Mystery #1Tier 1Earth / space

Why do we have day and night?

Every day the Sun seems to rise, cross the sky and set, as if it's travelling around us. But the Sun isn't circling the Earth. So what's really turning day into night and back again?

Earth seen from space with the day–night line (terminator) crossing it — Photo: NASA (ISS) · Public domain · via Wikimedia Commons

Your guess

What's your hunch — what actually causes day and night?

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