Day and night — Astronomy, 7–10 years
Earth turns like a slowly spinning ball. The side facing the Sun has daylight, while the side turned away has night.
A turning Earth
Earth spins around an invisible line through its north and south poles. As it turns, your place takes its turn facing the Sun and then turns away. Sunlight does not follow us around Earth: our turning makes day and night.
Why does it get dark?
Long ago, people could see the Sun cross the sky, so it was easy to imagine that the Sun moved around us. That idea leaves a puzzle: why do distant places have daytime when we have night? A spinning Earth explains both views with one simple movement.
A torch and a ball
Place a small sticker on a ball and shine a torch at it from one side. The sticker is lit, so it represents daytime. Turn the ball slowly: when the sticker moves to the dark side, it represents night. One complete turn brings the sticker back to daylight.
The Sun is not going round us
A common mistake is to say that the Sun rises, travels over us, and goes around Earth each day. That is a reasonable guess because the Sun really does appear to move across our sky. The better explanation is that Earth turns, carrying us through sunlight and then shadow.
Planning a day
Day and night help people plan when to work, sleep, travel, and watch the sky. Clock times are different around Earth because places turn into sunlight at different moments. Spacecraft teams also use this pattern when they plan signals and observations from Earth.
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