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Why is the Sky Blue?
What is it about the SKY that makes it look BLUE ?
The celestial canopy and the reasons for its azure colour by day.
The classic blue colour of the sky is no longer a mystery, and it can be explained in an easy-to-understand way. The thing is, light as it comes in, is white. White light is made up of all of the colours of the rainbow added together. Some things, such as rain, or a prism, split light into its different colours. What the sky does, as it's made of plenty of air with various small particles of stuff included, is it tends to scatter more blue light than other colours.
Blue is towards the high end of the frequency spectrum, and all the air and dust scatter it more than the lower frequency stuff such as red. So, with blue light being scattered off it, the sky therefore looks blue.
Of course as the sky is scattering various high frequency light, it's scattering indigo and violet as well as blue. However, what you see is a combination of blue, indigo, and violet, and because of the way the eye perceives things, the result is a sum of colours approximating to... sky blue.
Sunsets are red because that's what's left over from someone else's blue sky.
Here are a few more links to "Why is the Sky Blue?"...
Meanwhile, at Zyra's website (Zyra.org.uk), there's a wealth of interesting stuff to explore. As well as Cheer Me Up, there's a variety of truths and misconceptions explored in detail. Makes many a good tea break!