is surrounded by a strong layer of carbon dioxide. This thick shell of gas passes through the sun's rays and retains heat like a film in a greenhouse without releasing it into space. Therefore, the average temperature in the surface layer of the atmosphere of Venus is about 470 ° C.

The atmosphere is compressed on the surface of Venus with a great force, almost 100 times greater than the earth's atmosphere.

the country- the third planet from the Sun, the only one in the solar system on which the conditions are favorable for the existence of life: the presence of an atmosphere containing oxygen; the temperature necessary for the development of living organisms; Protective ozone layer in the atmosphere; liquid water, carbon.

The fourth group of the planet Earth is Mars. Its mass is 9.3 times less than the mass of the Earth. He has two companions.

The surface of Mars has a rusty hue because it contains a lot of iron oxide. The Martian landscape is like pale orange dunes in the desert, with stallions.

Severe storms often rage over the planet. They kick up so much brown dust that the sky turns red. In airless weather, it is pink.

Like us, we change the season on Mars, there is a change of day and night. The Martian year is twice as long as Earth.

The red planet, scientists say, has an atmosphere, but not as dense as Earth or Venus.

big planet. A large planet (Jupiter, Saturn, Uranus, Neptune) is located far from the Sun as a planet of the Earth group. The farthest of them is Neptune: while he revolutionizes the Sun, he will be 165 years on Earth. These planets are also called gas giants because they are almost entirely gas and are large.

For example, the radius of Neptune is around the radius of the Earth, Saturn is nine, and Jupiter is eleven. The atmosphere of the giant planets consists mainly of hydrogen and helium.

The gas giants rotate much faster than the Earth's planets on their axis. (Watch the use of the terms "rotation" and "circling.") If the Earth completes a full rotation on its axis in almost 24 hours, then Jupiter takes 10 hours, Uranus 18, and Neptune 16.

Another feature of the planets of this group is the presence of many satellites.

For example, Jupiter has 60 scientists. The attraction of this wheel is so strong that it attracts all space debris like a big vacuum cleaner: particles of stones, ice and dust that form rings.

They revolve around the planet and every gas giant. Looking through a telescope, we can clearly see Saturn's bright, glossy ring.

1. The first photographs of the surface of Mars were taken from the American automatic station Viking in 1976. 2. Jupiter. 3. Saturn. 4. Uranus. 5. Neptune.

Small bodies of the solar system.

In addition to the planets and their satellites, there are many smaller planets in the solar system - asteroids (from the Greek "asters" - stars), which means "star" in Russian.

Planet Earth

Most of them rotate the Sun and form a belt of asteroids located between the orbits of Mars and Jupiter. As astronomers suggest, these are fragments of a destroyed planet or building material for an unformed celestial body. Asteroids do not have a well-defined shape, they are stone mud, sometimes with metal.

In the solar system there are also meteorite bodies - fragments of rocks of different sizes.

Take in the Earth's atmosphere, heat up strongly as a result of friction against air and burn, making a bright gesture in the sky - these are meteors (in Greek - blue in the air). The destruction of a meteoroid that has not burned up in the atmosphere and has not reached the Earth's surface is called a meteorite.

The weight of a meteorite ranges from a few grams to several tons. One of the largest - the Tunguska meteorites at the beginning of the last century fell on the territory of our country in the center of Siberia.

The solar system also includes comets (from the Greek.

"Comet" is durable). They circulate around the Sun in very elongated orbits. The more comets the Sun, the greater the speed of its movement. It has a core composed of frozen gases or cosmic dust. As it approaches the Sun, the core of the nucleus evaporates and begins to glow, and then the "head" and "tail" become visible in "space dive".

The most famous comet is Galloya - every 76 years it approaches the Earth. In ancient times, his approach caused terrible horror in people. Today, scientists around the world are interested in this incredible astronomical phenomenon.

1. Asteroid Ida. 2. Meteor in the sky.

3. The Luzhenga meteorite, located 30 km southwest of Veliky Ustyug. 4. Halley's Comet flew over the Earth in 1985. It will next be seen in 2061.

With the help of radio telescopes, special cameras equipped with light filters, astronomers receive new information about the Sun, the planets of the solar system, asteroids and other space bodies.

