Astronomical views of all mankind have been formed for centuries. Beginning with ancient Egypt and perhaps even earlier civilizations, scientists have turned their gaze to the sky, seeking to learn more about the structure of our world. I was interested, of course, in the shape and size of the planet Earth.
Since then we have gone a lot forward. Enough facts now we can say for sure.
And one of those questions: what shape does the Earth have? The history of various ideas about the shape of our planet is long and extremely interesting. It was built by respected pundits of modernity, the Middle Ages and Antiquity. For the truth (the one they adhered to), they were persecuted and even died. But they did not refuse the realized truth.
And now about the shape of the Earth, the 4th grade of the school will say with complete confidence.
Let's remember how things really are with the forms of our home planet.
Shape of the Earth
In the past century, humanity has managed to make a big leap forward: launched the first spacecraft indistant space distances. The same brought (sent) scientists a photo of the planet. It turned out to be the most beautiful blue celestial body, but there were some amendments to the shape.
So, according to the new, most reliable information about the planet, we know that the Earth is slightly flattened from the poles. That is, it is not a ball, but an ellipsoid of revolution, or a geoid. The choice between these two terms matters only in astrophysics, geodesy, and astronautics. The numerical expression of the parameters of the planet will be necessary for accurate calculations. And here the shape of the Earth has its own characteristics.
Numerical description of the shape of the planet
For the section of general knowledge about the surrounding world, it is more common to use the term geoid. The latter, by the way, literally means "something like the Earth" in Greek.
It is interesting that it is not difficult to describe the shape of the Earth as an ellipsoid of rotation in mathematical ways. But as a geoid, it is almost impossible: to obtain the most accurate data, you have to measure gravity at different points on the planet.
Why is the Earth oblate at the poles?
From all of the above, we now intend to consider some of the individual aspects of the whole topic. Now that we know what shape the Earth actually has, it will be interesting to understand why.
Repeat: our planet is slightly flattened at the poles, not a perfect ball. Why is that? The answer is simple, obvious to everyone who has an initial understanding of physics. When the Earth rotates around its axis, centrifugal forces arise in the regions of the equator. Accordingly, they cannot be at the polesmaybe. This is how the difference in the polar and equatorial radii was formed: the latter is larger by about 50 km.
Earth's orbit: what shape is it?
As we know, the planet rotates not only around its axis, but also makes a long journey around the center of the solar system. That conditional line along which it moves in outer space is called an orbit. We learned what shape the planet Earth has. Also found out that she got it because of the rotation.
But what is the shape of the Earth's orbit? It makes its way around the Sun in the form of an ellipse, being at different times of the year at different distances from the star. The season on the planet depends on staying in one or another part of the orbit.
The state when the planets are farthest from the Sun is called aphelion, closest to it - perihelion (both words of Greek origin).
Representations of ancient civilizations
Finally, let's brighten up our article with bright figurative pictures that the predecessors of modern civilization outlined for us. Their fantasy, I must say, was glorious.
To the question "What shape does the Earth have?" an ancient Babylonian would have argued that this is a huge mountain, on one of the slopes of which their country is located. Above it rises a dome - the sky, and it was hard as a stone.
The Indians were sure that the Earth rests on four elephants, which are held on its back by a turtle, swimming in the milky sea. The direction of the heads of the elephants is fourcardinal directions.
Only in the 8-7th century BC. e. people began to gradually come to the conclusion that the Earth is something isolated from all sides, and does not stand on anything. He was pushed by the nightly disappearance of the Sun, before which he felt awe.
Conclusion
Roughly speaking, the Earth is round. For the layman this will be enough, but not for certain sciences. Geodesy, astronautics, astrophysics need accurate data for calculations. And here the exact answer to the question of what shape the Earth has will come in handy. And this is a geoid, or an ellipsoid of revolution. The planet is flattened from the poles under the influence of centrifugal forces. Taking into account accurate data about the planet is important for obtaining correct calculations.
The times when the Earth was lifted up on the backs of elephants or represented as a flat surface have long sunk into oblivion. Let's be initiated into the truth about the world around us, and we, remaining worthy of our time!
