The ancient Greeks tried to determine the real size of the Earth. But this was done with great accuracy only with the beginning of the space age. Although it must be said that the great scientists - Isaac Newton, Johann Kepler, Tycho Brahe used the laws and formulas they derived, to calculate the sizes of celestial bodies, and quite successfully. And although man has inhabited the entire planet, not everyone knows what the size of the Earth is.
The shape, motion and dimensions of the Earth
Most of all, the Earth resembles an ellipsoid, slightly oblate at both poles and somewhat stretched along the equator. What size is the Earth? Its average radius is 6,371 kilometers.
The globe moves in a circular orbit around the Sun, which is ideal for the existence of life. The complete revolution around the native star our planet makes for 365.24 days. The unique inclination of the axis of the globe to the plane of the ecliptic and the speed of its circulation around the luminary have a decisive influence on the Earth's climate - due to this, there are seasons. Rotation around the axis determines the ideal ratio of day to night. Over time, the motion of the planet around its axis slows down. Of course, relative to human life expectancy it is insignificant, but according to universal standards this happens quite quickly - by 0.0015 seconds every century.
The mountainous terrain is more than a third of the entire land surface. Twenty percent is occupied by the desert.
The origin of the planet
According to modern ideas, the Earth was formed about 4.6-4.7 billion years ago. At first it was a protoplanetary cloud, which was captured by the solar attraction. The very first rocks "matured" almost 200 million years. The modern size of the Earth was formed about 3.5 billion years ago. Approximately by this time, conditions for the birth of life were created. Man as a separate species appeared on Earth only 500 thousand years ago.
Earth, unlike other planets of our system, has only one natural satellite. The size of the Earth allows the Moon to make a full turn for 27,32166 days. Our satellite has a spherical shape. The tidal forces of the Earth over the past millennia stopped its rotation around its own axis. The size of the Moon and Earth used to be the same, but now we know that our planet is almost 81 times larger than the Moon. The density of the satellite is also much smaller.
There are several theories of the origin of the satellite. One of them claims that the centrifugal forces of the incipient semi-liquid Earth threw out of it a part of the terrestrial matter that, due to the influence of magnetic and gravitational fields, could not fly to space and remained rotating around the Earth, eventually acquiring its form.
Other scientists believe that the formation of the Moon occurred without any "interference" of the Earth. In the satellite, it turned much later, when it came under the action of planetary gravity.
The third theory says that the Moon and Earth originated simultaneously, from the same protoplanetary cloud. Completely none of the existing theories can explain the existence of the moon. Contradictions and confirmation are each of them, but there is no clear answer at the moment.
Nevertheless, the most common version - the Moon appeared as a result of a collision not fully formed Earth with a huge celestial body, which has dimensions not less than Mars.
Seismic methods play an important role in the study of the internal structure of the globe. These studies give grounds to divide the Earth into several zones: the core, the earth's crust and its mantle. On the outer side is the crust - its thickness reaches 35 kilometers. It is divided into two main types: oceanic and continental. At the boundary of land and ocean, an intermediate type of crust is formed. Its thickness varies from 10 kilometers at the bottom of the seas to the continental part, whose crust is thicker in dozens of times.
The many different elements that make up the Earth are radioactive. When they decay, a huge amount of heat is released. In the center of the planet, the temperature reaches five thousand degrees Celsius. The highest temperature on the surface was recorded in the regions of Africa - +60 о С. The minimum - minus 90 о - in Antarctica.
The size of the planet Earth is practically the only indicator that does not lend itself to the influence of human activity. The person has a huge impact on the bio- and the geosphere. Now the forces of scientists are aimed at solving the problem of how to minimize the pressure of civilization on the natural course of things.
The increased rates of growth in the number of mankind put the problems of adequate nature management and nature protection at the forefront.