Besides airglow, what is the other natural component contributing to the faint light of a clear night sky?

Answer

The collective light from all stars and galaxies whose light has reached us.

One component contributing to the faint background luminescence is the collective light from all the stars and galaxies whose light has managed to reach us over cosmic time.

Besides airglow, what is the other natural component contributing to the faint light of a clear night sky?

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Why is it Dark at Night? - YouTube

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