Anne Frances Applegate, age 9, of Huntsville, Ala., for her question:

WHY IS THE SKY BLUE?

Sunlight is made of all colors of the spectrum, Just as you see them in a rainbow. The sky looks blue because sunlight is broken and scattered by tiny particles of air, dust and water vapor in the atmosphere.

When light passes through the atmosphere and hits the tiny particles in the air, the blue part of the light is just the right wavelength to be scattered, and the scattering makes the sky look blue. Mornings and evenings the light passes through a thicker layer of atmosphere causing orange and red waves of light to break up.