Why does the sky appear to be blue?

The sky's zenith appears centered in this dayt...
The sky’s zenith appears centered in this daytime photograph taken looking up through trees (Photo credit: Wikipedia)

Several months ago I must admit I met possibly one of the greatest people of my acquaintance. A couple of days ago we struck up a conversation about the celestial sphere better known as the sky. His question was simple, “what exactly is the color of the sky?” Perhaps for you this is common sense or something you have been familiar with for one reason or the other. For me however, this was actually news. I had never given it much thought, the sky has always been blue except at sunset and sunrise and that was that! So I went online and did a little research.
Here is what we know for sure:

  • The sky is blue at daytime
  • The sky is mostly dark in the night
  • The color of the sky changes at different times such as the ever-so-romatic reds, oranges, yellows and purples at dawn and sunset.

What I did not know however is this:
According to Wikipedia the sky seems to be blue in the day time since the air distributes blue light more than it does red. This is referred to as scattering in scientific terms. The source of light off course is the sun. As we all should be aware, the light from the sun is white, which we were often told in school, is the presence of all colors. The human eye can only see certain wavelengths from the spectrum- the shorter end of the spectrum to be specific- which causes the sky to seem bluer than the original light from the sun. NASA explains that blue light rays travel as shorter, smaller waves hence we mostly see a blue sky. At sunset the shades of orange and red in the sky are more visible because the molecules in the air scatter the blue light away from the line of sight.
Have you always known this, or is it a revelation to you as it was to me? What more can you tell us about the sky?
© Valerie Chela N, all writers herein and Memoirs of a Kenyan, 2013. Unauthorized use and/or duplication of this material without express and written permission from this blog’s authors and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to appropriate author of content and Memoirs of a Kenyan with appropriate and specific direction to the original content.

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