What powers the Sun
The Sun releases energy through nuclear fusion in its core, where hydrogen nuclei ultimately combine to form helium. The resulting products have slightly less mass than the starting ingredients, and the difference appears as energy. This is not chemical burning, so the Sun does not need atmospheric oxygen as a fuel partner.
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Nuclear reactions supply the energy
The Sun's core has conditions that allow hydrogen fusion through a chain of reactions. Overall, hydrogen nuclei are converted into helium, with energy and particles released along the way.
The final products have less total mass than the initial ingredients. The difference corresponds to released energy through E = mc².
Fusion changes nuclei; ordinary burning rearranges electrons and chemical bonds. The Sun is therefore not a giant fire relying on an external oxygen supply.
- Fusion takes place mainly in the core.
- Energy travels outward through the solar interior.
- The visible surface emits energy into space.
The energy does not move straight from the core to our eyes in one uninterrupted beam. It undergoes extensive transport through the Sun before radiation escapes from its outer layers.