Why is the sky blue?

After two months of inactivity here, I figured it's high time to pick up this blog again. I actually started to write several blogs in the past few months but figured that nobody would be interested in what I have to say. Now that I've gotten over that and I realize that no one is interested in these random things, I've decided to write them anyway.

About a month ago I purchased a book from Barnes & Noble called "The Science Answer Book." Now during conversation I can impress my friends with my random knowledge of all things science. For instance, the next total solar eclipse visible in the US will occur in 2017 in a 200 mile line from Oregon to South Carolina. It was meant as a coffee table book. I'm probably one of the few that reads it before I go to bed at night.

Anyway, last night I was reading and refreshed my memory on a question that I'm sure I will get in the next 1 to 3 years. Why is the sky blue?

Interestingly enough, this question also lends itself to the question, why is the sun yellow? Well, here's the basic answer to both questions as well as why the colors change at sunset.

All the colors of the light spectrum have different wavelengths, red has the longest wavelength, blue has the shortest. When all the colors of light combine they produce white light. Since blue has the shortest wavelength it has the most opportunity to collide with the particles in our atmosphere on it's journey from the sun to our eyes. It does collide with the particles of our atmosphere, so the blue light rays from the sun bounce around in the atmosphere and end up coming at us from other areas of the sky, rather than straight from the sun. Since the blue light rays are dispersed, the only light rays left are red and green, which combine to make yellow light (hence the sun looks yellow). As the sun nears the horizon, the light has more atmosphere to travel through to reach us. More atmosphere means more light colliding with particles, both blue and green light are dispersed, leaving the sun looking red and the sky looking pale blue. When the sun reaches the horizon, the atmosphere is so thick that even some of the red light collides with the atmosphere and creates beautiful shades of purple.

Well, that's my random fact of the day. I'll try to keep up on posting here.