Questions and tasks

1. How many planets revolve around the sun? Name them. Which planet in the solar system is the hottest? Which scientists call them the "Red Planet"?
2. Do you know what the term "fallen star" means? Have you ever seen a shooting star? What is their scientific name?
3. Write the text as many words as possible with the following concepts: a) planet, b) cosmic bodies, c) solar system. Explain what combines the words you find.
4. Read the text again, find and write the names of the nearest and most distant planets from the Sun. What groups of planets in the solar system belong to? Consider and explain, depending on what signs the planets of the solar system are divided into groups.
5. How do you think the bodies of the solar system revolve around the sun?
6. In the text, find the main differences between the planets of the Earth and the giant planets. Draw a table in a notebook and fill it in.

Features of the Earth's planets from the giant planets

Imagine that you are an astronaut and that you must fly as part of a scientific expedition to Mars. What space cap (or robot) will you have to act on the surface of the planet? Think about its shape, device and color.

Draw a notebook and prepare a story.

For the curious

• Jupiter is the first largest gas giant among the planets of the solar system. Its entire surface is a huge ocean of liquid hydrogen. It is 2.5 times larger than all other planets in the solar system, its radius is 11 times the radius of the Earth.

  It has over 60 satellites and more fingers. In Jupiter's vast atmosphere, hurricanes are angry; their speed exceeds 100 m/s.

  On the surface of Jupiter, telescopes have captured a huge red part of the size of our Earth, which is an atmospheric vortex.

• The sun is the closest star to us. The size is so large that it could have over a million planets like Earth. Light from the Sun to the Earth comes in 8 minutes. The second star closest to Earth is Proxima Centauri.
• Venus rotates on its axis, not from west to east, like most planets in the solar system, but in the opposite direction. On Venus, a day is one revolution of the planet around its axis, about 243 Earth days. It is the brightest object in the sky of the Sun and Moon. Venus is usually seen in the evening after sunset or in the morning before sunrise against the backdrop of dawn.

first

Comparative characteristics of the planets of the solar system. 2. The nearest satellites of Jupiter. 3. Chemical composition of Jupiter's atmosphere (diagram).

• Uranus is the only one of all the planets in the solar system that rotates around its axis, "lies on its side."

  Scientists believe that he "fell on his side" as a result of a collision with a large cosmic body millions of years ago. Like Venus, Uranus rotates on its axis in the opposite direction from the clock.

• The duration of one year on the planet Neptune is 164.8 Earth days, Mercury - 88 Earth days.
• Merkur is the planet closest to the Sun. Due to the smaller tilt of the axis to the plane of its orbit, there are no noticeable seasonal changes on this planet.

  Mercury has no followers.

Merkur is a small planet. Its mass is a twentieth of the mass of the Earth, and its diameter is almost 2.5 times smaller than the Earth.

For observations from Earth, the Merkur is a difficult subject, since it is only visible against the background of an evening or morning dawn that is slightly above the horizon, and in addition, the observer sees only half of his disk at that time.

The Earth is in the third order in terms of distance from the Sun. It belongs to the class of terrestrial planets and is the largest in this group. As far as we know now, the unique difference of the Earth is that it has life. It was found that age of the earth is about 4.54 billion years. It was formed from cosmic dust and gas - these were the substances left after the formation of the Sun.

In the initial period of existence, our planet was in a liquid state. But over time, the reactions slowed down, the temperature dropped, and the Earth's surface began to take on a solid form. Gradually, an atmosphere began to form. Water appeared on the surface - it entered the atmosphere in the form of ice along with asteroids and other small celestial bodies. The impact of falling comets and asteroids affected the geographic relief of the Earth, temperature and other climatic conditions on its surface.

How did the appearance of the satellite of our planet? Scientists believe that the Moon was formed as a result of a global astronomical catastrophe, when the Earth tangentially collided with a huge celestial body, not inferior in size to itself. From the fragments of this asteroid, a ring was formed around the Earth, gradually transforming into the Moon. The moon has a noticeable effect on our planet, it is the cause of the ebb and flow of the world's oceans, and even leads to a slowdown in the movement of the Earth.

After the appearance of the oceans in the atmosphere of our planet, the accumulation of oxygen began. There is still no unambiguous theory of the origin of life on earth, but it is believed that as a result of various chaotic interactions of cells with each other, more and more complexly organized cells were formed, which gave rise to the simplest multicellular creatures. Gradually, life developed, and over time, the ozone layer allowed living organisms to reach land.

The surface of the Earth is not static. The continents are in motion, and what you can see on the map now is the result of constant change. It is believed that the first supercontinent, as a result of some internal or external influences, split into parts and formed a new supercontinent Pannotia about 550 million years ago, and later Pangea, which also began to separate about 200 million years ago.

