Animation of the proton-proton III chain reaction, one of the nuclear reactions that powers the Sun by converting hydrogen to helium. In the Sun's core, it is hot and dense enough that protons (red) can collide and fuse, forming a diproton. One proton then undergoes beta decay, turning into a neutron (yellow) and emitting a positron (orange star) and a neutrino (pink), forming a deuterium nucleus (hydrogen-2). Another proton then fuses with this, forming helium-3 and emitting a gamma ray (yellow wave). This then collides with a helium-4 nucleus, forming beryllium-7 and another gamma ray. Another proton collides, forming boron-8 and emitting a gamma ray, before one of the protons beta decays, emitting another positron and neutrino and forming beryllium-8. The beryllium-8 then splits into two helium-4 nuclei. This p-p III branch produces 0.11% of the Sun's energy. See clips K003/3971 for the dominant p-p I branch, and K003/4575 for the p-p II branch.