Who warms up the earth's core? What is the core of the earth made of?

In the twentieth century, through numerous studies, mankind revealed the secret of the earth's interior, the structure of the earth in the context became known to every schoolchild. For those who do not yet know what the earth consists of, what are its main layers, their composition, what is the name of the thinnest part of the planet, we will list a number of significant facts.

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The shape and size of the planet Earth

Contrary to popular misconception our planet is not round. Its shape is called the geoid and is a slightly flattened ball. The places where the globe is compressed are called poles. The axis of the earth's rotation passes through the poles, our planet makes one revolution around it in 24 hours - an earth day.

In the middle, the planet is surrounded by an imaginary circle dividing the geoid into the Northern and Southern hemispheres.

Apart from the equator there are meridians - circles perpendicular to the equator and passing through both poles. One of them, passing through the Greenwich Observatory, is called zero - it serves as a reference point for geographic longitude and time zones.

The main characteristics of the globe include:

diameter (km.): equatorial - 12 756, polar (near the poles) - 12 713;
length (km.) of the equator - 40,057, meridian - 40,008.

So, our planet is a kind of ellipse - a geoid, rotating around its axis passing through two poles - North and South.

The central part of the geoid is surrounded by the equator - a circle dividing our planet into two hemispheres. In order to determine what the radius of the earth is, use half the values of its diameter at the poles and the equator.

And now about that what is the earth made of what shells it is covered with and what sectional structure of the earth.

Earth shells

Basic shells of the earth distinguished according to their content. Since our planet is spherical, its shells held together by gravity are called spheres. If you look at s trinity of the earth in a section, then three areas can be seen:

In order(starting from the surface of the planet) they are located as follows:

The lithosphere is a solid shell of the planet, including mineral layers of the earth.
Hydrosphere - contains water resources - rivers, lakes, seas and oceans.
Atmosphere - is a shell of air that surrounds the planet.

In addition, the biosphere is also distinguished, which includes all living organisms that inhabit other shells.

Important! Many scientists refer the population of the planet to a separate vast shell called the anthroposphere.

The earth's shells - the lithosphere, hydrosphere and atmosphere - are distinguished according to the principle of combining a homogeneous component. In the lithosphere it is hard rocks, soil, the internal contents of the planet, in the hydrosphere - all of it, in the atmosphere - all the air and other gases.

Atmosphere

The atmosphere is a gaseous envelope its composition includes: , nitrogen, carbon dioxide, gas, dust.

Troposphere - the upper layer of the earth, containing most of the earth's air and extending from the surface to a height of 8-10 (at the poles) to 16-18 km (at the equator). Clouds and various air masses form in the troposphere.
The stratosphere is a layer in which the air content is much lower than in the troposphere. His average thickness is 39-40 km. This layer begins at the upper boundary of the troposphere and ends at an altitude of about 50 km.
The mesosphere is a layer of the atmosphere that extends from 50-60 to 80-90 km above earth's surface. Characterized by a steady decrease in temperature.
Thermosphere - located 200-300 km from the surface of the planet, differs from the mesosphere by an increase in temperature as altitude increases.
Exosphere - begins with the upper boundary lying below the thermosphere, and gradually passes into outer space, it is characterized by low air content, high solar radiation.

Attention! In the stratosphere at an altitude of about 20-25 km there is a thin layer of ozone that protects all life on the planet from harmful ultraviolet rays. Without it, all living things would have perished very soon.

The atmosphere is the earth's shell, without which life on the planet would be impossible.

It contains the air necessary for the breathing of living organisms, determines suitable weather conditions, protects the planet from negative impact solar radiation.

The atmosphere consists of air, in turn, air is approximately 70% nitrogen, 21% oxygen, 0.4% carbon dioxide and other rare gases.

In addition, there is an important ozone layer in the atmosphere, at about 50 km altitude.

Hydrosphere

The hydrosphere is all the liquids on the planet.

This shell by location water resources and their degree of salinity includes:

the world ocean is a huge space occupied by salt water and includes four and 63 seas;
the surface waters of the continents are freshwater, as well as occasionally brackish water bodies. They are subdivided according to the degree of fluidity into reservoirs with a course - rivers on and reservoirs with stagnant water - lakes, ponds, swamps;
groundwater - fresh water below the earth's surface. Depth their occurrence varies from 1-2 to 100-200 and more meters.

