[stouset]

The sky isn’t inherently blue. It’s essentially colorless.

Only due to Rayleigh scattering do we perceive it as blue, but that’s not due to the absorption and reflection of different wavelengths we associate with innate color. Note that the color changes depending on the angle of the sun, even to the point that it’s purple and red at a few times during the day.

[quonn]

Perhaps, only because the sky is blue we perceive blue as blue. If the sky were red we would perhaps perceive all red like we do blue.

Our perception of the important colors (sky blue, ocean blue, vegetation green, …) probably evolved along with our physical needs.