On Earth, when we cry, our tears fall down our faces due to gravity. Gravity is the force that pulls objects toward the center of the Earth. This is why teardrops roll down our cheeks. The gravitational pull is strong enough to overcome the surface tension of the tears, causing them to fall.
In space, however, astronauts experience what we call microgravity. This means objects appear weightless and float freely. The International Space Station and everything in it, including the astronauts, are in a constant state of free fall around Earth. When astronauts cry in space, their tears don't fall down their faces. Instead, the tears form small blobs that stick to their eyes due to surface tension.
In the absence of gravity, surface tension becomes the dominant force acting on liquids like tears. Surface tension is caused by the cohesive forces between liquid molecules. These forces pull the surface molecules inward, creating a tendency to minimize the surface area. This is why liquids in space naturally form spherical droplets - a sphere has the minimum surface area for a given volume. When astronauts cry, their tears form blobs that cling to their eyes or skin rather than falling down.
Astronauts have to be careful with tears and other liquids in space. Since tears don't fall but instead form floating blobs, they can be uncomfortable and potentially hazardous. Floating tears could get into sensitive equipment or cause irritation if they float back into an astronaut's eyes or nose. To deal with tears, astronauts typically use tissues or towels to absorb the liquid before it floats away. Some astronauts have reported that the sensation of crying in space feels different because the tears accumulate and form a layer over their eyes rather than rolling down their cheeks.
To summarize what we've learned: Tears don't fall in space because there is no significant gravity to pull them downward. Instead, surface tension becomes the dominant force acting on the liquid tears. This causes tears to form spherical blobs that stick to the eye's surface rather than falling down the face. Astronauts must use tissues or towels to absorb their tears before they float away. This same principle applies to all liquids in space, which is why drinking and managing fluids requires special techniques in the microgravity environment.