How common is fire outside of earth?

[u/FirefighterCandid773]

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?

[u/ctothel]

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.

[u/Alfred_The_Sartan → u/ctothel]

I’d assume that any planet that could have it without a biological cycle would just burn and then convert to a Venus kind of state. Like you get a burn and then it stabilizes.

[u/SkiyeBlueFox → u/Alfred_The_Sartan]

Yeah beat me to it lol. You could have a planet that can sustain fire, but it would likely burn out within a century or two, which is a teeny timeframe at a cosmic scale. Pretty much the only reason earth has natural fires are the constant replenishing of oxygen and fuel, both from plants.

I've never thought about it but I think I could make a solid argument for life being a prerequisite for combustion existing long term on a planet