Coastal areas often have a milder climate than inland areas. For example, sea and coastal breezes can affect the climate. The surface of the Earth is warming up many times faster than the waters of the sea. In the daytime, warm air rises from the bottom to the top, while the cold air that comes from the sea takes the place of the departed warmer one. With the onset of night, the reverse process begins to occur. Due to the fact that the water in the sea cools much more slowly than the land, the breezes from the land blow on the sea.

The temperature regime is also influenced by the numerous currents of the oceans. The Atlantic Ocean is crossed diagonally by the warm current of the Gulf Stream, starting its crossing in the Gulf of Mexico and ending it already at the northwestern European coast. The sea winds that blow over the Gulf Stream towards the coast create a rather mild climate for this part of Europe, milder than on the coasts of North America located at the same latitudes. The climate is also affected by cold ocean currents. For example, the Benguela Current off the African coasts of the southwestern regions and off the western South American coasts cools the tropics, otherwise it would be much hotter there.

In the central parts of the continents, far from the softening sea influences, one can observe a harsh continental climate, which has both hot summers and cold winters.

The word "continent" has Latin roots and if we translate the word "continere" literally, we get the phrase "stick together", this word is not always applied to land, but it implies unity in structure.

The largest continent of the Earth is Eurasia. Eurasia includes Europe and Asia, these are the two parts of the world in which most of the earth's population lives.

Africa is the second largest continent of the Earth, which stretches on both sides of the equator.

South America, along with North America, are located in the western part of the Earth, and like Africa on both sides of the equator. Since these two continents are connected by the narrow Isthmus of Panama, then, in fact, this mainland should be considered one big one.

Australia is the smallest continent on Earth. It is almost 100% located in the hot zone in the southern hemisphere.

The highest continent on Earth is Antarctica. This continent is also the most severe in all biological conditions of life.

As for countries, they are classified in a variety of ways. For example, they can be classified depending on the size of the territory (the area of ​​Russia is 17 million square kilometers). Countries are also classified according to the features of the natural world and location, such as tropical European or, for example, mountainous countries. A classification takes place, taking into account the diversity and national composition of the population (Slavic, mono, Romanesque, multinational countries), taking into account the form of government and the type of political regime. Also classified according to the degree of independence. The largest countries of the world are distinguished by various criteria, most often the countries occupying the largest area are called the largest.

The largest countries in the world by area are:

1. Russian Federation - 17,075,400 sq. km.

2. Canada - 9,984,670 sq. km.

3. China - 9,596,960 sq. km.

Rarely, you can hear that China is considered the largest country on Earth. This option is also correct, because here is the largest number of people. Finally, eight countries of the world are singled out the largest in terms of their economic achievements.

These countries form the "Big Eight": Russia, Japan, Italy, Canada, Germany, France, Great Britain and the leader of the entire chain is the United States, which usually stays out of competition, because it has the highest global GDP. India is a country with the most diverse ethnic group. On the territory of India, there are more than five thousand nationalities, peoples and tribes.

At the moment, the surface of the Earth, except for Antarctica and its islands, is shared by about two hundred states.

Antarctica is the largest geographical area that does not belong to any country on the planet Earth. The international treaty states that only scientific activities can be carried out in Antarctica and the unique nature of this continent must always be preserved.

On our website you can watch from the International Space Station, as well as view it completely free of charge.

Earth is the largest terrestrial planet. 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 a pear. That is why researchers sometimes call the shape that our planet has a "potatoid" (from the English potato - potatoes). Also important are the characteristics of the Earth as a celestial body, describing its spatial position. Our planet is located 149.6 million kilometers from the Sun. For comparison, Mercury is located 2.5 times closer to the star 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 Earth's. 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 rotation of the Earth around its axis and its movement in orbit is the change of day and night, as well as the 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 - are almost entirely composed of gases (hydrogen and helium). All planets that belong to the category of terrestrial ones rotate around their axis, as well as along elliptical trajectories around the Sun. Only 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 sands, various clays and minerals, stones. The average thickness is 30 km, but in some areas its value is 40-70 km. Astronauts claim that the earth's crust is not the most amazing sight from space. In some places it is reared up by mountain ranges, 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 gives shelter to hundreds of living species. However, many more plants and animals can be found on land. If we put all living creatures that live in water on one scale, and those who live on land on the other, then the bowl will be heavier. Its weight will be 2 thousand times more. This is very surprising, because the area of ​​\u200b\u200bthe ocean 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

The characterization of the Earth as a celestial body will be incomplete without a description of its internal structure. The core of the planet consists of a hot mixture of two metals - nickel and iron. It is surrounded by a hot and viscous mass, which is similar to 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 the 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 are formed in these places.

