Fire in space

[AnnaG]

I recently had a discussion about fire and how temperature has an effect upon it. The idea of fire in space popped into the discussion (I think because the one I was discussing the issue with thought he could catch me up somehow). Fire is simply hot gases and sometimes happens when a substance oxidizes depending upon the chemical reaction. Water can also oxidize things without adding heat.
Oxidation happens when the loss of electrons occurs. The opposite event is called "reduction". Oxidizers are substances like oxygen, sulfur, halogens, and fluorine. If something oxidizes in space it carries its own fuel and oxidant. Anyway, when the loss of electrons occurs, energy is given off, and if the activity is rapid enough it will appear as "fire" (hot gases).
It is the same in outer space as it is in an atmosphere. The difference being that the substance in space carries its own oxidizing agent and the reaction is exothermic. In atmosphere the process can be sped up by adding a heat source.

Thermodynamics - Wikipedia, the free encyclopedia

Have I missed anything?

 

[Dexter Sinister]

No, I don't think you've missed anything. But just for interest: Gravity can affect what the flames look like, because without it there's nothing to drive convection. A propane torch flame inside an orbiting shuttle probably wouldn't look much different (though I don't think it's been tried), because it uses pressurized fuel and creates its own convection. A candle flame in the shuttle (which HAS been tried) looks very different, because the only way for oxygen to get to it is by diffusion. You don't get that pretty conical yellow flame with the blue center, you get a little orange ball.

 

[AnnaG]

No, I don't think you've missed anything. But just for interest: Gravity can affect what the flames look like, because without it there's nothing to drive convection. A propane torch flame inside an orbiting shuttle probably wouldn't look much different (though I don't think it's been tried), because it uses pressurized fuel and creates its own convection. A candle flame in the shuttle (which HAS been tried) looks very different, because the only way for oxygen to get to it is by diffusion. You don't get that pretty conical yellow flame with the blue center, you get a little orange ball.

So tails of comets and the like are simply the sunlit sections of the balls? That is interesting.

 

[Dexter Sinister]

Comet tails are dust and gas, there's no combustion going on, but yes, they're visible only by reflected sunlight, they don't generate light of their own.

 

[AnnaG]

Comet tails are dust and gas, there's no combustion going on, but yes, they're visible only by reflected sunlight, they don't generate light of their own.

Ah ok. I was having trouble with the idea just after I posted. lol