What is a rainbow?


Where do rainbows come from? Is there a special fairy up in the sky who paints the rainbow onto the sky using her magic paintbrush? Or do the colors fall out a big bag of candy that somebody spills out of a plane??

To understand where rainbows come from, first you have to understand where color comes from; color is the way our eyes interpret the energies contained within a beam of light. White (uncolored) light contains a large spectrum of colors. When light touches an object, some of these energies are absorbed (taken in) by it, and others are reflected (cast back). It's the energies that are reflected which your eyes collect and then interpret as a specific color!

But the situation with reflected and absorbed colors is a little different when the object being hit by light is a droplet of water: When light hits something like a droplet of water from the right angle, it bends and splits the energies so that when they're reflected back at you, they're fanned out into the colorful display of a rainbow! That's why rainbows mostly come out after it rains and there are more water droplets for light to hit! Neat!!

by Mya Kagan (Whyzz writer)

Further Information

Lots of people will describe rainbows as having seven specific colors: Red, orange, yellow, green, blue, indigo, and violet. When you look at a rainbow, you might even be able to see each of these individual colors. However, these are actually just some of the many, many colors contained within the beam of light creating the rainbow! Have you ever seen a color wheel? If so, then you already know that there are an endless number of shades any one color can be! We often name the "seven colors of the rainbow" or the "seven colors of light" because it can be a helpful way of dividing up the endless colors that are really there!


Nebel, Bernard J. Ph.D. Chapter 16 Light, Rainbows, and Waves. Nebels Elementary Education. Maryland: Nebels Press for LearningHow are rainbows formed? Science Kids. Dartmouth College Computer Science Department.