Why do we have day and night?

The sun is the star at the centre of our solar system. The nine planets orbit the sun.

As the earth orbits the sun it spins on its own axis.

Do you know how long it takes for the Earth to spin around once? That’s right! It takes 24 hours.

Don’t worry! The earth spins so slowly and smoothly we can’t feel it.

At any time half of the Earth faces the sun. This part has day. daynight The other half of the Earth faces away from the Sun. It receives no light. This part has night.

When it is day in Britain, on the other side of the world it is night.

Did you know? One day on Venus is the same as 117 Earth days. The mighty Jupiter whips around in just 9 hours and 57 minutes. One day on Mars is about the same as one day on Earth.

You should now be able to tell your partner the answer to these questions: Does the sun move ? How long does it take for the Earth to spin once? What is is like on Earth when that part spins away from the sun? Why is it day in Britain but night in Australia?

ACTIVITY This is Bleep-Bloop the alien. Don’t worry he’s quite friendly! Bleep-Bloop comes from a solar system far far away. When he visited Earth he couldn’t understand where the big ball of fire in the sky went each night. Write a letter to him explaining what the big ball of fire is and where it goes. You should use these words: Sun Earth spins axis solar system day night