Interesting facts about the shape of the Earth.

Flat Earther vs Science! Let’s start the fight! A peaceful one, of course!

In everyday life, when it comes to the shape of the Earth, then most often you can hear that it is spherical. However, if we talk in more detail and more precisely about the shape of the Earth, then we can make some very, very interesting remarks.

So here are three interesting facts about the shape of the Earth:

1. Honestly, if you do not find fault too much, to a large extent, in a certain approximation, the statement about the sphericity of the Earth is actually true, and quite sufficient for simple reasoning and solving problems, where the accuracy of calculations does not exceed 0.5%.

But:
• First, we certainly understand that the surface of the Earth is not absolutely smooth, which means that it cannot be exactly spherical. There are many mountains and valleys on it, violating the strict definition for such a figure as a ball, where every point on the surface must be equidistant from the center.
• Secondly, even if we neglect the irregularities on the surface of the Earth, it is nevertheless also generally known that the Earth is slightly flattened from pole to pole (we are talking about geographic poles). This is due to the daily rotation of the Earth around its axis. Thus, the section of the Earth, more precisely, is not a circle, but rather an ellipse (or oval). A three-dimensional shape, which is an oblate ball, is called an ellipsoid of revolution. Thus, the Earth has the shape of an ellipsoid, which, nevertheless, is so weakly expressed that it is visually impossible to distinguish it from a sphere.
• It is also sometimes said that the Earth has the shape of a geoid. By definition, a geoid is a surface that is everywhere normal to gravity. And although, even the very name of this figure comes from the Greek phrase, literally meaning "something similar to the Earth" (that is, here it is not the Earth that has the shape of a geoid, but a geoid - the shape of the Earth), nevertheless, if we speak very strictly and meticulously, however, the Earth does not even have the shape of a geoid. The fact is that due to the influence of other large celestial bodies, primarily the Moon, which constantly act on the surface of the Earth, causing the ebb and flow, the shape of the Earth in general is constantly very slightly, but still changes depending on the relative position in relation to the Moon and other planets.

2. Sometimes you can come across the opinion that almost in the 15th century people considered the Earth flat, and only the discovery of America and the first round-the-world travels, which took place at the turn of the 15th and 16th centuries, proved the opposite. However, it is not. These trips were undertaken to achieve very different goals. And the fact that the Earth is not flat, but has the shape of a ball, was no secret already in the 6th century BC.

• Ancient Greek philosophers and thinkers, observing how ships go beyond the horizon, how lunar eclipses occur (when the round shadow of the Earth falls on the Moon), how celestial bodies move across the sky and how the picture of the starry sky changes if the observer moves along the Earth to the north or south, have understood that the Earth is spherical long ago.
• Apparently, the first person to express the idea of ​​the sphericity of the Earth was the ancient Greek scientist Parmenides. Also, Pythagoras and his teacher Anaximander of Miletus (who also claims to be the discoverer in this matter) did not doubt this. All these philosophers lived as already mentioned in the distant VI century BC. And since then, no one has seriously tried to refute the fact that the Earth is spherical, there have not even been any discussions about this, just all civilized and educated people knew that the Earth has the shape of a ball.
• Moreover, in the III century BC, Eratosthenes, knowing the distance from Alexandria to Siena and using the length of the shadow of the Library of Alexandria measured by him (which height was also known to him) during the position of the Sun over Siena at its zenith, was able to measure the length of the earth's meridian and calculate the Earth radius. Apparently, he counted 6287 kilometers in modern units then. Modern research shows that the radius of the Earth is on average 6371 kilometers. Thus, the accuracy of the calculations of Eratosthenes is simply amazing. Well, the first to show that the Earth actually has the shape of an ellipsoid was Isaac Newton.

3. And finally, one more interesting note about the shape of the Earth. The fact is that there are no objective grounds to expect that the shape of the Earth is exactly what we, its inhabitants, see and feel. For example, particles of solar radiation, being quite material objects, and moving at times with a speed very close to the speed of light, can also be quite rightly considered as objective observers. So in the frame of reference associated with these particles, the Earth, according to the theory of relativity, will contract in the direction of motion of these particles. And if some particle moves with a speed equal, for example, 99.999999991% of the speed of light, then the Earth will truly be a disk only a couple of tens of meters thick for it. A visual demonstration of the shape of the Earth depending on the speed of the observer is also shown in the figure below. However, all this does not mean at all that for us the Earth ceases to be spherical, or, more precisely, to have the shape of an ellipsoid or a geoid.

It should be noted that a circle is a flat figure. Round, for example, are pancakes, cymbals, music discs, and so on. You can often hear: "The earth is round." This will really be a mistake (of course, if it is not a particle of solar radiation that is moving at almost the speed of light), because this is the same as saying that the Earth is flat. Only the section of the Earth by a certain plane can be round. It is correct to say that the Earth has the shape of a ball. A ball is a three-dimensional figure. Balls, oranges, planets, and so on are spherical, for example.