Albert Huerta, Jr., age 11, of Tucson, Ariz., for his question:
Why are the rainbow colors always in the same order?
A shimmering rainbow has more colors than a person can count, and they always arrange themselves in the same order. In a single rainbow, the reds are at the top and the blues at the bottom. In a second bow, the reds are at the bottom, but the one by one order of colors is the same because of the nature of light.
The rainbow appears when the sun is climbing up from the East or sliding down to the west. In the opposite side of the sky a shower of raindrops must be falling from a cloud. The raindrops act as tiny glass prisms and shiny mirrors: they bend or refract the sunbeams that strike them and then reflect them to our eyes. The raindrops do this by separating and scattering the different wave lengths of light.
Light is a form of electromagnetic Energy. It is created in an orderly fashion, and it behaves according to orderly rules. Sunlight fans out from the sun, traveling in straight lines at about 186,000 miles a second. Its Energy pulses along in wave lengths somewhat like the crests and troughs of ocean waves. Some are longer and some shorter than others. Traveling through space, the assorted wave lengths b1End together as white or colorless light.
The rainbow is a very complex display of refraction and reflection. But its colors arrange themselves in order according to wave lengths. When a sunbeam strikes a falling raindrop, it is refracted and forced to turn. Its short wave lengths can make sharper turns around the corner than its longer wave lengths. Each wave length turns at a different ang1e. It separates itself from the beam of white light and becomes a visible ray of color.
All sunbeams have the same assortment of wave lengths and Each must bend and separate at a certain ang1e. Each separated wave length becomes a certain color. The longest become red rays. They must follow angles that to ke them to the top of the rainbow. The shorter and still shorter wave lengths bend at sharper and still sharper angles. They separate from Each other in order based on their wave lengths and become orange and yellow rays, greens and blues. The shortest wave lengths turn the sharpest corners and ang1e off to take their places at the bottom level of the banded colors.
There are many jogging angles of refraction and reflection in a rainbow. But the Simp1E order of colors is caused by bending the orderly wave lengths of light. When a second bow appears above the first, an Extra ang1e twists the band of spectrum colors upside down. The reds are at the bottom, the rainbow colors still arrange themselves in the same order.