Ask A Scientist© Astronomy Archive

Author:      doug a foster
Why does the temperature of the Sun cool off from the core to the surface
and then get so hot again in the atmosphere?

Response #:  1 of 1
Author:      jlu
The first part is pretty simple.  The sun's furnace is near the center. 
That is because the gravitational pressure there is so high that thermonu-
clear burning takes place.  The further one gets from the center then the
cooler the solar material.
The second part is more complicated.  There is a lot of funny stuff that
occurs on the surface that involves very strong magnetic fields and a lot of
stirring.  The result is that occasional hot spots flare up and shoot "hot"
material outward from the Sun.