While the surface of the earth's sun is said to be 5500
°C , (9,932
°F), its corona (atmosphere) is said to range from 0.5M
°C to 2.5M
°C (0.9M
°F to 4.5M
°F.) It is generally averaged at 1M
°C (1.8M
°F). Now THAT's quite a temperature.
What causes this massive difference in temperature remains a bit of a
mystery to Science, though they believe they're closing in on one potential explanation - the answer lying in 'solaf flares', and particularly many small 'solar flares' occurring much more frequently than they had known, prior to 2020 and some observations of about 95
events they'd been able to capture.
In addition, the sun is said to have grown in mass by 20% over the last 4.5 billion years. However, it is said a significant change will be seen by about 5-6 billion more years from now, the mass decreasing and the earth's orbit slipping farther away. (I've been unable to isolate the reason for this suspected change as of yet.)
Naturally, though the Sun requires Co2 to 'burn', it does not 'burn' in the same way our brains think of 'burning'. Rather, it 'generates heat' due to fusion reaction due to the extreme pressure of its mass. (Obviously, if its mass has grown by 20% over the last 4.5 billion years, then the earth's rotation distance from it would also be expected to have decreased over the same period of time, thus the earth's general temperature being somewhat higher today than it was 'yesterday.' This also, I have not yet found discussion of.)
A fascinating subject altogether. Given the requirement for Co2 for its 'burn', I can't help but still wonder why all the available Co2 isn't consumed instantly, at a constant average 1.8 million
°F. I'll keep researching.