Ronna/Alamy
Garry Trethewey
Cherryville, South Australia
A candle flame isn’t a thing, but a process. Burning heats air, which expands and becomes less dense. Because of gravity, the non-heated air around it falls, but in common parlance, we say the hot air rises. That creates a flow, bringing fresh oxygen to support combustion.
Without gravity, or a fan to maintain gas flow, the candle flame would surround itself with a sphere of oxygen-free burnt gas, and the process would end in a small fraction of a second.
Richard Klingbiel
Friday Harbor, Washington, US
A flame in zero gravity would be spherical.…