Earth 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 5,000 trillion tons.

Although in ancient times people did not know the characteristics of the planet Earth as a celestial body, even then it was assumed that it belongs precisely to the category of planets. How did our ancestors manage to draw 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 is why these celestial bodies began to be called planets (translated from Greek, the word "planet" is translated as "wandering").

Earth is the third planet from the Sun. The largest planet of the terrestrial group in terms of density, diameter, mass. Of all the known planets, only Earth has an oxygen-containing atmosphere, a large amount of water in a liquid state of aggregation. The only planet known to man that has life.

a brief description of

The Earth is the cradle of mankind, a lot is known about this planet, but all the same, we cannot unravel all its secrets at the present level of scientific development. Our planet is quite small on the scale of the Universe, its mass is 5.9726 * 1024 kg, it has the shape of a non-ideal ball, its average radius is 6371 km, the equatorial radius is 6378.1 km, the polar radius is 6356.8 km. The circumference of the great circle at the equator is 40,075.017 km, and at the meridian 40,007.86 km. The volume of the Earth is 10.8 * 10 11 km 3.

The center of the Earth's rotation is the Sun. The movement of our planet occurs within the ecliptic. It rotates in an orbit that formed at the beginning of the formation of the solar system. The shape of the orbit is presented as a non-perfect circle, the distance from the sun in January is 2.5 million km closer than in June, is considered an average distance from the Sun of 149.5 million km (astronomical unit).

The earth rotates from west to east, but the axis of rotation and the equator are tilted with respect to the ecliptic. The Earth's axis is not vertical, it is inclined at an angle of 66 0 31' with respect to the plane of the ecliptic. The equator is tilted 23 0 with respect to the Earth's axis of rotation. The axis of rotation of the Earth does not constantly change due to precession, this change is influenced by the gravitational force of the Sun and Moon, the axis describes a cone around its neutral position, the period of precession is 26 thousand years. But besides this, the axis also experiences oscillations called nutation, since it cannot be said that only the Earth revolves around the sun, because the Earth-Moon system rotates, they are connected to each other in the form of a dumbbell, the center of gravity of which, called the barycenter, is located inside Earth at a distance from the surface of about 1700 km. Therefore, due to nutation, the fluctuations superimposed on the precession curve are 18.6 thousand years, i.e. the angle of inclination of the earth's axis is relatively constant for a long time, but undergoes minor changes with a frequency of 18.6 thousand years. The time of rotation of the Earth and the entire solar system around the center of our galaxy - the Milky Way, is 230-240 million years (galactic year).

The average density of the planet is 5.5 g / cm 3, on the surface the average density is about 2.2-2.5 g / cm 3, the density inside the Earth is high, its growth occurs abruptly, the calculation is made according to the period of free oscillations, the moment of inertia, the moment of impulse .

Most of the surface (70.8%) is occupied by the World Ocean, the rest is continents and islands.

Acceleration of free fall, at the level of the ocean at latitude 45 0: 9.81 m/s 2 .

Earth is a terrestrial planet. The terrestrial planets are characterized by high density and consist mainly of silicates and metallic iron.

The moon is the only natural satellite of the Earth, but there are also a huge number of artificial satellites in orbit.

Planet formation

The Earth was formed by the accretion of planetesimals, about 4.6 billion years ago. Planetesimals are particles that stick together in a gas and dust cloud. The process of particles sticking together is accretion. The process of contraction of these particles occurred very quickly, for the life of our Universe, several million years is considered an instant. After 17-20 million years from the beginning of formation, the Earth gained the mass of modern Mars. After 100 million years, the Earth gained 97% of its modern mass.

Initially, the Earth was molten and red-hot due to strong volcanism and frequent collisions with other celestial bodies. Gradually, the outer layer of the planet cooled and turned into the Earth's crust, which we can now observe.

It is believed that the Moon was formed in connection with the impact of a celestial body on the Earth's surface, the mass of which was about 10% of the Earth's mass, as a result of which part of the substance was ejected into near-Earth orbit. Soon, the Moon was formed from this material, at a distance of 60 thousand km. As a result of the impact, the Earth received a large momentum, which led to a period of revolution around its axis in 5 hours, as well as a noticeable tilt of the axis of rotation.

