In the universe, as we all know, there is the sun, the moon, the earth and a good many stars. Through our geography lessons, we know the earth goes around the sun, and the moon goes around 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 will look smaller when they are further, and small things also look bigger when they are nearer.
The sun is big enough to give out very strong light. The moon can't give 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 further away from the earth.
There are many other planets in the universe. But of all the planets, only on the earth there are living things and people can only live on the earth, too. But at 9:00 a.m. on October 15th，2003, Chinese pilot Yang Liwei was sent up to space. He stayed there for 21 hours. It was the first time for Chinese to get into space.
Can you imagine astronauts' everyday life in space? They also need to eat, 1 , exercise and relax. They do the same things as us, but they do2 differently.
On Earth, we put food on a plate and water in a glass. Gravity(重力) holds the food down and keeps the water in the glass. 3 there is almost no gravity in space, so food can float(漂浮) away, and astronauts must eat and drink4 .
Sleeping is very different in space. Some astronauts like to float in the air, but most like to be in a 5bag. They tie the bag to a wall 6 they won't float away at night. Exercise is very important in space. On Earth, your legs 7 your body, but in space, astronauts float. So they do not use their legs often. This is very 8their legs, so they must exercise for thirty minutes every day.
After a day's work, astronauts relax. They may listen to music, read, watch films, play games, or talk to their friends and families 9 the radio. Sometimes they just enjoy 10 in the air.
