The document discusses the structure and composition of the Sun. It has 6 layers: the core, where fusion occurs at 15 million degrees Celsius; the radiative zone, where energy moves by radiation; the convection zone, where hot gas currents transfer energy; the photosphere, the visible surface; the chromosphere, a thin pinkish layer; and the corona, the outermost low density layer. The Sun is mostly made of hydrogen and helium and produces energy through the fusion of hydrogen into helium. It contains over 99% of the mass in the solar system and has prominent features like sunspots and solar winds.