Question

why does not sun shine at night

Answer 1

As Earth rotates around its axis, the part of the Earth facing towards sun, experience day. And the opposite part faces night.....

Answer 2

Sun always shines. It's seems not to shine because of the rotation of Earth. Which part of the earth is at the dark side there is night and the part towards the sun it's day. And one more tip that moon doesn't have the light of it's own. It reflects the light emitted by the sun