In the universe, as we know, there is the sun, the moon, the earth and many stars. Through our geography lessons, we know the earth goes round the sun, and the moon goes round the earth. We have day and night because the earth keeps turning all the time. When our part of the earth turns to the sun, it is day. When our part of the earth turns away from the sun, it is night.
Just because the moon is closer to the earth than the sun, it looks much bigger than the sun. Big things look smaller when they are farther, and small things look bigger when they are nearer.
The sun is bright enough to give out very strong light. The moon can't give out any light at all, but it looks quite bright too. Why? In fact, the light from the moon comes from the sun. The moon looks much bigger and brighter than the stars. But actually(事实上) the stars are much bigger and brighter than the moon. They look smaller than the moon also because they are farther away from the earth.
There are still many other planets in the universe. All of them move round the sun. But of all these planets, only on the earth are there living things and people can only live on the earth too. At 9:00 am, on October 15th, 2003, Chinese astronaut Yang Liwei was sent into space. He stayed there for 21 hours. It was the first time for Chinese to get into space.
