People, animals and plants live on the Earth. The Earth goes around the sun once every year to give us different seasons. The Earth also turns around itself once every twenty­four hours. This causes (引起) day and night on the Earth.

The moon moves around the Earth. The sun is bigger than the moon. But the moon looks bigger than the sun, because it's nearer (较近) to the Earth. The sun is very bright. It gives out (散发) very strong light. The moon looks quite bright too. But it doesn't give out any light at all.

The Earth