In the absence of gravity surface tension dominates the physics of fluids
Here, in an image taken on the International Space Station, surface tension causes water to extend from a metal loop as if it were stirred by an invisible spoon.
This stirring effect was created by using a flashlight to unevenly heat the water. The resulting temperature difference induced an imbalance in the surface tension, causing the fluid to rotate.
Such surface-tension-triggered movement, called Marangoni convection, is less obvious on Earth, but can be seen in environments such as cooling puddles of molten steel.
The International Space Station may still be under construction, but microgravity research has been under way for decades. Here is a round-up of some of the most notable experiments.