Important! Great amount fresh water is currently in the form of ice - today in zones permafrost in the form of glaciers, huge icebergs, permanent non-melting snow, there are about 34 million km3 of fresh water reserves.

The hydrosphere is primarily, source of fresh drinking water, one of the main climate-forming factors. Water resources are used as means of communication and objects of tourism and recreation (recreation).

Lithosphere

The lithosphere is solid ( mineral) layers of the earth. The thickness of this shell ranges from 100 (under the seas) to 200 km (under the continents). The lithosphere includes the earth's crust and upper part mantle.

What is located below the lithosphere is directly the internal structure of our planet.

The slabs of the lithosphere mainly consist of basalt, sand and clay, stone, and also the soil layer.

The scheme of the structure of the earth together with the lithosphere is represented by the following layers:

Earth's crust - upper, consisting of sedimentary, basalt, metamorphic rocks and fertile soil. Depending on the location, there are continental and oceanic crust;
mantle - is under the earth's crust. Weighs about 67% of total weight planets. The thickness of this layer is about 3000 km. Upper layer the mantle is viscous, lies at a depth of 50-80 km (under the oceans) and 200-300 km (under the continents). The lower layers are harder and denser. The composition of the mantle includes heavy iron and nickel materials. The processes occurring in the mantle determine many phenomena on the surface of the planet (seismic processes, volcanic eruptions, formation of deposits);
The central part of the earth is the core, consisting of an inner solid and an outer liquid part. The thickness of the outer part is about 2200 km, the inner one is 1300 km. Distance from surface d about the core of the earth is about 3000-6000 km. The temperature in the center of the planet is about 5000 Cº. According to many scientists, the core land by composition is a heavy iron-nickel melt with an admixture of other elements similar in properties to iron.

Important! Among narrow circle scientists, in addition to the classical model with a semi-molten heavy core, there is also a theory that in the center of the planet there is an inner luminary, surrounded on all sides by an impressive layer of water. This theory, in addition to a small circle of adherents in the scientific community, has found wide circulation in science fiction literature. An example is the novel by V.A. Obruchev "Plutonia", which tells about the expedition of Russian scientists to the cavity inside the planet with its own small luminary and the world of animals and plants extinct on the surface.

Such a common earth structure map, including the earth's crust, mantle and core, every year more and more improved and refined.

Many parameters of the model with the improvement of research methods and the advent of new equipment will be updated more than once.

For example, in order to know exactly how many kilometers to outer part of the nucleus, it will take more years of scientific research.

On the this moment the deepest shaft in the earth's crust, dug by man, is about 8 kilometers, so the study of the mantle, and even more so the core of the planet, is possible only in a theoretical context.

Layered structure of the Earth

We study what layers the Earth consists of inside

Conclusion

Having considered sectional structure of the earth we have seen how interesting and complex our planet is. The study of its structure in the future will help humanity to understand the mysteries natural phenomena, will make it possible to more accurately predict devastating natural disasters, to discover new, yet undeveloped mineral deposits.

Our planet Earth has a layered structure and consists of three main parts: the earth's crust, mantle and core. What is the center of the earth? Nucleus. The depth of the core is 2900 km, and the diameter is approximately 3.5 thousand km. Inside - a monstrous pressure of 3 million atmospheres and an incredibly high temperature - 5000 ° C. In order to find out what is in the center of the Earth, it took scientists several centuries. Even modern technology could not penetrate deeper than twelve thousand kilometers. The deepest borehole, located on the Kola Peninsula, has a depth of 12,262 meters. Far from the center of the earth.

The history of the discovery of the earth's core

One of the first to guess about the presence of a nucleus in the center of the planet was the English physicist and chemist Henry Cavendish at the end of the 18th century. With the help of physical experiments, he calculated the mass of the Earth and, based on its size, determined the average density of the substance of our planet - 5.5 g / cm3. The density of known rocks and minerals in the earth's crust turned out to be approximately two times less. From this followed a logical assumption that in the center of the Earth there is an area of denser matter - the core.

In 1897, the German seismologist E. Wiechert, studying the passage of seismological waves through the inner parts of the Earth, was able to confirm the assumption of the presence of a core. And in 1910, the American geophysicist B. Gutenberg determined the depth of its location. Subsequently, hypotheses about the process of formation of the nucleus were also born. It is assumed that it was formed as a result of the settling of heavier elements to the center, and initially the substance of the planet was homogeneous (gaseous).

What is the core made of?

