Why is it dark at nigth?

Answer 1

I can think of two powerful reasons:

-- Because "night" (notice the spelling) is the name we give to the part of the daily

cycle when it's dark. If it were not dark, then it would not be night.

-- Because at night, the biggest, brightest, cheapest, most dependable source of light,

and the one that's easiest and most convenient for us to use most of the time, is gone.

That's the sun.