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  • The sky is not blueit’s mostly transparent air which is, at best, the color of whatever

  • light it scatters. Sure, it does scatter blue light more than red light; in fact, the higher

  • the frequency of light, the more it gets scattered by the atmosphere, so ultraviolet scatters

  • more than blue, which scatters more than green, more than yellow, more than red, more than

  • infraredbut still, only a tiny bit of light scatters while most of it goes straight

  • through, which is, you know, how the sun can light up the ground, why we can see the moon

  • and stars, etc.

  • The sun itself actually emits a wide range of frequencies of light, and our human eyes

  • perceive this particular combination as "whiteor neutral in color. The vast majority of

  • the sky appears blueish because sunlight that was trying to go somewhere else got scattered

  • by the air and instead ended up in your eye. Bummer. It still has a wide range of frequencies

  • in it, but with slightly more blue than in white light, roughly the same amount of green,

  • and less red.

  • You can see a simple demonstration of this on a computer if I take a white background,

  • add a bit of deep blue and subtract a tiny bit of pure red: I get a nice sky color!

  • And the reverse effect happens when you look near the sunlight that was trying to

  • get to your eyes gets scattered away, and so the remaining light has a lot less blue

  • and slightly more red compared with white light, which is why the sun and the sky directly

  • around it appear yellowish during the day! At sunset, there’s even more air for the

  • light to scatter off of before it reaches you, hence the even richer oranges and reds.

  • And of course you can do the computer demo again, this time subtracting pure blue and

  • adding a little red: voila! Noontime sun. Subtract more blue and add even more red?

  • Sunset orange.

  • So, the sky is not blue; it’s a stage upon which all colors dance. Red colors tend to

  • dance in straighter lines, green colors more randomly, and deep blue colors dance the most

  • frenetically of all. Yet at some point, they ultimately dance their way into your eyes,

  • and my eyes, and to the earth and into space, so that everyone everywhere can appreciate

  • the grand ballet

  • of light.

The sky is not blueit’s mostly transparent air which is, at best, the color of whatever

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