Look up in the sky. What can you see? You can see the sun. At night, you can see the moon and many many stars. The moon is nearer us than the sun. The sun is much farther. The moon looks almost as large as the sun. But the sun is really larger. The sun is a star. It is a big ball of fire. It sends out light. The moon is a satellite(卫星). It doesn't send out light. There isn't any air on the moon. There are no trees or water on the moon. It's very hot in the day time, but at night it can be -129℃ .
