Why is the sky dark at night?

Answer 1

By at least one of these two reasons:

-the speed of light is not infinite (true)

the Universe is finite(?)

Every single point in the sky would be occupied by a single star if the universe were infinite. Moreover, if the speed of light were infinite, all of these stars' light would reach Earth simultaneously, making the nights appear brighter than the days we actually experience.

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Answer 2

Ian Aitchison

The sky is dark at night because the Earth's atmosphere scatters sunlight, making it appear blue during the day. At night, when the sun is no longer directly illuminating the atmosphere, there is no scattered light reaching our eyes, causing the sky to appear dark. Additionally, distant stars and galaxies emit light, but their light is not sufficient to fully illuminate the sky, resulting in darkness. This phenomenon is known as Olbers' paradox.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.