The astronomical views of all mankind have been shaped for centuries. Starting from Ancient Egypt and, possibly, even earlier civilizations, scientists turned their eyes to the sky, trying to learn more about the structure of our world. I was interested, of course, in the shape and size of planet Earth.
Since then we have gone a lot forward. Enough facts now we can say for sure.
And one of these questions: what form does the earth have? The history of diverse 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 from the realized truth.
And now, what form the Earth has, the 4th grade of the school will say with full confidence.
Let us recall how things really are with the forms of our home planet.
Earth shape
In the past century, mankind has managed to make a big leap forward: launched the first spacecraft in distant space distances. Those brought (sent) scientists photos of the planet. It turned out to be a beautiful blue celestial body, however, with the form, some corrections occurred.
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 geoid. The choice between these two terms matters only in astrophysics, geodesy, and astronautics. Numerical expression of the parameters of the planet will be necessary in accurate calculations. And then 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 world, it is more common to use the term geoid. The latter, by the way, from the Greek language literally means "something like the Earth."
Interestingly, it is not difficult to describe mathematically the shape of the Earth as an ellipsoid of revolution. But how a geoid is practically impossible: to obtain the most accurate data, one has to measure gravity at different points on the planet.
Why is the earth flattened from the poles?
From the foregoing, we now intend to consider some individual aspects of the whole topic. Now that we have learned what form the Earth actually has, it will be interesting to understand why this is so.
We repeat: our planet is a little flattened from the poles, and is not an ideal 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 poles. And so there was a difference in the radius of the polar and equatorial: the latter is more than somewhere around 50 km.
Earth orbit: what shape does it have?
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 planet Earth has. They also found out that she acquired it due to rotation.
But what shape does the Earth’s orbit have? Around the Sun, she makes her way in the form of an ellipse, being at different times of the year at different distances from the sun. The season on the planet depends on staying in a particular section of the orbit.
The condition when the planets farthest from the Sun is called aphelion, closest to it is perihelion (both words of Greek origin).
Representations of ancient civilizations
Finally, we brighten up our article with vivid figurative paintings that were described to us by the predecessors of modern civilization. Their fantasy, it must be said, was glorious.
To the question "What form does the earth have?" an ancient Babylonian would claim that it is a huge mountain, on one of the slopes of which their country is located. A dome rises above it - the sky, and it was as solid as stone.
The Indians were convinced that the Earth rests on four elephants, which are held on its back by a turtle, swimming in the sea of milk. The direction of the heads of elephants is the four cardinal points.
Only in the 8-7th century BC e. people gradually came to the conclusion that the Earth is something isolated from all sides, but does not stand on anything. The evening extinction of the Sun pushed toward him, awe of which was experienced.
Conclusion
Roughly speaking, the Earth is round. For the layman this will be enough, but not for certain sciences. In geodesy, astronautics, astrophysics, accurate data are needed for calculations. And here the exact answer to the question of what form the Earth has is already useful. And this is a geoid, or an ellipsoid of revolution. The planet under the influence of centrifugal forces is flattened from the poles. Considering accurate planetary data is important for getting the right calculations.
Long gone are the days when the Earth was elevated to the backs of elephants or represented as a flat surface. Let us be initiated in the truth about the world around us, and we, remaining worthy of our time!