If you watch the sky about an hour after the sun goes down, you may see some "moving stars"．But they're not real stars.They are man­made satellites.And the biggest of all is the International Space Station (ISS国际空间站)．

　　From now until July is the best season to watch the ISS flying over the earth, and people can see it just with their eyes.The ISS is the biggest man­made satellite because scientists want to live on it.They think that the best way to learn more about space is to live there.

　　When the space station is finished, it will be like a city in space.People will stay and study there with many of the things they have at home.Laboratories, living rooms and power stations are being built.

　　The ISS is the most ambitious and expensive space program ever.Billions of dollars are being spent on it every year.Scientists hope that the ISS will be a stepping­stone for future space exploration."The ISS will help us better understand the human body, explore space and study the earth.It can help us make life on the earth better，" said Kathryn Clark, an ISS scientist.

　　China is not an ISS country, but it has helped with some of the experiments.China sent some rice up to the ISS to find out what space would do to it.

The ISS is not finished yet.More than 100 parts need to be put on.Scientists hope it will be finished as soon as possible. After it's finished, more than 90% of the world's population will be able to see the Space Station.So keep looking up, and maybe you'll see it get bigger.