Main purpose of this lecture is to present on Structure of Sun. The sun has six layers. Three layers, the corona, chromosphere, and photosphere, comprise the sun’s atmosphere or outer layer. The other three layers, convective zone, radiative zone, and core, comprise the inner layers, or the parts of the sun that are not seen. Core: 0-20% of radius; energy produced by nuclear fusion. Radiative Zone: 20-70% of radius; energy travels as thermal radiation. Convective Zone: Outer 30% of Sun; Energy moves by convection.