Almost all the light given off by the Sun comes from the photosphere,
or visible surface. Actually, the Sun doesn't have a real "surface"
because it's a ball of very hot gas. The layer of the Sun that emits
visible light is the one we see as the solar surface. Most of this
light is at visible wavelengths, but higher regions of the Sun's
atmosphere give off light ranging from X-rays through to radio wavelengths.