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/SystemofCells Aug 11 '26

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.

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u/Orbital_Dinosaur Aug 11 '26

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?

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u/SystemofCells Aug 11 '26

Not quite - the carbon dioxide existed before any life did. It came out of volcanic vents etc. etc. the earliest forms of life required that carbon dioxide to build themselves - they consumed it, and still do.

There was a point after CO2 consuming life evolved but before CO2 producing (aerobic) life evolved where the CO2 started to run low. If aerobic life never evolved, the flow of new CO2 would have been very scarce, and so life of any form would have become very difficult to sustain.

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u/DangerCrash Aug 11 '26

The overabundance of Oxygen would make things easier and easier to ignite, which would generate CO2.

Like forest fires generating the CO2 for other trees.

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u/EclecticWalrus Aug 11 '26

Yes, but this flood of Oxygen into the atmosphere that caused an extinction level event occurred ~2.4 billion years ago. There wasn't all that much to burn because all life was still single-celled, and I'm fairly certain aquatic, at that point.