Kathy Harbin, Age 71, Of Asheviile, N.C., for her question:     

What gives color to objects?   

 A bluebird is blue in the noonday sun. In the dim light of dusk, he loses some of his brillianee. On a moonless midnight, he becomes grey enough to hide himself in the leafy shadows. Bright light enhances color, but they become drab when the light fades. Objects need light to reveal their colors.     Most objects get their special colors from chemicals called pigments. The pigment in a pink rose is different from the pigment in a marigold. Texture and surfaee may modify colors. Rough granite becomes more colorful when given a shiny surface. But without the help of light, our eyes would be unable to see arty colors at all.     Streams of sunlight fall on the objects around us, and some of this light bounces back so that our eyes can see 1.t. Sunbeams of ordinary white light are Invisible while they travel to the earth. But white light is a b1end of all the Colors of the rainbow. When sunbeams strike the various objects that bedeck our world, they split apart. Our eyes see the separate strands of light as the assorted colors of the rainbow.     When white light strikes a marigold, all but the orange rays of light are Absorbed by the pigments in the petals. The orange is reflected back, and our eyes see this ref1ected ray of light as the color. The pigments in a pink rose reflect a ray of light which our eyes see as a rosy color. All the other rainbow colors are absorbed by the petals.     A lily absorbs none of the spectrum colors of the rainbow. We see its wax petals as white, which is the colorless blend of white light. A lump of coal absorbs all the colors of the spectrum. It looks black, because no colored rays are reflected back for our eyes to see.     Pigments, dyes and other chemicals play tricks on white light and make it show its colors. This happens because light is radiant energy pulsing along on different wave lengths. Each pulse of energy is a hill and valley, and the measure of a wave length is from one hilly crest to the next. Our eyes see the longest wave lengths as red. The shortest waye lengths are the blue rays at the opposite side of the spectrum.
As a rule, the wave lengths of light are measut'ed by the angstrom unit, which can be written as a. or as a.u. There are 100 million a.u.s in a centimeter, and there are 2.54 centimeters in an inch. The wave lengths of white light range between 3500 and 7800 a.u.s. The thickness of a page is equal to about 130 wave lengths of the red rays or about 260 wave lengths of the blue rays.