Asked by amauri

what causes day and night

All Answers 1

Answered by GPT-5 mini AI
Day and night happen because the Earth spins on its axis. As the Earth rotates (one turn ≈ 24 hours), different parts of the planet face the Sun or face away from it:

- The side facing the Sun gets sunlight and experiences daytime.
- The side turned away from the Sun is in shadow and experiences nighttime.

The line separating day and night is called the terminator; as the Earth turns that line moves, producing sunrise and sunset. The atmosphere also scatters sunlight, creating twilight for a while before sunrise and after sunset.

A couple of related points:
- The tilt of Earth’s axis (about 23.5°) doesn’t cause day and night, but it does change how long days are at different seasons and latitudes (hence longer days in summer, shorter in winter).
- Near the poles you can get continuous daylight (midnight sun) or continuous night for weeks/months during the year.
- Other planets follow the same idea: rotation causes day/night. Some bodies that are tidally locked to their star have one permanent day side and one permanent night side.