Fire On Exoplanets?
September 13, 2013 7:52 AM   Subscribe

How likely is it that fire (as in open flame) will exist on extra-solar planets?

Give the specific needs of fire: oxygen, heat, and fuel, what is the likelyhood of it being common on other planets (I know that we are still at the best guess stage with exoplanets, and I know that the universe is a big place, lots of possibilities etc.)

I'm specifically not talking about fusion, as it doesn't need oxygen, but open flame. Is it possible that fire exists in the same Goldilocks zone as our predictions on where we are most likely to find life? Or are the three components common enough that open flame is just going to be one of those things that exists everywhere?
posted by quin to Science & Nature (7 answers total) 5 users marked this as a favorite
Best answer: From Wikipedia's article "flame":

Other oxidizers besides oxygen can be used to produce a flame. Hydrogen burning in chlorine produces a flame and in the process emits gaseous hydrogen chloride (HCl) as the combustion product.[4] Another of many possible chemical combinations is hydrazine and nitrogen tetroxide which is hypergolic and commonly used in rocket engines. Fluoropolymers can be used to supply fluorine as an oxidizer of metallic fuels, e.g. in the magnesium/teflon/viton composition.
posted by tylerkaraszewski at 8:00 AM on September 13, 2013

It's highly likely. I imagine there are probably at least 100,000* exoplanets that are currently flaming as we speak. Just think of how many meteors are hitting planets in our unimaginably huge universe and the flames that result from that. Of course, if you mean exoplanets in our galaxy, then there might be someone who can come along with a better number for you.

*-Yes, that was pulled from my butt, but I would be very surprised if I was wrong.
posted by Grither at 8:02 AM on September 13, 2013

My quasi-half-assed-educated guess is that it'd be absolutely possible, but on the uncommon side. Heat, fuel, and oxidizers exist, but getting all three to exist in the same place and at the same time cuts your odds down some. (Although, my guess is based in part on the statement about "why you wouldn't be able to light the liquid methane on Titan" from this clip.)
posted by EmpressCallipygos at 8:09 AM on September 13, 2013

How does a flame behave under different gravities and air pressures? Say, is fire less likely to exist on a planet with a mass many times that of Earth's?
posted by popcassady at 8:15 AM on September 13, 2013

but getting all three to exist in the same place and at the same time cuts your odds down some.

I imagine you'd need to factor in the presence of other elements also. You may be able to ignite the match, but if you have the wrong amount of hydrogen in the atmosphere...
posted by popcassady at 8:21 AM on September 13, 2013

Best answer: They key to your question is actually, which exoplanets have life. Generally speaking, free oxygen in a planet's atmosphere quickly gets tied up in rocks. Earth has oxygen in its atmosphere because it has photosynthesizing life that give off oxygen faster than it can get bound up in chemical compounds in rocks and soil.

On Earth, after photosynthesis went on for a while, enough O2 built up to allow for the formation of a layer of ozone (O3), which is a very efficient ultraviolet absorber. With the ozone layer blocking the Sun's UV, dry land became safe for life, allowing plants and fungi and that sort of thing to evolve on land, which provides the fuel you need.

Lightning is a pretty common weather process on all the planets, so getting a spark to start a fire isn't hard.
posted by BrashTech at 9:18 AM on September 13, 2013 [7 favorites]

Came in to say what BrashTech said above. What you're asking is more or less whether life exists on exoplanets. There are other circumstances where open flames might be possible, but they're probably far less likely.

Consider: Mars is red, because iron is a common element (stellar fusion ends in iron) and free oxygen attacks iron to form rust. All of the free oxygen gets tied up because oxygen is very reactive and it rapidly oxidizes stuff. There wouldn't be any free oxygen on Earth either if it weren't for all that photosynthesis.

So no open flames are possible on Mars - at least, not until our giant rocket-mounted vats of blue-green algae Have I said too much? I've said too much...
posted by RedOrGreen at 9:49 AM on September 13, 2013 [2 favorites]

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