Why does the sun have to be yellow?

at midday the wavelength of light reaching your eyes is 'yellow' (different wavelengths of light appear different colors, hence the prism effect and rainbows), in late afternoon the light must p thru more air because the angle is lower, and red s better, so as the sun gets lower it goes from yellow to orange to red. therefore anything in the air that blocks light (water vapor, dust, etc.) changes the color you see because certain wavelengths are blocked better than others, ocean water is clear but absorbs all colors except blue, so the blue wavelength is bounced back to your eyes. sunsets are prettier in places with low pollution because not as much light is blocked. it never appears green or blue because they are short wavelengths that air blocks easily, but also the reason the sky is blue. if you went into space with a filter that blocked all wavelengths except blue then it would look blue, unless the star itself put out mostly red wavelengths (red giants)