Why is the sky blue during the day and black during the night?
At night there is no much light coming in frmo the other stars
so itis dark. During the day the dust and molecules in our air
scatter the light from the sun. The size of the dust and molecules
is just the right size to scatter the blue light and lets the red
pass through. This is why the sky at at sun set is redder and the
daytime sky is blue.