Why is the Sky Blue Science Experiment

Have you ever wondered why the sky looks blue?

In this Why is the Sky Blue science experiment, little learners can see for themselves how the blue wavelength is scattered faster than the red light from the sun. The simple experiment needs only a few things, but it can be a fascinating launch pad for discussions about the sky, the sun, the solar system, and even the weather. In fact, we will be featuring this experiment in our Science Sleuths: Wild Weather class!

Why is the Sky Blue? Science Experiment

Thought Question: Why is the sky blue?


  • Measuring cup filled with 2 cups of water
  • A clear glass
  • Flashlight
  • Tablespoon
  • Milk
  • Safety goggles
  • Paper towels


  1. Put on your safety goggles and place a paper towel down on your work area in case the water spills.
  2. Fill the empty glass halfway with water from the measuring cup.
  3. Add one tablespoon of milk to the water in the glass.
  4. Stir.
  5. Shine the flashlight through the milky water* and watch as the water begins to turn blue.

*You may need to shine the flashlight up from the bottom of the glass to get the best results.

Conclusion: The sky looks blue, because the blue wavelength scatters faster than the other wavelengths in the atmosphere. At sunset, we see the red and orange sky, because the blue has already been scattered out throughout the day.


How’s the Weather? Song for Kids

Happy experimenting!

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