Why we have day and night

Why does the Sun disappear every evening?

Imagine you wake up in a sunny morning, then play, then it gets dark and you go to bed.

Does the Sun move around us, or do we move? Here is our home, planet Earth.

The Sun is a giant, glowing star. It shines light in every direction, all the time.

Earth is a ball, so sunlight can only reach one half at a time. The half facing the Sun has daytime. The half facing away is in shadow, so it has night.

• Sun lights one half only

Here is the big secret. Earth spins around, like a top, once every day.

Earth spins all the way around in twenty four hours. That is exactly one day.

• One spin = 24 hours

As Earth turns, your town slowly moves from the lit side into the shadow. That is sunset.

So the Sun only seems to move across the sky. Really, we are the ones turning.

It is like a carousel. Standing still, you think the world moves, but you are the one spinning.

Try it at home. Shine a torch on a ball in a dark room, then turn the ball.

• Turn ball = day to night

When it is day where you live, it is night on the other side of the world. Quick check to see what you remember. We have day and night because Earth spins, so each place faces the Sun, then turns away.

• Earth spins = day and night