The ancient Greeks tried to determine the real size of the Earth. But it was done with great precision 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 populated the entire planet, not everyone knows what the size of the Earth is.
The shape, movement and dimensions of the Earth
Most of all, the Earth resembles an ellipsoid, slightly flattened at both poles and somewhat stretched at the equator. What size is the earth? Its average radius is 6371 km.
The globe moves in a circular orbit around the sun, which is ideal for the existence of life. Our planet makes a complete revolution around its native star in 365.24 days. The unique tilt of the axis of the globe to the ecliptic plane and the speed of its rotation around the star have a decisive influence on the Earth’s climate - thanks to this there are seasons. The rotation around the axis determines the ideal ratio of day to night. Over time, the movement of the planet around its axis slows down. Of course, it is insignificant with respect to human longevity, but by universal standards this happens rather quickly - by 0.0015 seconds every century.
Mountainous terrain is more than a third of the entire land surface. Twenty percent is desert.
The emergence of the planet
According to modern concepts, the Earth was formed about 4.6-4.7 billion years ago. At first it was a protoplanetary cloud, which turned out to be captured by solar attraction. The very first rocks "matured" for almost 200 million years. The modern size of the Earth was formed about 3.5 billion years ago. Around this time, the conditions for the emergence of life. Man as a separate species appeared on Earth just 500 thousand years ago.
The 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 in 27.32166 days. Our satellite has a spherical shape. The tidal forces of the Earth over the past millennia have stopped its rotation around its own axis. The size of the moon and the earth used to be considered the same, but now we know that our planet is almost 81 times larger than the moon. The density of the satellite is also significantly less.
There are several theories of the origin of the satellite. One of them claims that the centrifugal forces of the nascent semi-liquid Earth threw out of it part of the terrestrial substance, which, due to the influence of magnetic and gravitational fields, could not fly into space and remained to rotate around the Earth, over time acquiring its shape.
Other scientists believe that the formation of the moon occurred without any “interference” of the Earth. It became a satellite much later when it fell under the action of planetary gravity.
The third theory says that the Moon and the Earth originated simultaneously from the same protoplanetary cloud. Completely none of the existing theories can explain the existence of the moon. Each of them has a contradiction and confirmation, but there is no clear answer at the moment.
Nevertheless, the most common version is that the Moon arose as a result of the collision of an not fully formed Earth with a huge celestial body measuring no less than Mars.
In the study of the internal structure of the globe play an important role seismic methods. These studies give reason to divide the Earth into several zones: the core, the crust and its mantle. On the outside is the bark - its thickness reaches 35 kilometers. It is divided into two main types: oceanic and continental. An intermediate type of crust forms on the boundary between land and ocean. Its thickness varies from 10 kilometers at the bottom of the seas to the mainland, whose crust is ten times thicker.
The many different elements that make up the earth are radioactive. When they decay, there is a huge amount of heat. In the center of the planet, the temperature reaches five thousand degrees Celsius. The highest temperature on the surface is recorded in the regions of Africa - +60 o C. The minimum - minus 90 o - in Antarctica.
The size of the planet Earth is almost the only indicator that is not influenced by human activity. Man has a huge impact on the bio and geosphere. Now the forces of scientists are focused on the question of how to minimize the pressure of civilization on the natural course of things.
Increased growth rates of humanity have highlighted the problems of adequate environmental management and nature conservation.