Canadian Space Agency astronaut Chris Hadfield demonstrates the physics of tears in space. Watch on YouTube





Is there anything Canadian astronaut Chris Hadfield can't do? He's the commander of the International Space Station, a guitar-strumming space troubadour, a prolific orbital photographer and a frequent commentator about life in space. Hadfield seems to do it all, but apparently there's at least one thing he can't do — namely, shed a tear in zero gravity.

Hadfield demonstrated why there's no crying in space last week, in an instructional video from the space station. He squirted water from a bottle into his eye, and then showed how the liquid just kept piling up on his face.

"If you keep crying, you just end up with a bigger and bigger ball of water in your eye," he said, "until eventually it crosses across your nose and gets into your other eye, or evaporates, or maybe spreads over your cheek — or you grab a towel and dry it off. So, yes, I've gotten things in my eye. Your eyes will definitely cry in space. But the big difference is, tears don't fall."

"Tears Don't Fall" ... that sounds like a great title for Hadfield's next orbital ballad.

For more about the "no crying in space" phenomenon, check out The Atlantic's detailed explanation from January. And for more fun facts from Hadfield, watch his video guides to brushing your teeth in zero-G, shaving in space, how to clean up a space spill, and how to clip your fingernails on the space station.

More about life in space:

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.