What Makes the Colors in a Rainbow?

If you have a prism, you can separate sunlight into its individual colors. A typical prism looks like a triangular column of glass. As light passes through, the glass bends the light. The bending lets you see the visible spectrum: red, orange, yellow, green, blue, indigo, and violet.

WORDS to KNOW

Rayleigh scattering: process by which molecules in the atmosphere split or scatter different colors within white light. [RALL-ee SKAT-er-ing]

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Global Explorer

A globe is a model of Earth. Find a globe and become a global explorer.

  • Find the globe's axis. It runs through the middle of the globe from the North Pole to the South Pole. Earth spins on its axis. The axis is tilted, relative to the sun. It takes 24 hours, or one day, to make one complete rotation.

  • Spin the globe eastward. This is how Earth rotates.

  • Darken the room. Then shine a flashlight at the globe from the side. Let the light hit about half the globe's surface. Now spin the globe eastward again. Parts that are lit would have “day.” The moving edges of light and darkness represent sunrise and sunset.

Rainbows result from nature's prisms. Sometimes after it stops raining overhead, droplets stay in the air ahead of you. If sun shines from behind you through the droplets, the drops act like prisms.

But light's reddish wavelengths are longer than the bluish wavelengths. They arch over the shorter wavelengths. This makes the rainbow curve.

Don't search for a pot of gold at the end of the rainbow! As you move, the projection of the rainbow moves too. When the air dries, the rainbow disappears.

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