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how thick is the solar surface?

 

Imagine a foggy day. You can hear a car approaching but you can’t see it.
Then the car’s headlights appear for the first time Mouse over. As the car draws closer what do you see? Mouse over

 

Fog and lightsNow 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.

How far is 400km? - 400km is about the distance from London to Middlesborough

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

Cross section diagram of an apple
Apple cut open

The Sun is a hot ball of gas and plasma.
It doesn’t have a hard surface like the Earth. We just use the word ‘surface’ as a convenient way to describe the part of the Sun we can see in visible light!

   

 

   
 
 

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