spaceSpace and Physics

What Happens When You Light A Candle In Space?


Tom Hale

Tom is a writer in London with a Master's degree in Journalism whose editorial work covers anything from health and the environment to technology and archaeology.

Senior Journalist

3892 What Happens When You Light A Candle In Space?
cbransto/Flickr. (CC BY 2.0)

We’ve all seen movies that feature a fire in the depths of space, most notably in the 2013 film Gravity where – along with George Clooney smouldering away – we see a fire break out on their space station.

But how would a fire actually behave in microgravity? Fortunately, NASA scientists have long been pondering that themselves.


Since 2009, researchers onboard the International Space Station have been conducting experiment FLEX (Flame Extinguishment Experiment) which sought to find out how fire behaves in space and, more importantly, how to extinguish it.

When you light a candle, it forms that classic teardrop shape. However, that’s only because of gravity. When the oxygen is consumed by the fire, the hotter air rises and the cooler uncombusted air sinks to the bottom. But without gravity, there’s no separation between lighter and heavier air, so the fire burns in all directions equally, causing a slow-burning globe of combustion.

Weirdest of all, FLEX found that combustion can happen without any visible flames.

Check out this episode of DNews which shows even more weird and wonderful demonstrations of fire in space.




Main image credit: cbransto/Flickr. (CC BY 2.0)


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