This fact, probably today already anybody does not cause doubts. Even small children know that our planet has a spherical shape. But not all guys know why the Earth is round. Let's try to find out more on this issue.
The correct idea of why the Earth is round (now scientifically proven and justified) has developed in people not at once and not simultaneously. Different peoples inhabiting our planet in ancient times, there were different theories of 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, is on a giant snake.
- The Egyptians considered the embodiment of the Sun of the god Ra, who in his chariot sweeps along the dome of the sky. The earth in their view was also flat.
- In Ancient Babylon it was common representations about land in the form of a huge mountain, in the West, which flourished Babylonia. Around stretched the sea, on which rests a solid heaven (and the heavenly world also had water and drying, only inverted).
The Greeks also had very interesting ideas about the structure of the Universe (modern scholars know about them from the poems "Iliad" and "Odyssey"). The earth seemed to them a disk, resembling the shield of a warrior. Land washed by the Ocean on all sides. The sun floats on the copper side of the sky that stretched above the surface. According to the philosopher Thales, flat Earth floats in a bubble (which looks like a semicircle). The planet was seen as the center of the Universe, Delphi was considered the "navel of the Earth". Sunrises and sunsets of the Sun and planets was 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 to be round. And the outstanding astronomer of modern times, Aristarchus, expressed his opinion on the question of the structure of the World. He, probably, was the first scientist known today who proved that the Earth is round and revolves around the Sun together with all the planets, and not vice versa. This served, in the opinion of some scientists, an impetus to the formation of the correct representations of man about the structure of the planets and their motion along the celestial vault.
The earth is round and it moves! So or nearly so confidently announced – nationwide! – this great scientist, blowing up their seditious utterances of the whole Church and the scientific world of that time. But before pundits, in particular, Eratosthenes, asserted that our planet is spherical in shape, and even managed to measure its diameter. So to give a definite answer to the question, who proved that the Earth is round, hard. However back to the Copernicus. The famous Polish astronomer lived and worked during the Renaissance. His observations he laid the Foundation for the scientific revolution. His work is devoted to the justification of the heliocentric scheme of the Universe, lasted more than 40 years, until his death in 1543. Interestingly, in the book of Copernicus "On the revolutions of heavenly spheres" (1543) the estimation of the size of the planets and the Sun, distances between objects, which is quite close to modern scientific data.
Why is the Earth round?
Anyway, modern science is largely based on the aforementioned research, the Polish astronomers, many centuries ahead of his time. Why the Earth is round, not square and not flat, for example? Why was rounded and all the known planets in the Solar system, their satellites and the very shining of the Sun? This fact has a very specific physical explanation. The thing is that in the Universe there is a constant rotation. The earth revolves around its axis. The moon around the Earth. Our and other planets travel in definite orbits around a star (the Sun), which, in turn, is also subject to rotation. Even huge galaxies move along their paths, revolving. And the force of gravitation and rotation acts on all sides of the surface of any planet at the same time, as a result giving them about the same distance from the imaginary center (in the global sense). That's why the Earth is round. For children, an imaginary experiment can be conducted. To imagine that our planet has some other form. With increased rotation, the gravitational force will be so great that even a cube can eventually turn into an ellipse or a ball.
A ball or a geoid?
Of course, the orbits of the planets are not perfectly round. Rather, they resemble elongated ellipses. By the way, and the shape of our Earth is not a perfect sphere, but a flattened ellipsoid (also called the geoid). And recent data on space exploration show that on the surface of our blue planet there is a huge basin (the area of India – minus one hundred meters) and the convexity (in the region of Iceland, up to one hundred meters above the surface). From space, the Earth looks like a large, "bitten off" on the one hand apple. And from the poles "ball" visually looks pretty flat. After all, even the distance from the poles to the center is less than from the center to the equator, for many kilometers.