6
votes
3answers
202 views

Can visible light be emitted from a non-thermal source?

I was reading about thermal and non-thermal radiation and I was wondering if visible light can be emitted from a non-thermal source?
2
votes
1answer
150 views

What is the diameter of the sun as a function of wavelength/frequency (around 10GHz)?

I have this vague recollection of being told that the diameter of the apparent surface of the sun is a function of what band you observe it in. I'm looking for a model of this that works for bands in ...