If fire needs air to burn, but there's no air in space, what keeps the Sun burning?

[FunkyMonkee]

Updates

3 mo

Thank you all. Science is not a long suit for me and I didn't know that the Sun had gone fission.

[AviatorTom]

The Sun doesn't burn. The sun is a ball of nuclear fission, releasing huge amounts of energy across the entire electromagnetic spectrum as elements collide and physically change their properties into other elements.

[DryGermanGuy]

How about, after entering retirement, you apply for a course in nuclear physics at your local community college?

[FunkyMonkee]

Because I didn't know the answer to one question?

[DryGermanGuy]

You‘re generally on a bad footing with all sciences.

[AI Opinion]

I’m Advisor Smith. This is a great example of how everyday intuition can mislead us.

Fire on Earth is chemical combustion: fuel + oxygen → heat, light, smoke. That needs “air.”

The Sun isn’t burning in that way. It “burns” by nuclear fusion, not fire.

In the Sun’s core:
- Enormous gravity creates extreme pressure and temperature.
- Hydrogen nuclei are smashed together into helium.
- That process releases huge amounts of energy (light and heat).

No oxygen, no air—just plasma and nuclear reactions. So the Sun shines because of fusion, not ordinary fire.

[RavVid]

Nuclear fusion of course but I think you know that :)

[FunkyMonkee]

If I did, I wouldn't have asked.

[NathanDavis]

that ain't a fire... lmao

it's plasma

[NathanDavis]

another fun fact... lightning is also "plasma"

it might start like a big ass spark of electricity, but what we see is the ionized gas through the air... the lightning plasma

and if you've ever seen one of those kick-ass plasma torches... those are also gas + electricity, and not exactly "fire"

[Anonymous]

Fire is combustion. It requires a fuel (like wood), an oxidizer (oxygen from our air), and heat. The Sun does not use oxygen to create heat and light. It uses nuclear fusion

[Cidknee]

Its fusion.

[Cidknee]

It's fusion not fission. That's weaker. Fusion is contagious.