With all of these stars shining light ... why does the night sky look dark?

Laila Ali

Why does the night sky appear dark despite so many stars that we cannot even count in a small area of ​​the sky above our heads?

Perhaps the matter is not a great mystery, perhaps the answer lies in the fact that the universe is very massive and no matter how filled with glowing stars, it will remain like the small candles that we light in a dark city, you see whether the candles will light that city on its large or will it remain candles with limited lighting compared to the vast dark area around it?

In the 1920s, the German astronomer Heinek Olbers posed this question, and despite the fact that glowing stars and galaxies radiate through the universe, the universe is pervaded by total darkness rather than lit. This apparent paradox is known as the "Olbers' Paradox".

Based on our understanding of the universe at the time, Olbers' paradox tells us that it is a constant that does not change and that it is infinitely old - that the night sky should not be dark, and it should be as bright as the sun shining in all directions.

What direction you look at, you will find a lit star, and because the universe is infinitely old, the distant stars have had enough time to reach our light, so why is the night sky so dark?

Possible explanations
Over the years, there have been many attempts to explain the Olpers paradox, one of which considered interstellar dust and possibly intergalactic to be the cause.

The idea was that dust blocks the light coming from distant objects, making the sky dark, so if your car or home windows are dusty, for example, it is difficult to see through them.

Therefore, there could simply be a lot of dust blocking all of this light, and astronomers quickly realized that this could not be the reason. Although dust absorbs starlight, it will eventually heat it up, and it will glow how much the light source glows, too. There is not enough dust to cause this phenomenon.

Another suggested explanation is that, if there are an infinite number of stars, they may clump together and hide behind each other. This interpretation can be partially correct. There may be stars stacked behind each other in a kind of linear structure that is hidden from our eyes.

The most plausible explanation
But the most likely explanation became apparent when the astronomer Edwin Hubble discovered that the universe is in a state of continuous expansion and expansion, then the evidence rolled up to the Big Bang theory that tells us that the universe had a beginning, which is the thing that began after this expansion, and this means that our world is not old without borders .

This variable, unstable universe that had a starting point resulted in two main possibilities regarding the night sky, the first of which is that the expanding universe causes the waves of light that try to reach our eyes to expand from the stars and distant galaxies, causing the wavelength to change.

This is called the "red shif", that is, the wavelength of light emitted due to the expansion of the universe, and it is responsible for the light output from the visible range to the invisible infrared range.

Consequently, the expansion of the universe means that the visible light emitted by stars can eventually extend into a light that we can no longer see, giving us the dark night sky.

The second, and perhaps most importantly, is that in a world that is infinitely old and there is not enough time for light from all the far corners of the universe to reach us, we can only see something when the light that emits it reaches us.

In our daily life, the delay at the time of the light's arrival is small and does not make a difference. When the electric lamp lights up, you receive the light, but when the distance between you and the source of this light increases, the delay increases when the light reaches you.

For example, it takes eight minutes for light to travel from the sun to us here on Earth, as light takes four years to reach us from the nearest star after our sun, which is the Proxima Centauri star, and the journey to Andromeda - the closest massive galaxy to our galaxy - takes 2.5 one million years.

So when the universe becomes larger, these time distances become farther away, and in the end the maximum that we can receive light from is 13.8 billion years, which is the known age of the universe.

Thus, if the star is far enough that it may take more than 13.8 billion years for its light to reach us here on Earth, that light may still be on its way to us.

The last part of the possible explanation lies in the fact that the stars and galaxies are not immortal, they finally fade, and therefore the sum of these influences is that all the conditions necessary for the sky to be shining were never present.

We cannot see the light coming from galaxies or stars separated from us at different distances at the same time. Either the light from distant stars is still on its way to us, or the light from the stars near us becomes dim and becomes dark when the distant light finally reaches us.