You know that days and nights are not of equal duration. At times days are longer than nights, while at other times nights are longer than days. This is because of the inclined axis of thee earth. Had the axis been perpendicular to the plane of the orbit, then days and nights would have been of equal length all over the world and the rays of the sun would have fallen in the same manner at one particular place.
But it has been observed that in the summer season in the Northern Hemisphere the days are long and the nights are short and contrary to this, in the winter season, the nights are long and the days are short.
Both dawn and dusk are a period of diffused or refracted light that the earth receives from the sun when it is still below the horizon. With the rotation of the earth when the same place reaches a position just opposite to what it was as noon, i.e. at its farthest position forms the sun, it is said to have midnight.
The earth moves from west to east. It is because of this movement or rotation that the sun, the moon and the stars appear to us as if they move round the earth from east to west. This can be compared to the feeling we have when we are in a moving car. The objects outside trees, electric poles, houses etc. seem to be moving in the opposite direction. Actually they are still and instead we are moving with the car.