The radiation zone refers to the solar radius of 0.25 ~ 0.86. The radius of the sun is the solar radiation area, which contains all kinds of electromagnetic radiation and particle flow. The process of radiation transmission from the inside to the outside is a process of being absorbed by matter many times and re-emitted.

On the journey from nuclear reaction area to the surface of the sun, energy radiates outward in the form of X-rays, extreme ultraviolet rays, ultraviolet rays and finally visible light. The sun is an inexhaustible source of energy.

Energy transfer mode in radiation area

The radiation zone starts from the core edge and then extends outward by 55% of the solar radius. In this region, photons transmit the energy generated by the core to the outside. After the photon is generated, it propagates about 1 micron (one millionth of a meter) and is absorbed by gas molecules. Gas molecules are heated after absorbing photons, and then emit a photon with the same wavelength.

The re-released photon travels one micron, is absorbed by another gas molecule, and so on. Every interaction between photons and gas molecules takes some time. In this region, each photon must undergo about 1025 times of absorption and re-emission before reaching the surface, so the time delay between photon generation in the core and its transmission to the surface of the sun is quite large.