 Now of course the car’s headlights have been on all the time, but until the car was close enough, you couldn’t see them.
A similar situation occurs inside the Sun. An enormous amount of heat and light is produced inside the Sun, but because of all that gas and plasma between you and the source of the light, only the light produced in the outer layers of the Sun (those closest to us) reaches us.
The deepest part of the Sun from which light can just begin to escape is defined as the inner edge of the surface of the Sun. The outer edge of the surface is the point at which almost all the visible light produced is able to escape.
 |
This surface layer is about 400 km thick - which may sound a lot, but remember that the Sun’s diameter is about 1.3 million kilometres, so 400 km is no more that the skin of an apple as far as the Sun is concerned |
 |
|
