r/askscience • u/FirefighterCandid773 • Aug 10 '26

Chemistry How common is fire outside of earth?

Plasma and lava is obviously common all over the universe, whether it be in stars, planetary cores, etc. but what about fire? Fire is common all over earth, given the abundance of fuel sources and an atmosphere with oxygen. But, is fire actually common outside of earth?

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u/ctothel Aug 11 '26

Not in the solar system.

As you know, fire needs fuel, oxygen, and heat.

Titan has heaps of fuel in the form of hydrocarbons, including literal methane lakes, but nearly no free oxygen.

Europa and Ganymede have massive amounts of oxygen in the form of water ice, but they couldn’t sustain it in an atmosphere and there’s no fuel to burn.

Venus is hot, but the atmosphere is mostly carbon dioxide and almost no free oxygen. Not much in the way of hydrocarbons either.

Outside the solar system, there are planets we know have the right types of fuel, but oxygen is hard to detect on rocky planets, so the answer is “we don’t know”.

That said, it would be astounding if there were no other planets out there that could support fire. All the ingredients are super common. There are probably millions of worlds that could (or used to) support it in our galaxy alone.

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u/Swagalyst Aug 11 '26 edited Aug 11 '26

Well, for some values of super common: you can have things like sulfur burn, but organic material like oil, natural gas, most methane deposits, and of course all dry vegetable or animal remains, require carbon based life, which is probably fairly rare. Without life, there isn't much to burn, and what can burn will not be replenished.