Image by: Matthew Bowden www.digitallyrefreshing.com
Before you see the answer, think about this for a while? Assume that you are in space, and you are surrounded by an earth-like atmosphere – i.e. 20% oxygen and the rest mostly nitrogen. Would a candle burn? Why, or why not?
The Straight Dope has an answer. Apparently, astronauts in the space shuttle did an experiment to check precisely this:
The space shuttle astronauts brought a couple along on a mission last summer and lit them inside a sealed chamber having an earth-type atmosphere. (This is not something you would want to do in the open space shuttle cabin, where for obvious reasons an exposed flame is on a par with leaving the front door open.) One candle burned for about two minutes, the other for 20 seconds. Then–here’s the vindication you’ve been waiting for–they snuffed. The flames were weak, spherical, and pure blue.
As you realized and your earthist friends obviously didn’t, in a zero-gravity environment you don’t have convection. Convection is the familiar process whereby heated air over a candle flame rises, carrying smoke and waste gases with it. Cool, oxygen-rich air rushes in to replace the departing warm air and in the process keeps the flame going. Convection works in normal gravity because warm air is less dense and thus lighter than cool air and so rises above it. But in a weightless environment the exhaust gases basically hang around the candle flame until all the oxygen in the immediate vicinity is exhausted, at which point the flame goes out.
The full article has more interesting things to say on this topic.