We all know what a candle looks like when we burn it. The blue at the bottom is the heavier and cooler fire. Because of gravity, the blue is at the bottom while the hotter and lighter fire is towards the top. On earth, fire burns up and around and spreads because of the oxygen that it has access to. In space, because there is no gravity and a very low concentration of oxygen, fire burns in spheres and spreads quickly based on where it can get the oxygen.
In the video below, fire in space is explained in further depth with baffling information about combustion as well.
Until next time,