This fact, probably, today no one doubts. Even little preschool children know that our planet has a spherical shape. But not all guys know why the Earth is round. Let's try to understand this issue in more detail.
The correct idea of why the Earth is round (now scientifically proven and reasonable) has not been formed in humans immediately and at the same time. Different peoples who inhabited our planet in ancient times had different theories about its appearance and structure. Here are some of them.
- In ancient India, the Earth was represented as a plane resting on the backs of three elephants. These giants are on a huge tortoise, and that, in turn, on a giant snake.
- The Egyptians considered the incarnation of the Sun of the god Ra, who in his chariot rushes through the dome of the sky. The land, in their view, was also flat.
- In ancient Babylon, there were notions of land in the form of a huge mountain, to the west of which Babylonia flourished. Around stretched the sea, on which the hard sky rests (and in the heavenly world there was also water and land, only inverted).
The Greeks also had very interesting ideas about the structure of the Universe (modern scientists know about them from the poems Iliad and Odyssey). The earth seemed to them a disk resembling a warrior's shield. Land is washed by the Ocean from all sides. The sun floats on the copper slope of the sky, which stretches above the surface. According to the philosopher Thales, the flat Earth floats in a bubble (which looks like a semicircle). The planet was perceived as the center of the universe, and the city of Delphi was considered the "navel of the earth." Sunrises and sunsets of the sun and the planets were based on the fact that they move in a circle.
Aristarchus of Samos
Interestingly, in ancient Greece, the followers of Pythagoras already considered the Earth and other planets round. A prominent astronomer of the then modernity, Aristarchus, expressed his opinion on the structure of the World. He, probably, was the first known scientist today who proved that the Earth is round and revolves around the Sun along with all the planets, and not vice versa. This was, according to some scientists, the impetus for the formation of the correct ideas of man about the structure of the planets and their movement through the celestial vault.
The earth is round and it spins! So, or almost so confidently announced - nationwide! - this great scientist, having blown up with his seditious statements the whole church and scientific world of that time. But even before that, pundits, in particular, Eratosthenes, argued that our planet has a spherical shape, and even managed to measure its diameter. Therefore, it is difficult to give an unequivocal answer to the question of who proved that the Earth is round. But back to Copernicus. The famous Polish astronomer lived and worked in the Renaissance. His observations, he marked the beginning of the scientific revolution. His work on the substantiation of the heliocentric scheme of the structure of the universe lasted for more than 40 years, until his death in 1543. Interestingly, the Copernicus book, On the Rotation of the Celestial Spheres (1543), estimated the size of the planets and the Sun itself, the distances between objects that are quite close to modern scientific data.
Why is the earth round?
Be that as it may, modern science is largely based on the above-mentioned research of the Polish astronomer, who was many centuries ahead of his time. And yet, why is the Earth round, not square and not flat, for example? Why were all the known planets of the Solar system, their satellites and the star itself - the Sun turned round? This fact has a very specific physical explanation. The thing is that in the universe there is a constant rotation. The earth rotates around its axis. The moon is around the earth. Our and other planets travel in certain orbits around a star (the Sun), which, in turn, is also subject to rotation. Even huge galaxies move in their trajectories, rotating.And the force of rotation and rotation acts on all sides of the surface of any planet at the same time, as a result giving them approximately the same distance from an imaginary center (in the global sense). That is why the Earth is round. For children, you can conduct an imaginary experiment. Imagine that our planet has some other form. With a strong rotation, the force of gravity will be so great that even a cube can turn into an ellipse or ball after some time.
Sphere or geoid?
Of course, the orbits of the planets are not perfectly round. Rather, they resemble elongated ellipses. By the way, the shape of our Earth is not an ideal ball, but a flattened ellipsoid (also called a geoid). And modern data on space exploration show that on the surface of our blue planet there are huge depressions (in the region of India - minus one hundred meters) and bulges (in the region of Iceland - to plus one hundred meters above the surface).From space, the Earth looks like a big, “bitten off” apple on one side. And from the poles "ball" visually looks pretty flat. After all, even the distance from the poles to the center is smaller than from the center to the equator, for many kilometers.