Kay $aggett. age 9, of Boise, Idaho, for her question:

Why isn't the skv always blue?

Way out in space, the true color of the sky is velvety black. We cannot see its true color because we see it through a filmy veil. This veil is the airy atmosphere that reaches hundreds of miles above our heads. The sunbeams must pierce through it on their way down to the earth. And on the way down, air plays tricks on them. It steals some of their rays and uses them to color our skies with basic heavenly blue. At dawn and sunset it may steil red and yellow rays and splash them over the sky.

The airy atmosphere is always adding to its basic artwork with blobs of white and ~_ streaks of grey, with pearly hazes and dark glowering curtains. It uses water vapor to paint these cloudy pictures. The sun evaporates the vapor from our watery earth and it mingles with the other gases of the air. Some of it changes back to droplets of liquid water, small enough to float aloft. This forms the clouds that drift overhead and hide for a while the heavenly blue of the sky.