Humans have been curious since the beginning of time. Finding names for everything on Earth has always been a priority. This includes knowing the measurements of everything and calling things by their proper names. We measure, weigh, and evaluate all objects in order to know exactly what we are dealing with. Our planet is no different. Although the Earth cannot be directly identified, its size has been estimated. diameter it has.
Do you want to know what is the diameter of the earth and how has it been calculated? Here we tell you everything.
Measure and label
Our planet still has many unknowns since it is not possible to directly measure all the variables in all corners. For example, the deepest seabed that exists, it is probably not yet available to our technology. Since the amount of sunlight diminishes under the sea and the pressure of the water shatters everything that is found, the bottoms of the largest sea trenches on Earth are completely unknown to us.
The same goes for the diameter of the Earth. We cannot dig and dig until we hit the core of the Earth. First, because the rock layers are too thick and tough for our technology to drill through. Second, because the temperature of the inner core it is hovering around 5000 degrees Celsius and there is no human or machine that can withstand such temperatures. Finally, at these depths there is no oxygen available to breathe.
However, although we cannot measure the diameter of the Earth directly, there are numerous methods that help to estimate it. For example, we can make use of seismic waves to study the composition of the inner layers of the Earth. Thanks to the indirect study methods of our planet, we can learn more about it without having to see them with our own eyes.
The theory of plate tectonics it tells us that the continental crust is divided into tectonic plates and that they are continuously displaced by convection currents in the Earth's mantle. These currents are given by difference in density between materials inside the Earth. We can know all this thanks to indirect measurement methods.
Eratosthenes, the first measurer of the diameter of the Earth
Since the human being has always been very curious, he has tried to find measures for everything. Eratosthenes was the first to be able to measure the diameter of the Earth. Something that has always been an enigma for people who lived in ancient times.
The way he measured the Earth consisted of some rudimentary elements that, at the time, was considered a revolutionary technology. The same goes for the cassette. Until recently VHS tapes were the latest technology. Now we can put more than 128GB in a device whose dimensions do not exceed the size of the nail of the big toe.
One of the most important elements that he used to measure the diameter of the Earth was measuring from the day of Summer Solstice. Eratosthenes picked up a papyrus from a library when he realized that a post did not reflect any shadow in Siena. This was because the sun's rays hit the Earth's surface in a perpendicular way. This is how his curiosity was aroused and he wanted to know how much the diameter of the Earth was.
Later he traveled to Alexandria, where I would repeat the experiment and see that the shadow was 7 degrees. After this measurement, he realized that the difference in that shadow with which he measured in Siena was reason enough to know that the Earth was round and not flat as believed. This was key to understanding the shape of our planet.
Eratosthenes Formula
From the experiences obtained in both measurements, he began to formulate a few theories that would help to measure the Earth's diameter. To do this, he began to deduce that, if a circumference has 360 degrees, the fiftieth of that circumference would be 7 degrees, that is to say, the same as the shadow measured in Alexandria. Knowing that the distance between the two cities is 800 kilometers, he was able to deduce that the earth's diameter could be about 40.000 kilometers.
Currently it is known that the diameter of the Earth is about 39.830 km. To be in an ancient time with hardly any measurements, he made some fairly exact measurements. Therefore, we must recognize the great work he did. We must also mention the importance of trigonometry, since thanks to it, he was able to know the diameter of the Earth.
Internal diameter
What Eratosthenes measured refers to the diameter of the earth's circumference. However, there are people who have also wanted to know what the internal diameter of the Earth is. Since it is not possible to go directly to the interior of the Earth's core for the aforementioned, it is necessary to pull indirect evidence.
For example, there are measurements of seismic waves that allow, knowing the differences between them, the type of material the interior is made of and the distance at which it is. This is how we know that the exterior of the mantle is composed of less dense materials that mix with those of higher density to create the convection currents responsible for the movement of the tectonic plates.
With these indirect methods it can be known that the diameter from the earth's surface to the opposite, passing through the core, is 12.756 km. As a curiosity, the deepest perforations that humans have made have not been able to exceed 15 km. It is as if of an apple in which we want to reach the bone of the interior, we had only torn the thin layer that covers it, that is, its skin.
As you can see, there are mathematicians with a curious and brilliant mind who have been able to make real discoveries with little technology. Because technology is only the means that facilitates knowledge.
