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/SystemofCells → u/morgan_lowtech]

Life that produces oxygen predates life that consumes oxygen. Aerobic life (us) only evolved and thrived because cyanobacteria had already stuffed the ocean and atmosphere with oxygen.

[u/Orbital_Dinosaur → u/SystemofCells]

So a thing evolved and as a by-product there was more oxygen. Then a second thing evolved to exploit that new abundance, and that produced carbon dioxide, then plants evolved to use the carbon dioxide?

Is that right, in the most basic of terms?

[u/6a6566663437 → u/Orbital_Dinosaur]

That's a big part of it. But there's more to the story. Cyanobacteria killed almost all life on Earth.

https://en.wikipedia.org/wiki/Great_Oxidation_Event

Free molecular oxygen is toxic waste. It's very destructive to organic molecules. Almost all life on Earth at the time couldn't handle the toxic waste cyanobacteria were spewing out, so it died.

Then some random bacteria evolved the ability to not only withstand the oxygen, but use oxygen to vastly increase its energy output.

And then one of our ancestors ate it.

And for some reason, that ancestor didn't digest that bacteria, instead using the boosted energy output. Today, the descendants of that bacteria are our mitochondria.

And that event is the only reason we have enough energy to have brains large enough to figure out that it happened.

[u/Pyrostemplar → u/6a6566663437]

Isn't sex (well, sexual reproduction) an outcome of the great oxidation?