Science with Shields: Episode #78 – Why the sky is blue


ALTOONA, Pa. (WTAJ) — In this episode of Science with Shields, Christy Shields shows you why the sky is blue.

What you need: 

  1. Flashlight
  2. Soap/Milk
  3. A clear glass
  4. Water


It is best to do this experiment in a dark room. First, fill your glass up with water. Add soap to get a milky color. You can also use milk to achieve this. Point the flashlight at the cloudy solution and notice how the mixture gets a light hint of blue!


The sky is blue because of the scattering of light. Like sunlight, the white light from the flashlight is made up of a rainbow of colors. We don’t see all of these colors individually, but just as a white light . Once the light is scattered through an object, we can see individual colors. Blue light has a shorter wavelength than the other colors scattered. This is why we see blue tint to the solution in the glass.

The sky is blue from the refraction of light. Light bends when passing through the air to another medium, for example, like water. When it’s a clear day, the sunlight goes through then atmosphere and the light is scattered through the air molecules giving the sky its blue color. Again remember, its because blue has a shorter wavelength then the other colors. Also, blue is a color that is easier to see with the human eye compared to some other colors.  

Check out more Science with Shields episodes on WTAJ Plus.

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