Day and Night
Elementary School
Definition
The cycle of light and darkness caused by the Earth rotating once on its axis about every 24 hours. The side of Earth facing the Sun experiences day, while the side facing away experiences night.
Worked examples
When it is noon in New York (facing the Sun), it is midnight in Shanghai (facing away from the Sun).
Earth's rotation means opposite sides experience day and night at the same time.
A full rotation takes about 24 hours, so each location cycles through roughly 12 hours of daylight and 12 hours of darkness.
One complete spin on Earth's axis creates one full day-night cycle.
Common mistakes
- Day and night are caused by Earth orbiting around the Sun. → Day and night are caused by Earth rotating on its axis. Orbiting the Sun causes seasons (takes a year); rotation causes day and night (takes 24 hours).
- The Sun moves around the Earth, creating day when it is overhead and night when it moves away. → Earth rotates, so different parts face the Sun as it spins. The Sun stays in place; Earth's rotation makes it appear to rise and set.
- All places on Earth have exactly 12 hours of day and 12 hours of night every day. → Daylight length varies by season and latitude due to Earth's tilt. Equal day and night only occur at the equinoxes; tilt causes seasonal variation.
Where you'll use it next
You'll use this concept when learning about time zones, Earth's tilt and seasons, the Moon's phases, and how latitude affects daylight hours throughout the year.
See also
Reviewed by Pat Cheng, M.Ed. — StudyPug Curriculum Lead · Last updated June 6, 2026