The structure of the Earth

Our Earth is the only planet of the solar system on which life began. This became possible due to the presence of many components, of which it consists, the hydrosphere, the atmosphere, and also the internal structure of the Earth and a certain distance to the Sun had an important influence. The planet is an ellipsoid body consisting of several main shells, different in composition, chemical and physical properties.

The structure of the Earth is the subject of study of many scientists around the world, but only its upper part, the Earth's crust, has been thoroughly studied until now, and only theoretical assumptions exist about the remaining layers. The atmosphere and hydrosphere make up the gaseous and water envelopes of the Earth. And the internal structure of the Earth is represented by bark, mantle and core.

The outer shell is the atmosphere. It is gas, mainly composed of oxygen and nitrogen. In the solar system, there is no longer a planet with a similar chemical composition of the atmosphere, suitable for human life and all living things. Scientists consider its occurrence as the result of a long biological and chemical evolution. In the atmosphere, there are areas with different chemical composition, temperature, physical state, located in horizontal layers. For respiration and vital activity of man, only the lowest layer is suitable, the thickness of which does not exceed 4-5 km. The further up, the more the atmosphere is diluted. Its density decreases three times every 8 km (in altitude), while the temperature of the air decreases, which then increases at an altitude of 50 km in the stratosphere. Further in the mesosphere, the temperature drops again, and then in the thermosphere (above 180 km) it increases greatly. At an altitude of more than 1000 km, the exosphere begins. From it, the gases of the atmosphere are dissipated into outer space. The increase in temperature is interrelated with the ionization of atmospheric gases - the formation of electrically conductive layers, called the ionosphere.

Another significant difference of the Earth from the other planets of our system is the presence of a large number of surface waters, which are in proportionally distributed quantities in different aggregate states (solid, gaseous and liquid). The water shell of our planet is called the hydrosphere. On the planet, there are surface waters and internal waters.

The structure of the Earth - its interior, is studied using a seismic method, since now humanity has reached a level that has the technical ability to drill a bore hole up to 12 km deep. Seismologists investigate the propagation and occurrence of waves in different environments, at different depths. By changing their velocities and refraction, one can judge the heterogeneity and stratification of the deep layers of the planet. In addition to seismic, there are several other equally effective methods that help to study the geological structure of the Earth. Among them, gravimetric method, magnetometric method, etc.

The Earth's crust is under the hydrosphere or atmosphere. Its structure depends on this. The continental crust differs from the oceanic crust with more power and different composition. The oceanic crust occupies about 56% of the Earth's surface. Its power is almost no more than 5-6 km, it is maximum in the immediate vicinity of the continents. It consists of three layers: sedimentary, basaltic and a layer of full-crystalline igneous rocks.

The average thickness of the continental crust ranges from 35 to 40 km. It consists of three layers: a sedimentary layer, a continental crust layer and a granulite-basite layer.

Between the bark and the mantle is the surface of Mohorovicic (Moho). On the continents it is located at a depth of 25 to 75 km. After Moho there is a mantle. It distinguishes three layers, which differ somewhat from each other:

• Upper mantle (up to 410 km in depth);
• Average mantle (from 410 to 670 km);
• The lower mantle (670-2900 km).

The structure of the Earth is such that in the center of it there is a core consisting of two parts:

• Liquid outer part, is located at a depth of 2900-5146 km;
• Solid inner part, its depth is 5146-6371 km.

Most scientists claim that the core is iron with impurities of sulfur, nickel, silicon. The main magnetic field of our planet is generated by convection of the outer core.