Why does Earth have day and night?
Follow one place as Earth turns. The Sun keeps shining, even when that place is in darkness.
Original interactive diagram. Sun, Earth and distance are not to scale. The tilted axis is shown schematically; coastlines are approximate.
What takes a place from daylight into darkness?
Take a guess, then try the experiment. No score, and nothing is saved.
Turn Earth. What changes?
The orange dot follows one place on the equator. The sunlight stays on the left as the planet turns underneath it.
Noon · The marked place is in daylight.
Use the slider, arrow keys or stage buttons. One illustrated day plays in 12 seconds; motion starts only when you choose Play.
The place moves; the light keeps coming
As Earth rotates, the marked place moves across the boundary between day and night. On the night side, Earth itself blocks direct sunlight from reaching that place. The Moon does not cause everyday night.
The dot sometimes passes behind the globe from our viewpoint. It still exists there: the text tells you whether it is in daylight or darkness.
Does every place get exactly 12 hours of daylight?
No. Daylight duration changes with latitude and season because Earth’s axis is tilted. This simplified equatorial example holds the Sun’s direction fixed and shows a 24-hour cycle with evenly spaced stages. It ignores twilight, atmospheric refraction and Earth’s orbital progress; it is not a sunrise forecast or a civil clock.
ESO Supernova: what causes day and night? · NASA: rotation, revolution and solar days · Coastline data: Natural Earth
If Earth keeps turning, why do we need time zones?
Different places face the Sun at different moments. Our clock labels help us coordinate.
Discover why time zones exist →Try the live day & night globe →