Solar Fusion & Energy Transport: Physical Mechanisms

The Sun's long-lived power source is nuclear fusion in its core, primarily the proton–proton chain that converts hydrogen into helium.

High core temperatures give protons enough kinetic energy, aided by quantum tunneling, for fusion reactions to occur despite electrical repulsion.

Solar neutrino detectors measure particles produced directly by nuclear reactions in the core, while helioseismology checks the temperature-density structure predicted by solar models.