Why the earth is round

Surely the easiest answer would be to say that the Earth is round because it cannot be otherwise, there is a physical reason that explains it, and this is none other than gravity. We say that the Earth is round because it cannot be anything else and that is, in the solar system. Any body that is more than 100 km in diameter has a rounded shape . This is due to the force of gravity, which acts with the same force in all directions. Since in large bodies not so much energy can be retained, they gradually adopt this rounded shape.

These can be somewhat difficult to understand, but you have to think of gravity as a force that comes from all directions with the same intensity, causing it to focus towards the center. Because it comes from all sides, over time, bodies that are massive enough to be affected by gravity end up turning round. Explaining it for children, or so that we all understand it, it is as if we take a piece of plasticine and, with closed hands, we apply the same force to its entire surface, when we release it it will have adopted the shape of the hollow of our hands.

This not only happens with the earth, it happens with any object in the solar system, both on a mobile phone and on large planets. The difference is that depending on the mass, the force of gravity is greater or lesser. The size of a mobile phone or a car is not enough for gravity to turn it into a sphere, however, in any celestial body over 100 km in diameter it is.

We have already explained that gravity is the cause that the Earth has a rounded shape, however, our planet is not a perfect round, but an oval sphere . But why does this happen? As you surely know, the Earth not only revolves around the Sun, but it also rotates on its own axis. This axis goes from Pole to Pole, from North to South, making these areas flatter than the Equator, since gravity is different in these areas. The spin of the Earth causes an outward centrifugal force. The same as the stone that shoots out of the sling. The further away from the axis of rotation – the equator – the greater is that force, while as it gets closer to the axis it goes down. Following the example of the sling, the shorter it is, the less the force with which the stone will be shot. Thus, the equator stands out more than the poles because the centrifugal force is greater, however, it does not stand out more because the force of gravity compensates for it.

Furthermore, our planet is itself irregular. For example, we have large mountain ranges and many valleys between which there are differences that reach kilometers. Its shape is not stable either, the gravity of the moon and the centrifugal force make it change, however, from space we see an almost perfect round. To explain this we must be clear that it is a simple matter of perspective . On a human scale, Everest may seem great to us, and it is, however, from space, these great mountains are just like a wrinkle on the face. In fact, if the size of the earth could be reduced and made as small as a billiard ball, the latter would have more imperfections and irregularities than our planet.

There has been a lot of ignorance on this subject, it is erroneously believed that the discovery that the Earth is round is something relatively modern, when the reality is that this is a widely spread and accepted concept since the times of ancient Greece . It is true that the first civilizations believed that the Earth was a flat surface, however, Greek authors such as Parmenides, Pythagoras or Plato already spoke with normality that the most probable thing is that the Earth was spherical, with such logical and simple arguments like the observation of the horizon, the maritime trips or the observation of the celestial bodies.

The fact that we think that the round earth was not a popular concept is probably due to one of the greatest historical errors in teaching in the world. There are many professors who explain that the objective of Columbus’s trip to the Indies was to show that the earth was round and, therefore, the Indies could be reached by surrounding the Earth. The reality is that everyone at that time assumed that the Earth was round and what Columbus defended is that its size was small enough to be able to reach the Indies without stopping.

The fact is that he was completely wrong, and if it weren’t for the fact that he encountered a new continent in his wake, he would never have made it to the Indies alive. We often look to the past with certain prejudices when the truth is that in many fields, our ancestors already had very modern conceptions of the world.