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The Time Before Fire

This may come as a shock to you, but a billion years ago there was no fire on earth.

Fire itself is rapid oxidization. It's the energy released when oxygen atoms start combining with carbon and hydrogen atoms. So without oxygen in the air, nothing burns. Which means, there was a time before oxygen could be found on earth.

By roughly a billion years ago, simple forms of plant life called "eukaryotes" were already busily converting carbon dioxide into oxygen gas, just like their descendants do today. But before this process had been in place for a while, there wasn't enough oxygen in the air for things to burn.

Of all the planets, moons, asteroids, and comets in our solar system, the only place where you can actually start a fire is right here on earth. And even here, it's only been possible relatively recently.

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