The sun's photosphere is composed of granular cells responsible for heat transfer. These cells cycle heat back to the center of the sun to be reheated.
The sun is composed of three basic layers. Besides the photosphere, the other two layers are the chromosphere and the corona.
The chromosphere is the second layer from the center of the sun. It allows heat and light to pass through to outer space. Extremely hot patches called plages and solar flares originate in the chromosphere.
The corona is the outermost part of the sun's atmosphere. It contains low-density gases and has a light usually overpowered by light from the photosphere. Usually this light is only visible during a solar eclipse.