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Originally Posted by Question
I guess I notice that there is more atmosphere that the observer is looking through when it's on the horizon, then when it's strait up. your eye path to the sun encounters less atmosphere, therefore it's a possibility that it has something to do with how much atmosphere is in the way of the sun. Hmm. that's a good point.  |
Excellent logic, and that is the answer. The real color credit belongs to our atmosphere and not the Sun itself. Though I would bet most people do not know this....yet.
Looks like from your last post you have quickly studied this issue. How much aerosols play a role, I can not say, but the N2 and O2 molecules (representing the majority of our atmosphere) are small enough, obviously, to allow what is known as Rayleigh Scattering, or Tyndal-Rayleigh Scattering, or just elastic scattering. It was discovered that when particles are a good bit smaller than the wavelength of light, that light will take off in all different directions (scatter) without loss of energy, so they maintain their "color". Also, the amount of scattering varies as to the 4th power of the wavelength (actually an inverse relation). The wavelength of red light is about 1.5x that of blue (depending on which part of red is compared to which portion of blue). So, (1.5)^4 = 5, roughly, which is the number of times blue light will scatter more than the red light. At the extremeties of their color range, the scattering is closer to 9x, I think.
The result is as you stated, removing more of the blues and greens and leaving more of the yellows, oranges, and reds, will first produce a yellow result followed by an orange result (rarely a red result unless the atmosphere is loaded with smoke particles from fires or volcanoes).
So, we know the Sun is not yellow. Surprisingly, the true color of the Sun is not fully defined.....yet.
[It is mostly white, but there is a chance it is a little blue in the middle portion of the disk. This assumes the observer is in space and is seeing it at a very reduced intensity to allow normal photopic vision.]