Symbols of Nature (Day and Night are Gift from Allah)

In our Solar System Sun is centre and our Earth and Moon even other 9 Planets of our solar system are revolving aroud sun, they are also revolving around themselves also.

Why is there Day and Night?

Clearly, when you see the Sun shining in the sky, it is day, and when you don't it is night. So the real question is "why is the Sun in the sky at some times and not at others?" We can see that the Sun seems to move across the sky starting in the east in the morning, moving toward the south at noon, and then toward the west as the day ends. How does this happen?
Long ago, people believed many weird things about the Sun and how it traveled across the sky. The ancient Greeks believed that the Sun rode across the sky in a chariot drawn by four white horses driven by the god Heleius! These days, we know that the Sun appears to move across the sky because the Earth rotates on its axis.
So how does the turning of the Earth lead to the Sun's motion across the sky? It is easy to see this if you shine a bright light on the side of a globe in a darkened room. Find where you live on the globe. Now slowly spin the globe on its axis so that if you look down on the north pole, it is rotating counterclockwise. Watch what happens to the place where you live. Do you see that it is sometimes pointed toward the light (which represents the Sun) and sometimes away from the light?
Simply Day nad Night are grace and gift of Allah for all creature on Earth, sleep time starts at night and it is very useful to sleep at night and there are many gangers for our health if we do not sleep in time in night.