From what distance can we see the spherical Earth?

Scientists envision flying off Earth so we can see our planet as a complete sphere. So how far will they have to fly?

The earth is round

It is interesting to note that already 2000 years ago, even though there were no satellites or modern technology, people knew that the Earth was spherical.

The Greeks were the ones who believed the earth was spherical before they had any proof. Prominent mathematician and philosopher Pythagoras was the first to hypothesize The earth is spherical from the 500s AD Pythagoras believed that in his eyes the sphere was the most perfect form.

Since British Columbia, many people believe that the Earth is spherical.

Since British Columbia, many people believe that the Earth is spherical. (Photo: Sohu)

A century later, the philosopher Plato also expressed the same opinion. However, the person who actually proved the earth to be spherical was the Greek philosopher – Aristotle. He gave evidence in the book”In Paradise” (On the Heɑvens) was written in 350 BC. According to Aristotle, we can only see the Earth’s shadow on the Moon during lunar eclipses. It is always spherical regardless of “where the Earth is on its ring”.

In another argument, he suggested that the positions of stars would be different if we looked at them from different places on Earth. The stars in Egypt, for example, are not visible in Cyprus at 1,000 km. This proves that the earth is not only round but also a sphere.

In Europe, the ancients also consciously believed that the Earth was spherical. In particular, after explorer Cerdinand Magellan’s ship circumnavigated the Earth, many people believed in the existence of the more spherical theory of the Earth.

How do you know that the Earth is spherical?

Many people think that by looking at the coastline they can prove that the earth is spherical. But scientists say that this method cannot observe the outline of the Earth’s circle.

Even using a telescope to look at the ocean, you won’t be able to prove the above point. Because, if you use a telescope you can clearly see the ocean coastline, if you use it on the ground you will see a horizon. However No matter where you stand, you stand on an arc of the Earth, your vision will be limitedthe degree of curvature of the Earth is different, and the distances between the arcs are also different.

Our land is not everywhere plain or bare

Our earth is not everywhere flat or bare, so it is very difficult to verify that all surfaces are curved. (Photo: Sohu)

This limitation of arcs can only prove that the earth has a curved surface, but cannot show whether other places are curved or not.

Our land is not everywhere in plains or bare lands, moreover, there are mountainous lands and high lands, so it is very difficult to verify that the surfaces are curved. Likewise, scientists have also said that humans, even standing on top of the highest mountain in the world like Everest, still cannot see the entire Earth.

How far away from the Earth do you have to go to see it spherical?

When we sit on the plane, we can see the mountains and the ground in a flat, square shape. The typical altitude of an airplane is between 7,000 and 12,000 meters. But from what the human eye sees when traveling by plane, this altitude still does not allow the spherical Earth to be seen clearly. Because the Earth is so large, for a sphere over 6,000 km in radius, an airplane flying 10,000 meters high cannot see the whole scene.

So what does Earth look like to astronauts in space?

Neil Armstrong saw the perfectly spherical Earth while standing on the Moon.

Neil Armstrong saw the Earth as perfectly spherical while standing on the Moon. (Photo: ohu)

According to the description of many astronauts, at an altitude of 118 km above sea level, they saw a faint blue star in their vision. This altitude can be considered the boundary between Earth and space. Beyond this height, it is clear that in the human eye, the Earth can be seen as a sphere.

American Astronaut – Neil Armstrong once said, as he stood on the Moon, he saw the Earth completely and was stunned by the scene before his eyes.

In fact, 1,000 km above the Earth’s surface, astronauts can see the largest arc on Earth’s edge when looking out of windows. If you increase the altitude to 2000 km, at this distance the astronaut can clearly see the arc of the Earth. And of course, at a distance of about 400 km from the Earth’s surface like the International Space Station, astronauts can easily see the spherical Earth in the clearest way.

Article source: PNVN