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Can You Reverse a Rainbow? Try for Yourself

Whether a Pink Floyd fan or not, many people are familiar with the image of white light flowing into a prism and dispersing the colors of the rainbow on the other end.

White light contains all the colors of the rainbow. Each color travels at a different wavelength, which is why under the right conditions white light can be split into all the colors of the rainbow.

So if the colors of the rainbow come from white, is there a way we can make white out of the colors of the rainbow? Let’s find out.

Sir Isaac Newton was a famous scientist who asked this very question more than 300 years ago. One of his ideas was to make a disc with wedges of the colors of the rainbow and spin it really fast to see if all the colors combined would return to white.

(Photo by Angela Rafac)

We will make a variation of Newton’s color disc to test out his theory. Newton’s original disc was seven wedges, one for each color of the rainbow. We will include the color white and make eight wedges. Why? Because we can fold our circle in half three times to easily create eight equal-sized wedges.


  • A CD or DVD

  • White paper

  • Scissors

  • A marble

  • A small 1-inch bottle cap (preferably white)

  • White paint and a paint brush to make the bottle cap white (optional)

  • A crayon or colored pencil for each color of the rainbow (ROY G BIV: red, orange, yellow, green, blue, indigo and violet)

  • A pencil

  • A glue stick

  • A hot glue gun and a hot glue stick (Make sure you have a parent or trusted adult’s permission and help.)

  • A ruler


1. Trace a CD on a white sheet of paper and then cut it out.

2. Fold your paper circle in half three times. Unfold it and you will have eight equal-sized wedges. (To make 24 smaller wedges, see the note below.)

3. Color each wedge a color of the rainbow. Leave the eighth wedge white.

4. Use a glue stick to attach your paper to the top side of a CD or DVD.

5. Poke through the paper at the center hole in the disc and gently tear away the extra paper.

6. Use the glue gun to attach the marble in the bottom hole of the disc. (Make sure you have a parent or trusted adult’s permission and help to use a hot glue gun.)

7. Use the glue gun to attach the cap over the marble on top of the disc. (A white top works best, so you can paint the cap white if you like.)

8. Viola! Spin the top and see the magic.

Note: To make 24 wedges, estimate and gently mark two spots making three equal sizes between each wedge. Use a ruler to make an even crease across the circle. When you color, go in order of the colors of the rainbow, using each color and a white space three times.


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