How much is the diameter of the Earth?

The diameter is a straight line through the center of a circle joining two opposite points. Therefore, the diameter of the Earth is used to measure in kilometers how much the interior of our planet measures. In addition, with this data, we can calculate its surface and even the perimeter of the Earth, always bearing in mind that it is a flattened sphere.

To find the first measurement of the diameter of the Earth you have to go back to year 240 BC It was the work of the Greek astronomer, geographer and mathematician Eratosthenes. According to his calculations, based on measuring the angle of the sun to illuminate the cities of Siena and Alexandria during the solstice, the diameter of the planet was 12,000 km. Modern science has shown that these data were close to reality.

The diameter of the Earth is 12,742 km. Today, this data is known with greater precision thanks to advances in seismology, a science that studies seismic waves.

Seismology, among many other things, uses seismic waves to find out how large the Earth is. It is based on studying the layer composition internal parts of the planet. With this type of indirect studies, it is possible to know more details of the Earth without having the need to verify them first hand.

Another formula to consider to get closer to knowing what the diameter of the Earth is is the one used by Eratosthenes. On June 21, during the summer solstice, he observed that a stick in his hand cast a shadow that had not been cast a few minutes before from another site. This is how he determined that the Earth was a round sphere and began to wonder how to calculate the diameter of the Earth.

Eratosthenes took care of measure angles formed by the shadows cast by the sticks located in Alexandria and Siena, respectively. The Greek mathematician was thus able to establish a difference of 7 degrees and, thanks to this data, he continued with the studies to determine the diameter of planet Earth.

After discovering how much the Earth measures from end to end, we have been able to fix more data on the measurements of the Earth. One of them is the perimeter, that is, the length of the planet’s contour.

The perimeter of the earth is 40,075 km. As early as the 3rd century BC, Eratosthenes went so far as to affirm that the circumference of the Earth was the equivalent of the sum of the surface of 250,000 stadiums of 160 meters each, adding up to an approximate total of 40,000 km.

Other data of interest about the Earth are the following:

• The border between Earth (atmosphere) and space is 100 km in altitude. This distance is called Kármán Line. In the first 11 km of height measured from the sea surface, there is 75% of the atmospheric mass.
• Within the solar system, planet Earth is the only one that has tectonic plates active, unless it is known. The surface of the planet is constantly changing due to the movement of the plates. These changes are responsible for the formation of volcanoes, mountains and seismic movements.
• Most of the Earth’s surface is covered by water. Specifically, it occupies 70%, that is, almost 3/4 of the planet’s surface. The water found on Earth is in a liquid, solid and gaseous state.
• As discussed above, the Earth is not a perfect sphere. The poles flatten the shape of the planet, turning it into a somewhat elliptical shape more than circumference.
• Despite countless known and ongoing investigations, Earth remains the only planet on which the existence of life.

Now that you know how big is the diameter of the earth and other data, you can learn more curiosities in the following articles:

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