Degassing and volcanic activity created the first atmosphere on Earth. It is assumed that water, i.e. ice and water vapor were brought in by comets colliding with the Earth.

For hundreds of millions of years, the surface of the planet has been constantly changing, continents have been formed and broken up. They moved across the surface, joining together to form a continent. This process was cyclical. Approximately 750 million years ago, the supercontinent Rodinia, the earliest known, began to break up. Later, from 600 to 540 million years ago, the continents formed Pannotia and finally Pangea, which broke apart 180 million years ago.

We do not have an accurate idea of ​​the age and formation of the Earth, all these data are indirect.

The first photograph taken by Explorer-6.

Observation

The shape and internal structure of the Earth

Planet Earth has 3 different axes: along the equator, polar and equatorial radii, structurally it is a cardioid ellipsoid, it was calculated that the polar regions are slightly elevated in relation to other areas and resemble the shape of a heart, the northern hemisphere is elevated by 30 meters relative to the southern hemisphere. There is a polar asymmetry of the structure, but nevertheless we believe that the Earth has the shape of a spheroid. Thanks to the study from satellites, it was revealed that the Earth has depressions on its surface and a picture of the Earth was presented in the form of a pear, that is, it is a triaxial ellipsoid of revolution. The difference between the geoid and the triaxial ellipsoid is no more than 100 m, this is due to the uneven distribution of masses both on the surface of the Earth (oceans and continents) and inside it. At each point of the geoid surface, gravity is directed perpendicular to it, is an equipotential surface.

The main method for studying the structure of the Earth is the seismological method. The method is based on studying the change in seismic wave velocities depending on the density of matter inside the Earth.

The earth has a layered internal structure. It consists of solid silicate shells (crust and viscous mantle) and a metallic core. The outer part of the nucleus is liquid, while the inner part is solid. The structure of the planet is similar to a peach:

• thin crust - the earth's crust, the average thickness is 45 km (from 5 to 70 km), the greatest thickness is under large mountains;
• layer of the upper mantle (600 km), contains a layer that differs in physical characteristics (decrease in the speed of seismic waves), in which the substance is either heated or slightly melted - a layer called the asthenosphere (50-60 km under the oceans and 100-120 km under continents).

The part of the Earth, which is located together with the earth's crust and the upper part of the mantle, up to the asthenosphere layer, is called the Lithosphere.

1. The boundary between the upper and lower mantle (depth 660 km), the boundary every year becomes more clear and sharp, the thickness is 2 km, the wave speed and the composition of matter change on it.
2. The lower mantle reaches a depth of 2700-2900 km. existence of the middle mantle.
3. The outer core is a liquid substance (depth 4100 km), which does not transmit transverse waves, it is not necessary that this part has the form of some kind of liquid, this substance simply has the characteristics of a liquid object.
4. The inner core is a solid, iron with nickel impurities (Fe: 85.5%; Ni: 5.20%), depth 5150 - 6371 km.

All data were obtained indirectly, since no wells were drilled to such a depth, but they are theoretically proven.

The force of gravity at any point on the earth depends on Newtonian gravity, but the placement of density inhomogeneities is important, which explains the variability of gravity. There is an effect of isostasy (balancing), the higher the mountain, the larger the root of the mountain. An iceberg is a prime example of the isostasy effect. The paradox in the North Caucasus, there is no balancing, why this happens is still not known.

Earth's atmosphere

The atmosphere is the gaseous envelope surrounding the Earth. Conventionally, it borders on interplanetary space at a distance of 1300 km. Officially, it is believed that the boundary of the atmosphere is determined at an altitude of 118 km, that is, above this distance, aeronautics becomes completely impossible.

Air mass (5.1 - 5.3) * 10 18 kg. The air density near the sea surface is 1.2 kg/m 3 .

The formation of the atmosphere is caused by two factors:

• Evaporation of the matter of cosmic bodies during their fall to the Earth.
• Degassing of the earth's mantle - the release of gas during volcanic eruptions.

With the emergence of the oceans and the advent of the biosphere, the atmosphere began to change due to gas exchange with water, plants, animals and their decomposition products in soils and swamps.

