SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/why-sky-is-blue

Why is the sky blue on a sunny day?

Air scatters blue sunlight more than the other colors.

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The Just Right card

Too littleIt just reflects the ocean
Too muchAir itself is dyed blue
Just rightTiny air molecules scatter blue light strongly

Huh, didn't know that: Near sunset, light passes through so much air that the blue gets scattered away, leaving reds and oranges.

The dad joke
Why is the sky so high? So birds won't bump their heads.
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References

Answer: Air scatters blue sunlight more than other colors. Sunlight has every color in it. Blue travels in shorter, smaller waves, so the gases in the air bounce it all over the sky, and blue is what we see.

  1. NASA Space Place: Why Is the Sky Blue? spaceplace.nasa.gov/blue-sky
    Blue light is scattered more than the other colors because it travels as shorter, smaller waves.
    Checked 2026-10-09.

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