You probably think the sky is blue because of the ocean and air and reflections or something like that. But how does it turn red sometimes? Or orange? Or, rather, why does the sky have to be any colour at all? PBS explains it so you can explain it to your future kid.
PBS' It's OK To Be Smart series explains:
In this episode, I'll tell you not only why the sky is blue, but why it's red at sunset. It turns out, those colours are all part of the same sunbeam. And when you're looking at a blue sky, you could be sharing a special moment with someone thousands of miles away. Next time a kid (or the kid inside you) wants to know why the sky is blue, you'll have science to back you up!