It is quite difficult to study a substance whose sample cannot be obtained in order to study its physical and chemical parameters. Scientists have only to assume the presence of certain properties, as well as the structure and composition of the nucleus by indirect signs. Especially helpful in the study of the internal structure of the Earth was the study of the propagation of seismic waves. Seismographs, located at many points on the surface of the planet, record the speed and types of passing seismic waves arising from tremors of the earth's crust. All these data make it possible to judge internal structure Earth, including the core.

To date, scientists suggest that the central part of the planet is heterogeneous. What is at the center of the earth? The part adjacent to the mantle is a liquid core, consisting of molten matter. Apparently, it contains a mixture of iron and nickel. This idea led scientists to the study of iron meteorites, which are pieces of asteroid nuclei. On the other hand, the obtained iron-nickel alloys have more high density than the estimated core density. Therefore, many scientists tend to assume that in the center of the Earth, the core, there are also lighter chemical elements.

The presence of a liquid core and the rotation of the planet around its own axis of geophysics explain the existence magnetic field. It is known that an electromagnetic field around a conductor arises when current flows. The molten layer adjacent to the mantle serves as such a giant current-carrying conductor.

Inner part the nucleus, despite the temperature of several thousand degrees, is a solid. This is due to the fact that the pressure in the center of the planet is so high that hot metals become solid. Some scientists suggest that the solid core consists of hydrogen, which, under the influence of incredible pressure and enormous temperature, becomes like a metal. Thus, what is the center of the Earth, even geophysicists are still not known for certain. But if we consider the issue from a mathematical point of view, then we can say that the center of the Earth is approximately 6378 km. from the surface of the planet.

After dropping the keys into the molten lava flow, say goodbye to them, because, well, dude, they are everything.
- Jack Handy

Looking at our home planet, you can see that 70% of its surface is covered with water.

We all know why this is so: because the Earth's oceans rise above the rocks and mud that make up the land. The concept of buoyancy, in which less dense objects float above denser objects that sink below, explains much more than just oceans.

The same principle that explains why ice floats in water, a helium balloon rises in the atmosphere, and rocks sink in a lake, explains why the layers of planet Earth are arranged the way they are.

The least dense part of the Earth, the atmosphere, floats above water oceans that float above the Earth's crust, which sits above the denser mantle that does not sink into the Earth's densest part: the core.

Ideally, the most stable state of the Earth would be one that would ideally be layered, like an onion, with the densest elements in the center, and as you move outward, each successive layer would consist of less dense elements. And every earthquake actually moves the planet towards that state.

And this explains the structure of not only the Earth, but all the planets, if you remember where these elements came from.

When the universe was young - only a few minutes old - only hydrogen and helium existed. More and more heavy elements were created in the stars, and only when these stars died did the heavy elements go out into the Universe, allowing new generations of stars to form.

But this time, the mixture of all these elements - not only hydrogen and helium, but also carbon, nitrogen, oxygen, silicon, magnesium, sulfur, iron and others - forms not only a star, but also a protoplanetary disk around this star.

Pressure from the inside out in a forming star pushes lighter elements out, and gravity causes irregularities in the disk to collapse and form planets.

When solar system four inner peace are the densest of all planets in the system. Mercury is made up of the densest elements that could not hold a large number of hydrogen and helium.

Other planets, more massive and more distant from the Sun (and therefore receiving less of its radiation), were able to hold more of these ultra-light elements - this is how the gas giants formed.

In all worlds, as on Earth, on average, the densest elements are concentrated in the core, while the lungs form progressively less dense layers around it.

Not surprisingly, iron, the most stable element, and the heaviest element created in large quantities on the border of supernovae, and there is the most common element of the earth's core. But perhaps it will be surprising that between hard core and a solid mantle is a liquid layer more than 2000 km thick: the outer core of the Earth.

The Earth has a thick liquid layer containing 30% of the planet's mass! And we learned about its existence by a rather ingenious method - thanks to seismic waves coming from earthquakes!

Seismic waves of two types are born in earthquakes: the main compressional, known as P-wave, passing along the longitudinal path

And the second shear wave, known as the S-wave, similar to the waves on the surface of the sea.

Seismic stations around the world are capable of picking up P- and S-waves, but S-waves do not travel through liquid, and P-waves not only travel through liquid, they are refracted!

