Internal structure

The Sun is composed almost entirely of hydrogen (74%) and helium (25%), with other trace elements. The innermost layer of the Sun is the core, where the nuclear fusion reactions are taking place. Outside that is the radiative zone, where photons of gamma radiation created in the core are emitted and absorbed by hydrogen atoms. A single photon can take 100,000 years to finally get through the radiative zone. Outside the radiative zone is the convective zone, where bubbles of plasma rise and fall like a lava lamp.