You can cry in the zero gravity of space, but the tears won't stream down your face like they do on Earth. That's what astronaut Andrew Feustel discovered during a spacewalk in 2011. He wasn't actually weeping out of sadness -- his eye was watering because a small irritant had lodged there during a seven-hour repair mission outside the International Space Station. The tears "don't fall off of your eye, they kind of stay there," he said later, describing the "liquid ball" that clung to his eyeball.
Floating tears and other effects of crying in space:
- According to astronaut Ron Parise, "When the tears get big enough, they simply break free of the eye and float around."
- Tears don't hurt on Earth, but for some reason, the zero gravity of space can create a nasty case of dry eye. When moisture begins to well up on the cornea, the fluid buildup can sting.
- Space flights that last six months or longer can cause astronauts' eyes to change shape. The most common change was the flattening of the back of the eyeball.