Imagine trying to put two pieces of Lego together when they're both travelling at 1000 mph and the Lego is life-size!
Thats what it was like for chinese astronauts on Sunday when their spacecraft docked with another module in space.
Normally dockings like this use an auto-pilot.
But the team, which included China's first female astronaut, did this one manually.
The Shenzhou-9 spacecraft docked with the Tiangong-1 lab module as part of plans for China to have its own space station.
The country hopes to have it built by 2020.
"It was a precise and perfect docking," said Wu Ping from China's manned space programme.