As a result, it can be understood that the Earth has a liquid outer core, outside of which there is a solid mantle, and inside - a solid inner core! This is why the Earth's core contains the heaviest and densest elements, and this is how we know that the outer core is a liquid layer.

But why is the outer core liquid? Like all elements, the state of iron, whether solid, liquid, gaseous, or otherwise, depends on the pressure and temperature of the iron.

Iron is a more complex element than many you are familiar with. Of course, it may have different crystalline solids, as shown in the graph, but we are not interested in normal pressures. We are descending to the core of the earth, where pressures are a million times higher than at sea level. And what does the phase diagram look like for such high pressures?

The beauty of science is that even if you don't immediately have an answer to a question, chances are someone has already done it. the right research where you can find the answer! In this case, Ahrens, Collins and Chen in 2001 found the answer to our question.

And although the diagram shows gigantic pressures up to 120 GPa, it is important to remember that the pressure of the atmosphere is only 0.0001 GPa, while in the inner core the pressures reach 330-360 GPa. The top solid line shows the boundary between melting iron (top) and solid (bottom). Did you notice how the solid line at the very end makes a sharp upward turn?

In order for iron to melt at a pressure of 330 GPa, an enormous temperature is required, comparable to that which prevails on the surface of the Sun. The same temperatures at lower pressures will easily maintain iron in liquid state, and at higher - in the solid. What does this mean in terms of the Earth's core?

This means that as the Earth cools, its internal temperature drops, while the pressure remains unchanged. That is, during the formation of the Earth, most likely, the entire core was liquid, and as it cools, the inner core grows! And in the process, since solid iron has a higher density than liquid iron, the Earth is slowly shrinking, which leads to earthquakes!

So the Earth's core is liquid because it's hot enough to melt iron, but only in regions where the pressure is low enough. As the Earth ages and cools, more and more of the core becomes solid, and so the Earth shrinks a bit!

If we want to look far into the future, we can expect the same properties that are observed in Mercury.

Mercury, due to its small size, has already cooled and contracted significantly, and has cracks hundreds of kilometers long due to the need for contraction due to cooling.

So why does the Earth have a liquid core? Because she hasn't cooled yet. And each earthquake is a small approximation of the Earth to the final, cooled down and solid state through and through. But don't worry, the Sun will explode long before then, and everyone you know will be dead for a very long time.

After dropping the keys into the molten lava flow, say goodbye to them, because, well, dude, they are everything.
- Jack Handy

Looking at our home planet, you can see that 70% of its surface is covered with water.

The same principle that explains why ice floats in water, a helium balloon rises in the atmosphere, and rocks sink in a lake, explains why the layers of planet Earth are arranged the way they are.

And this explains the structure of not only the Earth, but all the planets, if you remember where these elements came from.

Pressure from the inside out in a forming star pushes lighter elements out, and gravity causes irregularities in the disk to collapse and form planets.

In the case of the solar system, the four inner worlds are the densest of all the planets in the system. Mercury is made up of the densest elements that could not hold large amounts of hydrogen and helium.

Other planets, more massive and more distant from the Sun (and therefore receiving less of its radiation), were able to hold more of these ultra-light elements - this is how the gas giants formed.

In all worlds, as on Earth, on average, the densest elements are concentrated in the core, while the lungs form progressively less dense layers around it.

Not surprisingly, iron, the most stable element, and the heaviest element created in large quantities at the supernova edge, is the most abundant element in the Earth's core. But perhaps surprisingly, between the solid core and the solid mantle lies a liquid layer more than 2,000 km thick: Earth's outer core.

The Earth has a thick liquid layer containing 30% of the planet's mass! And we learned about its existence by a rather ingenious method - thanks to seismic waves coming from earthquakes!

Seismic waves of two types are born in earthquakes: the main compressional, known as P-wave, passing along the longitudinal path

And the second shear wave, known as the S-wave, similar to the waves on the surface of the sea.

Seismic stations around the world are capable of picking up P- and S-waves, but S-waves do not travel through liquid, and P-waves not only travel through liquid, they are refracted!

But why is the outer core liquid? Like all elements, the state of iron, whether solid, liquid, gaseous, or otherwise, depends on the pressure and temperature of the iron.

Iron is a more complex element than many you are familiar with. Of course, it can have different crystalline solids, as shown in the graph, but we are not interested in ordinary pressures. We are descending to the core of the earth, where pressures are a million times higher than at sea level. And what does the phase diagram look like for such high pressures?

