"Why are there so many songs about rainbows?" sings Kermit the Frog in a song (about rainbows) called "Rainbow Connection" from 1979's "The Muppet Movie." And it's not just songs that feature rainbows ...

This is what gives us the huge richness of colour in our world when there’s only the simple spectrum of the rainbow ... black, and even blue. When these are all mixed together, you just see ...

It might seem like a simple question. But the science behind a blue sky isn't that easy. For starters, it involves something ...