From Inside Out:
1. Core: This is the innermost layer, where nuclear fusion occurs, converting hydrogen into helium and releasing massive amounts of energy. The core accounts for about 2% of the Sun's volume but contains 50% of its mass.
2. Radiative Zone: This layer surrounds the core and extends outward to about 70% of the Sun's radius. Energy from the core is transported outward primarily by radiation, with photons bouncing around randomly until they reach the outer layer.
3. Convective Zone: This layer extends from about 70% to 99% of the Sun's radius. The energy transport in this zone is dominated by convection, where hot gas rises and cooler gas sinks, creating a churning motion.
4. Photosphere: This is the visible surface of the Sun. It is about 400 km thick and emits most of the light we see. Sunspots, which are cooler regions, are located here.
5. Chromosphere: This is a thin layer above the photosphere, extending about 2,000 km. It is characterized by bright, reddish emissions and is responsible for the Sun's spectrum.
6. Transition Region: This is a thin, rapidly changing layer between the chromosphere and the corona.
7. Corona: This is the outermost layer of the Sun's atmosphere, extending far beyond the visible surface. It is very hot, reaching millions of degrees Celsius, and is responsible for the solar wind.
Note: There are other smaller features within these layers, like the tachocline, which is a boundary between the radiative and convective zones. However, the seven layers listed above are the primary layers that make up the Sun's structure.
