From Newsgroup: sci.astro.amateur
https://www.youtube.com/watch?v=LyXqDqB3ikc
On Earth, due to gravity, when a candle burns, hot air rises and cold air falls, so the flame takes on a cone shape. In space, due to zero gravity, the gas spreads in all directions, so the flame takes on a spherical shape.
So, if the power goes out completely on their SS, they can just light a candle! Efye
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