The hot compact core of the Sun – where the energy is created – has a radius of about 175,000 km. Outside the core is a layer where the energy is transported by electromagnetic radiation or photons. This layer is called the radiation zone. Further out we find the convection zone where the energy is transported as a turbulent churning motion similar to a pot of boiling soup. The visible surface, the photosphere, is only about 400 km thick. Above the photosphere we findthe chromosphere, a layer of thin hot gas extending to a few thousand kilometres. Above the chromosphere is the corona, the Sun´s outermost part of the solar atmosphere.