The occurance of day and night
1. The rotation of the Earth on its axis takes place at all times. However, the position of the Sun is always fixed.
2. At any one time,
a) half of the Earth is facing the Sun. This part of the Earth receives sunlight and experiences day.
b) half of the Earth is facing away from the Sun. This part of the Earth does not receive sunlight and, therefore, is in darkness.
3. The Earth takes 24 hours to complete one rotation. during every 24 hours :
a) half of the Earth experiences day
b) half of the Earth experiences night.