A theoretical model of the Sun shows how energy gets from its center to its surface

• Hydrogen fusion takes place in a core extending from the Sun’s center to about 0.25 solar radius

• The core is surrounded by a radiative zone extending to about 0.71 solar radius

  • In this zone, energy travels outward through radiative diffusion

• The radiative zone is surrounded by a rather opaque convective zone of gas at relatively low temperature and pressure

  • In this zone, energy travels outward primarily through convection