A reaction called nuclear fusion turns hydrogen atoms into helium. The by-product of nuclear fusion in the Sun's core is an enormous quantity of energy that is released and that emanates outward toward the surface of the Sun then into the solar system way beyond it. Moreover, the Gama rays created in the core moves through the gases of Sun and it takes about a million years to make it to its surface as they crash into atoms. Throughout the travel it turns into visible light and infra red waves..The time period differs in dissimilar calculations. Others say it probably takes 20,000 years to get to the surface.