In the absence of gravity, flames will tend to be spherical, as shown in this NASA experiment

In the absence of gravity, flames will tend to be spherical, as shown in this NASA experiment

Great balls of fire: How flames behave in space

It’s a process called molecular diffusion, and it produces spherical flames that are different from their Earthly counterparts in more ways than one. Not only do they burn much slower and for longer periods of time, but they also survive on less oxygen and clock in at less than 900 degrees Fahrenheit — a fraction of the heat given off by most terrestrial flames.

And yet, there’s still much scientists don’t understand about how fire operates in microgravity. Are certain materials more flammable than others? What’s the best way to extinguish a rogue flame?

These questions are critical for the safety of astronauts already living and working in the International Space Station (ISS), and will only become more important as humans prepare for longer space voyages. Luckily, NASA scientists are on the case.

https://www.astronomy.com/science/great-balls-of-fire-how-flames-behave-in-space/