In weightlessness impossible to cry

Crying in outer space is physically impossible - no tears will flow from my eyes, literally, and remain inside as liquid balls, burning eyes and disturbing to see. Astronauts on such a case there is a special "sovochki", by which they get rid of excess fluid in the eyes.

According to the theory of evolution tears are a calming effect, so the cause of pain should not be. However, in zero gravity tears may have a negative effect on vision. One explanation for this - that the liquid during a prolonged stay in microgravity conditions inside the head, as it were "displaced". It is possible that gives us the space is too small amount of liquid for wetting the eye, and they are long dry, whereby moisture, particularly in the form of a ball, falling on the cornea, soothes and irritating it.

via factroom.ru