How are days and nights caused on Earth?
Days and nights on Earth are caused by the rotation of the Earth on its axis. The Earth rotates once on its axis approximately every 24 hours, which creates a cycle of alternating periods of daylight and darkness.
As the Earth rotates, half of it is facing towards the Sun, experiencing daylight, while the other half is facing away from the Sun, experiencing darkness or night. The line that separates the illuminated half of the Earth from the dark half is called the terminator. The terminator is constantly moving due to the Earth’s rotation, causing the length of daylight and darkness to change throughout the year.