Beverly Lassiter, age 8, of Newport News, Virginia, for her question:

Why do rainbows disappear?

Rainbows are rather rare and when we see one, it soon disappears. What's more, most rainbows tend to appear during the showery seasons when there's a frequent mixture of sun and rain. As a rule, there are fewer during the gray winter    and we may suspect that rainbows are going out of style. Not at all. We can expect them to appear again with the showers of spring. Sometimes we get a glimpse of several during a week    but this is unusual.

A rainbow is rare because things in the sky have to be just right for it to appear. The sun must be shining in a clear patch of sky and there must be a weeping rain cloud. The glimmering rainbow is a magic trick done with lights and mirrors. The lights are sunbeams, dashing across the sky. The mirrors are millions of glassy raindrops. The sunbeams and raindrops together create the colored ribbons of the rainbow. But the magic is soon over    and it may be a long time before things are just right for it to happen rain.