How big is the sun's radiation zone?

The radiation zone is the "middle part" of the interior of the Sun. It is adjacent to the core. In this zone, energy travels between the atoms as photons of gamma radiation. Above the radiative zone is the convective zone. Scientists estimate that core energy takes as long as 170,000 years to travel through the dense matter of the radiative zone.

According to NASA, the Sun's radiative zone begins about 108,125 miles from the center of the Sun and ends about 302,750 miles from the center of the sun. So the radiative zone makes up 32 percent of the Sun's volume and 48 percent of its mass.

The exterior of the Sun, where radiation again occurs, is called the photosphere. In some larger stars, the outer layer is radiative and is substantially thicker.