OK, Captain Obvious here, trying to make a point.
Some people who profess an interest in science make claims such as, “The sky isn’t really blue,” and then go on to explain how the sky really isn’t blue. They’ll refer to things such as Rayleigh Scattering, wavelengths of different colors of light, yadda-yadda-yadda. It’s all wonderful, and they’re no doubt right about all their nattering, except… the sky stubbornly remains blue.
I think probably where these “scientists” go wrong is in talking about the sky, since it’s not quite a thing. It’s an effect we see as a result of looking up through a layer of air and moisture. It seems to be a solid thing, maybe not so terribly distant from us – but it’s basically air.
So after all the explanation of scattering light and how the color blue is scattered more than red because of its shorter wavelength, we wind up with the peculiar notion that the sky only appears to be blue; it’s not really blue. Except, as I said, it’s not really a sky, either.
In the meantime we mere mortals continue to believe the ridiculous notion that the sky is blue; and really, it is.