Astronomical views of all mankindformed by centuries. Starting with Ancient Egypt and, perhaps, even earlier civilizations, scientists directed their eyes to the sky, seeking to learn more about the structure of our world. Of course, the shape and dimensions of planet Earth were of interest.
Since then we have gone a long way. Enough of the facts can now be said for sure.
And one such question: 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 scholars 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 about what form the Earth has, the 4th grade of the school will say with full confidence.
Let's remember how things really are with the forms of our native planet.
In the past century, mankind has managed to makea big leap forward: launched the first spacecraft in the distant cosmic distance. The same brought (sent) scientists a photo of the planet. It turned out to be the most beautiful blue celestial body, but with the form there were some amendments.
So, on the new, most reliable information aboutplanet, 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 cosmonautics. Numerical expression of the planet's parameters will be necessary for accurate calculations. And then the shape of the Earth has its own characteristics.
For the section of general knowledge about the surrounding world, the term geoid is more commonly used. The latter, by the way, from Greek means literally "something like the Earth".
It is interesting to describe in mathematical waysthe shape of the Earth as an ellipsoid of revolution is not difficult. But as a geoid is almost impossible: to obtain the most accurate data you have to measure gravity at different points of the planet.
From all of the above, we are now going to consider some specific aspects of the whole topic. Now that we have learned what form the Earth really has, it will be interesting to understand why this is so.
Let's repeat:Our planet is slightly flattened from the poles, and not an ideal ball. Why is that? The answer is simple, obvious for anyone who has initial ideas about physics. When the Earth rotates around its axis, centrifugal forces arise in the equatorial regions. Accordingly, at the poles they can not be. So there was a difference in the radius of the polar and equatorial: the latter is somewhere more by 50 km.
As we know, the planet rotates not only aroundits axis, and 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. It was also found out that she acquired it because of the rotation.
But what form does the orbit of the Earth have?Around the Sun, she makes a path in the shape of an ellipse, being at different times of the year at different distances from the luminary. From being in this or that part of the orbit the season on the planet depends.
The state when the planet is furthest from the Sun is called the aphelion, the closest to it is the perihelion (both words are of Greek origin).
Finally, we will brighten up our article with vivid imagery, which was depicted by the predecessors of modern civilization. Fantasy they, I must say, was glorious.
To the question "What form does the Earth have?""An ancient Babylonian would argue that this is a huge mountain, on one of the slopes of which is their country, above it rises the dome - the sky, and it was hard as a stone.
The Indians were sure that the Earth rests on four elephants, which the turtle holds on its back, swimming in the dairy sea. The direction of elephant heads is the four directions of the world.
Only in the 8th-7th century BC. e.people began to gradually come to the conclusion that the Earth - something isolated from all sides, and does not stand on anything. The nightly disappearance of the Sun, which was awed by fear, pushed him towards him.
Roughly speaking, the Earth is round.For a man in the street 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 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. To take into account accurate data about the planet is important for obtaining correct calculations.
For a long time, the time has gone by when the EarthThey were carried on the backs of elephants or represented by a flat surface. Let us be initiated into the truth about the world around us and, being worthy of our time!
