Radiative Zone

Radiation is a very important aspect of the Sun.  It is the main process through which the Sun transfers its energy out into space.  The radiative zone of the solar interior is characterized by the process of radiation.

The energy made in the core is in the form of photons, more specifically in gamma rays, when it first begins its journey outward. This energy is changed into less energetic photons as it moves through the radiative zone. This is good for us because gamma rays are very dangerous to humans!

In radiation, energy diffuses out from the core through these photons. They move very quickly (at the speed of light!), but they also bounce off so many other particles that it takes hundreds of thousands of years for them to get through the radiative zone.  All of the bouncing off of other particles sends the photons flying off in all directions, instead of taking a straight path outward.  This is called a random walk.  You can see this in the illustration to the right.

Radiation moving out from this part of the Sun gets absorbed more readily, reducing the amount that actually makes its way out of the Sun.  This makes the gas unstable, and leads to convection.  This process is outlined in the section on the convective zone.

This is a diagram of the layers of the Sun.  Here you can see the radiative zone is directly outside of the core.