Fire seems intrinsically linked to life on Earth. The fires of the Earth’s molten core formed the land we live on, forests are at their healthiest when they burn in a controlled manner to make way for new life, and even the legendary R&B group Earth, Wind & Fire paid homage to the stuff. In fact, Earth is the only place we know of where fire occurs. That’s because fire requires three things to exist: heat, oxygen, and combustible material. This “fire triangle” is only possible on Earth, as far as we know, because of the planet’s high levels of free oxygen. Travel to other planets and moons in the solar system, and there isn’t enough (or any) oxygen for fire to exist. As for the sun, which some people imagine as a giant ball of fire, it’s actually a giant collection of gas that glows thanks to the complex nuclear fusion occurring in its core.
While fire may not exist in any other place in the solar system (as far as we’re aware), that doesn’t mean humans can’t export the stuff. NASA has experimented with fire in microgravity for more than a decade — both to discover its behavior and also design fire-resistant space material. Turns out fire in microgravity behaves much differently, appearing more sluggish (likely due to low oxygen) and forming strange, orb-like flames. So while it’s not impossible for fire to exist beyond the confines of Earth, it’ll need a lot of help from future astronauts to export it to the moon, Mars, and beyond.