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General Physics Science Fair Project

Why is the Sky Blue?

Why is the Sky Blue? | Science Fair Projects | STEM Projects
Have you ever wondered why the sky is blue? Let's find out! We can use a flashlight, glue sticks, and polarizing filters to model the scattering of light by the atmosphere, which creates the blue sky and red sunsets.


The hypothesis is that the sky is blue because blue light is most readily scattered from sunlight in the atmosphere.

Method & Materials

You will shine the flashlight into one end of a glue stick and hold the other end of the glue stick approximately one centimeter from the white background. You will then place two glue sticks end to end, and attach them together with the clear tape. You will also place a polarizing filter between the flashlight and the first glue stick.
You will need a Mini-MagLite or penlight, 4 to 6 glue sticks (must be the clear ones used in glue guns), a white background (paper, wall, or cloth), clear packaging tape, and two polarizing filters.


We can conclude that the sky is blue because blue light is most readily scattered from sunlight in the atmosphere, just as blue light was most readily scattered from white light in the glue sticks. At sunset, the sun is low near the horizon, and light travels through a greater thickness of atmosphere before reaching our eyes than it does when the sun is higher in the sky, making the sunset red.

Why do this project?

This science project is interesting and unique because it uses a simple model to demonstrate why the sky is blue and sunsets are red.

Also Consider

Experiment variations to consider include using different colors of light and different lengths of glue sticks.

Full project details

You can find additional information and details for this science fair project here. Have fun exploring!

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