The structure of the atmosphere:

1. The planetary boundary layer is the lowest layer of the planet's gaseous envelope, the properties and characteristics of which are largely determined by interaction with the type of planet's surface (liquid, solid). The layer thickness is 1-2 km.
2. The troposphere is the lower layer of the atmosphere, the most studied, at different latitudes it has different thickness values: in the polar regions 8-10 km, temperate latitudes 10-12 km, at the equator 16-18 km.
3. The tropopause is the transitional layer between the troposphere and stratosphere.
4. The stratosphere is a layer of the atmosphere located at an altitude of 11 km to 50 km. A slight change in temperature in the initial layer, followed by an increase in the layer 25-45 km from -56 to 0 0 С.
5. The stratopause is the boundary layer between the stratosphere and the mesosphere. In the stratopause layer, the temperature is kept at the level of 0 0 С.
6. Mesosphere - the layer begins at an altitude of 50 km with a thickness of about 30-40 km. The temperature drops by 0.25-0.3 0 C with an increase in altitude by 100 m.
7. The mesopause is the transitional layer between the mesosphere and the thermosphere. The temperature in this layer fluctuates at -90 0 C.
8. The thermosphere is the highest point of the atmosphere at a height of about 800 km. The temperature rises up to altitudes of 200–300 km, where values ​​of the order of 1500 K are reached, then fluctuates within this limit with increasing altitude. The region of the ionosphere, the place where air ionization occurs (“aurora borealis”) lies inside the thermosphere. The thickness of the layer depends on the level of solar activity.

There is a limit line that separates the Earth's atmosphere and outer space, called the Karman Line. Altitude 100 km above sea level.

Hydrosphere

The total volume of water on the planet is about 1390 million km 3, it is not surprising that 72% of the total area of ​​​​the Earth is occupied by oceans. The oceans are a very important part of geological activity. The mass of the hydrosphere is approximately 1.46 * 10 21 kg - this is almost 300 times more than the mass of the atmosphere, but a very small fraction of the mass of the entire planet.

The hydrosphere is divided into the World Ocean, groundwater and surface water.

The deepest point in the World Ocean (the Mariana Trench) is 10,994 meters, the average ocean depth is 3,800 m.

Surface continental waters occupy only a small share in the total mass of the hydrosphere, but nevertheless play a crucial role in the life of the terrestrial biosphere, being the main source of water supply, irrigation and watering. Moreover, this part of the hydrosphere is in constant interaction with the atmosphere and the earth's crust.

Solid water is called the cryosphere.

The water component of the planet's surface determines the climate.

The earth is represented as a magnet, approximated by a dipole (northern and southern polis). At the north pole, the lines of force go inward, and at the south pole they go out. In fact, at the north (geographic) pole there should be a south pole, and at the south (geographic) there should be a north one, but it was agreed on the contrary. The axis of rotation of the Earth and the geographic axis do not coincide, the difference in the center of divergence is about 420-430 km.

The magnetic poles of the Earth are not in one place, there is a constant shift. At the equator, the Earth's magnetic field has an induction of 3.05·10 -5 T and a magnetic moment of 7.91·10 15 Tl·m 3 . The strength of the magnetic field is not large, for example, the magnet on the cabinet door is 30 times stronger.

According to the residual magnetization, it was determined that the magnetic field changed its sign very many times, several thousand.

The magnetic field forms a magnetosphere, which delays the harmful radiation of the Sun.

The origin of the magnetic field remains a mystery to us, there are only hypotheses, they are that our Earth is a magnetic hydrodynamo. For example, Mercury has no magnetic field.

The time when the magnetic field appeared also remains a problem, it is known that it was 3.5 billion years ago. But more recently, data have appeared that in zircon minerals found in Australia, whose age is 4.3 billion years, there is residual magnetization, which remains a mystery.

The deepest place on Earth was discovered in 1875 - the Mariana Trench. The deepest point is 10994.

The highest point is Everest, Chomolungma - 8848 meters.

The deepest well in the world has been drilled on the Kola Peninsula, 10 km west of the city of Zapolyarny. Its depth is 12,262 meters.

Is there a point on our planet where we will weigh less than a mosquito? Yes, there is, the center of our planet, the force of gravitational attraction there is 0, thus, the weight of a person in the center of our planet is less than the weight of any insect on the surface of the Earth.

One of the most beautiful phenomena observed with the naked eye is the aurora borealis - the glow of the upper layers of the planet's atmosphere, which has a magnetosphere, due to their interaction with charged particles of the solar wind.

Antarctica keeps in itself 2/3 fresh water reserves.

If all the glaciers melt, the water level will rise by about 900 meters.

Every day, hundreds of thousands of tons of space dust fall on us, but almost everything burns up in the atmosphere.