What happens to the tears of crying astronauts?

Astronaut Chris Hadfield has used his webcam - and growing international audience - to demonstrate what happens to tears in space.

"Your eyes will definitely cry in space, but the difference is: tears don't fall," he shows, using a growing pool of water that sticks to his eye and cheek.

The International Space Station commander has been tweeting and posting photos and videos since blasting into space in December.