And then there are these ones:
Notice anything odd? Yup, that's right...
In the 60s, the sky was Yellow and Pink.
Now, why on earth was the sky such an odd hue? How did this happen?
Personally, I blame the impending nuclear war at the time. Comic book writers knew that, with nuclear radiation damaging our atmosphere and our corneas, we'd all be facing a sky that was no longer blue, or at least didn't look that way to most of us. So they decided to help us, prepare us for the impending apocalypse.
This, my good friends, is the value of comics. Preparing you and I for impending doom since 1961.
(NOTE: All images courtesy of www.mycomicshop.com.)
(NOTE 2: There's also the chance that yellow and pink are more eye-catching than blue. But I doubt it.)