Education, The science
The density of the Earth. Exploring the Planet
The Earth is part of the solar system, located at a distance of 149.8 million kilometers from the Sun and is the fifth largest among other planets.
A little bit about the planet Earth
The speed of revolution of the celestial body around the Sun is 29.765 km / s. The total turnover it makes for 365.24 solar days.
Earth's mass and density
Its mass is 5.98 * 1024 kg, and the average density of the Earth is 5.52 g / cm 3 . At the same time, this figure near the earth's crust is within 2.71 g / cm 3 . From this it follows that the density of the planet Earth increases significantly towards the depth. This is due to the peculiarity of its structure.
The average density of the Earth was first determined by I. Newton, who calculated it at a rate of 5-6 g / cm 3 . Its chemical composition resembles the planets of the terrestrial group, such as Venus and Mars and in part Mercury. Composition of the Earth: iron - 32%, oxygen - 30%, silicon - 15%, magnesium - 14%, sulfur - 3%, nickel - 2%, calcium - 1.6% and aluminum - 1.5%. The remaining elements in the total account for about 1.2%.
Our planet is a blue traveler in space
Finding the Earth near the Sun affects the presence of certain chemicals in both liquid and gaseous states. Due to this the composition of the Earth is diverse, the atmosphere, hydrosphere and lithosphere were formed. The atmosphere consists mainly of a mixture of gases: nitrogen and oxygen 78% and 21%, respectively. And also carbon dioxide - 1.6% and an insignificant amount of inert gases, such as helium, neon, xenon and others.
The hydrosphere of our planet consists of water and occupies 3/4 of its surface. The Earth is the only known planet of the solar system, which has a hydrosphere. Water played a decisive role in the process of the origin of life on Earth. Due to its circulation and high heat capacity, the hydrosphere balances climatic conditions at different latitudes and forms a climate on the planet. It is represented by oceans, rivers and underground waters. The solid part of our planet consists of sedimentary formations, granite and basalt layer.
The structure of the Earth and its structure
The earth, like the rest of the terrestrial planets, has a layered inner structure. In its center is the core.
Complexity and inaccessibility of subsoil study
It is very difficult for a human to penetrate deep into the Earth. One of the deepest wells was drilled on the Kola Peninsula. Its depth reaches 12 kilometers.
We use indirect research tools
Because of this, the depths of our planet, located at considerable depth, are analyzed based on the results of seismic exploration. Every hour, about ten oscillations of its surface are recorded at different points of the Earth. Based on the data obtained, thousands of seismic stations conduct an investigation of the propagation of waves during an earthquake. These vibrations propagate just like the circles on the water from the abandoned object. When the wave penetrates into the more densified layer, its velocity changes abruptly. Using the obtained data, scientists were able to determine the boundaries of the inner shells of our planet. In the structure of the Earth, three main layers are distinguished.
Earth's crust and its properties
The upper shell of the Earth is the earth's crust. Its thickness can vary from 5 kilometers in the oceanic areas to 70 kilometers in the mountainous areas of the mainland. In relation to the whole planet, this shell is not thicker than the egg shell, and under it, underground fire rages. Echoes of deep processes occurring in the depths of the Earth, which we observe in the form of volcanic eruptions and earthquakes, cause great destruction.
The Earth's crust is the only layer that is accessible to people for life and full-scale research. The structure of the earth's crust under the continents and oceans is different.
The continental crust occupies a much smaller surface area of the earth, but has a more complex structure. It contains under the sedimentary layer the external granite and lower basaltic layers. In the continental crust there are more ancient rocks, the age of which is almost two billion years.
The oceanic crust is thinner, only about five kilometers, and contains two layers: the lower basaltic and the upper sedimentary. The age of oceanic rocks does not exceed 150 million years. In this layer, there can be life.
Mantle and what we know about her
Under the bark lies a layer called the mantle. The boundary between it and the bark is quite sharply marked. It is called the Mohorovich layer, and it can be found at a depth of about forty kilometers. The boundary of Mokhorovich consists mainly of basalts and silicates in a solid state. The exception is some "lava pockets", which are in liquid form.
How was knowledge about the mantle formed?
At the beginning of the 20th century, the boundary of Mohorovich was intensively discussed. Some researchers believed that it was there that a metamorphic process took place, in which rocks with high density were formed. Other scientists explained the sharp increase in the speed of motion of seismic waves by changing the content of rock composition from relatively light to more severe types.
Now this point of view is considered the main one in understanding and methods of studying the processes taking place inside the planet. The very mantle of the Earth is directly inaccessible to direct research due to its deep occurrence, and it does not surface.
The mantle, receiving radiation from the center, is heated from 800 degrees up to 2000 degrees near the core. It is assumed, in fact, that the substance of the mantle is in continuous motion.
What is the density of the Earth in the mantle region?
The density of the Earth within the mantle reaches about 5.9 g / cm 3 . The pressure increases with increasing depth and can reach 1.6 million atmospheres. In the matter of determining the temperature in the mantle, the opinions of scientists are not unambiguous and rather contradictory, 1500-10000 degrees Celsius. These are the opinions that have been established in academia.
The closer to the center, the hotter
In the center of the Earth there is a nucleus. Its upper part is located at a depth of 2900 kilometers from the surface (outer core) and is about 30% of the total mass of the planet. This layer has the properties of a viscous liquid and electrical conductivity. Contains about 12% sulfur and 88% iron. At the boundary of the nucleus and mantle, the density of the Earth sharply increases and reaches about 9.5 g / cm 3 . At a depth of about 5100 km, its inner part is recognized, its radius is about 1260 kilometers, and the mass is 1.7% of the total mass of the planet.
The pressure in the center is so huge that iron and nickel, which must be liquid, are in a solid state. According to scientific research, the center of the Earth is a place with ultra-extreme conditions with a pressure of 3.5 million atmospheres and a temperature above 6000 degrees.
In this regard, the iron-nickel alloy does not become liquid, despite the fact that the melting point of such metals is 1450-1500 degrees Celsius. Because of the giant pressure in the center, the mass and density of the Earth are huge enough. One cubic decimeter of the substance weighs about twelve and a half kilograms. This is a unique and unique place where the density of the planet is much higher than in any other layer of it.
To reveal all the mechanisms of interaction within the Earth would be not only interesting, but also useful. We would understand the formation of various minerals and their location. Perhaps, the mechanism of occurrence of earthquakes would be fully understood, which would give an opportunity to accurately warn them. Today they are unpredictable and bring many sacrifices and destruction. Accurate knowledge of convection flows and their interaction with the lithosphere, perhaps, will shed light on this problem. Therefore, the future scientists will have a long, interesting and useful work for all of humanity.
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