The sun is powered by a hydrogen fusion reaction of a kind we cannot produce on Earth (for various reasons, having to do with thermodynamic conditions and timescale of operation). We compare our observations with what is predicted by theory and find good correspondence. Theories are never "proven"; they are either verifiable or not. Sometimes a good theory is displaced by a more elaborate or more accurate theory when fine details are examined.
The sun is powered by a hydrogen fusion reaction of a kind we cannot produce on Earth (for various reasons, having to do with thermodynamic conditions and timescale of operation). We compare our observations with what is predicted by theory and find good correspondence. Theories are never "proven"; they are either verifiable or not. Sometimes a good theory is displaced by a more elaborate or more accurate theory when fine details are examined.