A mean solar day is about 24 hours. Earth rotates while also moving along its orbit, so a day measured against the Sun differs slightly from a rotation measured against distant stars. Near the poles, daylight or darkness can last far longer than one day.
Space · Discover & try
What causes day and night?
Reading level 5 of 5 · AdvancedChange
Word help
Rotation
Spinning around an axis.
Axis
An imaginary line through the poles around which Earth turns.
Orbit
A path around another body.
Watch · Try · Explain
See how it works
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A simplified rotating-Earth model. Globe markings and sizes are illustrative; no local sunrise times are predicted.
What to look for
- Follow one marked place, rather than the whole globe.
- Compare the lit and unlit sides.
- Distinguish a daily turn from a yearly orbit.
Explain what you noticed
What mainly causes the everyday change between day and night?
Keep this idea: Earth’s rotation carries places into and out of sunlight.
Follow the sources
Source material checked 2026-10-28. Explanations and activities by Nepedia. Agency source links do not imply endorsement.
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