Well, as a matter of fact the sun is shining at night, but we can’t see it. The Earth, which is rotating in space, turns completely round once every twenty-four hours. In the course of this rotation each part of the glob will be facing the sun for a certain amount of time. It is this time which we call ‘day’. When the part of the globe where we live is facing away from the sun, and we cannot see its light, we call the time ‘night’. So, when it is day for you, it is night for many other people, far away in other lands.