There are many people in the world now. There will be a lot more people next century. Theearth will be very crowded and there will be a little room for each person. Maybe there will only be standing room on the earth 600 years later. That will be a very serious problem.So man is thinking of a way to solve the problem.The moon is the satellite of the earth. Maybe man will go to stayon the moon one day. But there is no air, no plants, no life there. So scientists are doing experiment in many ways. They have tosolve many problems before man can live on the moon. I'm sure our dream will come true in the next century.