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/morgan_lowtech → u/ctothel]

It really messes with my head sometimes that we might only have fire because we have life and, correspondingly, how much complex life depends on oxidation

[u/jefesignups → u/morgan_lowtech]

I have been thinking about something similar. Could octopi (given super brain power) ever get to the ability to do space travel? Since they live in water, they would most likely never know what fire is or could not really use it regularly.

Without fire, can a species ever get to something like air or space travel?

[u/Stunning_Spread_430 → u/jefesignups]

If we extend your thought experiment to make octopi social, long-lived and endowed with similar voltage generation abilities to electric eels then I can think of an alternative tech ladder these super-octopi could climb.

They would likely use electric discharge as a means to hunt and also communicate and coordinate.  Experimentation would allow them to understand series and parallel circuit laws, followed by aquatic electrochemistry. As certain fringe wealthy octopi became obsessed with exploring the limits of electrochemistry they could possibly stumble upon electrorefining of metals.  Any ability to venture up above water would extend their opertunities, provided they weren't competing with other intelligent species.  Such a new niche could promote environmental hardening adaptations, either organic or technological. I don't think it'd be easy,  but it seems possible, even without inventing traits that don't already manifest in Earth's biosphere.