How can scientists measure the temperature of the sun ?
If the Sun were not burning, gravity would compress all the gas down into a much smaller space. Since the Sun is bigger than just a ball of gas held down by gravity, we know (along with other things, like the fact that it is glowing VERY brightly) that there must be some source of energy in there. (In the Sun’s case the only thing that can produce enough energy over such a long period of time is nuclear fusion.) If we can measure the size (radius) of the Sun, and have a good estimate of its mass, using some physics we can calculate the temperature in the center needed to hold the rest of the Sun up. The reason that we can’t just look at the radiation (light) that comes from the center of the Sun to measure its temperature is that the Sun is so dense that even the most energetic gamma-rays can only travel a few centimeters in the center before being absorbed by another atom, and then re-emitted a little while later. (This is called Compton scattering). If you light a fire, the farther a