The beauty of science is that even if you don't immediately have an answer to a question, chances are that someone has already done the right research in which to find the answer! In this case, Ahrens, Collins and Chen in 2001 found the answer to our question.

In order for iron to melt at a pressure of 330 GPa, an enormous temperature is required, comparable to that which prevails on the surface of the Sun. The same temperatures at lower pressures will easily maintain iron in a liquid state, and at higher pressures in a solid state. What does this mean in terms of the Earth's core?

If we want to look far into the future, we can expect the same properties that are observed in Mercury.

Mercury, due to its small size, has already cooled and contracted significantly, and has cracks hundreds of kilometers long due to the need for contraction due to cooling.

In what time immemorial did this happen? All these questions have long troubled mankind. And many scientists wanted to quickly find out what is there, in the depths? But it turned out that to study all this is not so easy. After all, even today, having all the modern devices for conducting all kinds of research, humanity is able to drill wells into the bowels of only some fifteen kilometers - no more. And for full-fledged and comprehensive experiments, the required depth should be an order of magnitude greater. Therefore, scientists have to calculate how the Earth's core was formed using a variety of high-precision instruments.

Exploring the Earth

Since ancient times, people have studied rocks, naked in a natural way. Cliffs and slopes of mountains, steep banks of rivers and seas... Here you can see with your own eyes what probably existed millions of years ago. And in some suitable places wells are being drilled. One of these - at its depth - fifteen thousand meters. The mines that people break through for also help to study the inner Core, of course, they cannot “get it”. But on the other hand, from these mines and wells, scientists can extract rock samples, learning in this way about their change and origin, structure and composition. The disadvantage of these methods is that they are able to explore only the land and only the upper part of the Earth's crust.

Recreating Conditions at the Earth's Core

But geophysics and seismology, the sciences of earthquakes and the geological composition of the planet, help scientists to penetrate deeper and deeper without contact. By studying seismic waves and their propagation, it turns out what both the mantle and the core consist of (it is determined similarly, for example, with the composition of fallen meteorites). Such knowledge is based on the received data - indirect - about physical properties substances. Also today, the study is facilitated by modern data obtained from artificial satellites in orbit.

The structure of the planet

Scientists managed to understand, summarizing the data obtained, that the structure of the Earth is complex. It consists of at least three unequal parts. In the center is a small core, which is surrounded by a huge mantle. The mantle occupies about five-sixths of the total globe. And from above everything is covered by a rather thin outer crust of the Earth.

The structure of the nucleus

The core is the central, middle part. It is divided into several layers: internal and external. According to most modern scientists, the inner core is solid, and the outer one is liquid (it is in a molten state). And the core is very heavy: it weighs more than a third of the mass of the entire planet with a volume of just over 15. In the core, the temperature is quite high, it ranges from 2000 to 6000 degrees Celsius. According to the assumptions of science, the center of the Earth consists mainly of iron and nickel. The radius of this heavy segment is 3470 kilometers. And its surface area is about 150 million square kilometers, which is approximately equal to the area of all the continents on the surface of the Earth.

How was the Earth's core formed?

There is very little information about the core of our planet, and it can only be obtained indirectly (there are no core rock samples). Therefore, theories can be expressed only hypothetically about how the core of the Earth was formed. The history of the Earth is billions of years old. Most scientists adhere to the theory that in the beginning the planet formed as a fairly homogeneous one. The process of isolating the nucleus began later. And its composition is nickel and iron. How was the Earth's core formed? The melt of these metals gradually descended to the center of the planet, forming the core. This was due to more specific gravity melt.

Alternative theories

There are also opponents of this theory, who bring their own, quite reasonable arguments. First, these scientists question the passage of an alloy of iron and nickel to the center of the nucleus (and this is more than 100 kilometers). Secondly, if we assume the release of nickel and iron from silicates similar to meteoric ones, then the corresponding reduction reaction should have occurred. It, in turn, should have been accompanied by the release of a huge amount of oxygen, forming Atmosphere pressure several hundred thousand atmospheres. And there is no evidence of the existence of such an atmosphere in the past of the Earth. Therefore, theories were put forward about the initial formation of the core during the formation of the entire planet.

In 2015, Oxford scientists even proposed a theory according to which the core of the planet Earth consists of uranium and has radioactivity. This indirectly proves both such a long existence of the magnetic field near the Earth, and the fact that at the present time our planet radiates much more heat than was assumed by previous scientific hypotheses.