short explanation: Blue light gets scattered (spread) around much more than all the other colors from the sun, causing the sky to appear blue for a longer one (plus why the sea is blue and clouds are white) have a look here - http://www.why-is-the-sky-blue.org/why-is-the-sky- blue.html
Spellmaster,
Frankly, I don't care. U have made a lot of assumptions in your response however. The Colour of the Sky is a heading, and therefore technically qualifies for capitalisation on the dominant words.
And you have called yourself Spellmaster, whereas the error that you pointed out is, in fact, a grammatical one, and therefore does not fall under the scope of a "Spell"master.