the sun

[fatgaz]

how can the sun be a ball of fire if theres no oxygen in the universe?

[scotstone]

There is oxygen in the universe or we wouldn't be here. However it is not used by the sun as the sun doesn't burn. The sun produces heat by nuclear reactions deep within its core and by nuclear fusion converts hydrogen into helium.

[CT]

The sun is not fire in the sense that you would think of it on earth. The fusion reactions in the core produce the energy ( not chemical interactions like fire).

[fo3nix]

as the above say, it's not a ball of fire at all. it is in fact a plasma. many, many things in the universe are plasmas.

[fo3nix]

I didn't really give much information on what a plasma was, sorry. This link should help a bit:

http://en.wikipedia.org/wiki/Plasma_%28physics%29