Ever wonder what fire looks like in space?

Actually, this was shot in zero-g.  Still awesome.  Explanation after the jump --

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Explanation:
A flame is caused by heat excitation of electrons in a medium (normally the gases given off from what is burning). Hot air rises because it is less dense than the air around it, which causes the flame to rise upwards and slowly taper off. This upward movement of air also pulls in oxygen from underneath the flame to keep sustaining it.

However, in microgravity (which is what this picture is, not zero gravity) the air is the same density in all directions, so the heated air disperses evenly in all directions. The flame is smaller because the oxygen is not being pulled in by the air rising, but is only being diffused through the wick.

More importantly, the convection currents created by warm air rising speeds up the reaction and allows the flame to get hotter. this creates a secondary reaction (the yellow part of the flame) which can't happen if the hotter temperature isn't reached.