Cindy Ferrie, age 12, of Vancouver, British Columbia, Canada, for her question:

Is it true that light makes colors?

In the world of nature, very few things happen all by themselves. Almost always, several different things work together as a team to 'make things happen. This is the story behind the colors we see in the world around us. Part of the project is performed by special chemicals called pigments. But they need the help of light rays to show us their colors. Red roses and bright blue ribbons lose their colors in the dark. But switch on a light or wait for the sunrise and there they are, bedecked in their colors.

The colors of roses and ribbons are caused by very complicated collisions on a very small scale. In any collision, at least one of the parties must be moving. In this case, it is light, traveling at the breakneck speed of 186,000 miles per second. Color appears when rays of light strike certain objects and bounce back for our eyes to see. The things we see are really pictures or images. Straight rays of light fall upon the scenery, turn around and zoom toward us in straight lines    all at the fantastic speed of 669,600,000 miles per hour.

This fantastically fast event is complicated because light is a complicated form of energy. Daylight is radiant energy that the sun sheds in all directions. It travels in straight lines, but in different wavelengths of pulsing energy. The wavelengths have crests and troughs, somewhat like the waves of the ocean. Every sunbeam is a package of countless different wavelengths, all blended together to make white, or colorless light.

However, a sunbeam of white light is colorless only when traveling. This changes, for example, when it strikes a red rose or a blue ribbon. The collision separates some of its different wavelengths. The rose petals happen to contain a pigment chemical that absorbs all the medium and short waves. The longer waves bounce off and our eyes see them as red color.

The different wave lengths of light have their own colors. But they cannot show them unless they are separated from all the other wavelengths. The pigment in a bow of blue ribbon absorbs all the longer rays of light. This time the short waves bounce back and we see them as blue color.

The colors of light are revealed in the rainbow, when slanting sunbeams strike falling drops of rain. There we see them arranged in orderly bands of red, orange and yellow, green, blue and violets. This is called the color spectrum of light. The shortest waves show the blue rays. The wavelengths of each color band grow longer toward the red end of the spectrum. All the colors we see come from these wavelengths of light.

Roses, ribbons and other colorful objects contain chemical pigments. Green leaves absorb all the wavelengths except green and bounce off the greens for us to see. A snowy lily takes no wave lengths from light. All of them bounce off and we see the original blend of white light. A black button absorbs all the light waves and we see no colors at all.