Why do you post your wisdom only once a week?
Well, when you get as old as me it takes time to get up, get started and then do the work. Also it takes time for me to think of something worthwhile to post.
Why is the sky blue?
Well I take a Iook at it last night and it was not blue, it was black. But you probably meant during the day. That is a tougher question relating to refraction and white light being made of colored light. You better Google it.
Lessons on driving
Never go faster than the car ahead of you.