The distance at which the stars are located is one of the factors why space is dark, although there is another reason. That is, the further away the stars are, the less bright they appear.
Although, for years the world has been wondering why space is dark. Although it seems like a simple question since the 16th century, reaching an accepted answer took even more time.
Astronomers estimate that there are about 200 billion trillion stars in the observable universe. And many of those stars are as bright or even brighter than our sun. So why is space dark?
Why is space dark if it is full of stars?
Brian Jackson, professor of Astronomy at Boise State University (United States) explained in an article that the farther away the stars are, the less bright they appear. To understand it, there is an example:
When we look at Jupiter through a telescope, for example, the image that our eyes can perceive is how it was 30 minutes ago, since this is the time it takes for light to travel to Earth. We notice this clearly with lightning: we always see its light before its sound. Therefore, Space is black because most of the light emitted by stars has not yet had time to reach us.
At some point, then, will the entire sky be completely illuminated by starlight reaching the earth? The answer is no. As the Astronomy professor clarifies, starlight performs the Doppler shift, that is, it turns into colors that are unattainable by the human eye.
How was that conclusion reached?
Until the 20th century, astronomers not only believed that it was impossible to count all the stars in the Universe. They also thought that the Universe was infinite.
To try to explain the paradox, some 19th century scientists postulated that the dust clouds between the stars must absorb a lot of starlight so that it would not be reflected back to us. But then they realized that the dust would absorb so much energy from the stars’ light that it would eventually shine as bright as the stars themselves.
The answer came hand in hand with a great change in knowledge: the general consensus now is that the Universe is not infinite. A Universe of limited size, even one with billions and billions of stars, simply cannot contain enough stars to illuminate all of space.
This is because the universe is not only finite in size, it is also finite in age, was born about 15 billion years ago in that fantastic explosion called the Big Bang, and since, cIt started at a single point and has been expanding ever since, Distant stars and galaxies are moving further and further away. Although nothing travels faster than light, it takes time for light to cross any distance.