Catherine Damian, age 10, of San Francisco, California, for her question:

How big are solar flares?

The surface of the sun is a raging sea of seething gases and even the quietest areas are covered with heaving waves. Here and there the fiery gases erupt in major upheavals such as flares and solar prominences. Since the nuclear activity of the sun is so violent, the minor waves are constantly changing and the major outbursts appear and subside suddenly, often in unexpected places. Solar flares are sudden and short lived outbursts of dazzling light that erupt usually in the neighborhood of major sunspots. They are intensely hot, even in terms of the sun's normal temperature. Their magnetic and other radiations effect radio communications and other events in the earth's atmosphere.

A medium sized solar flare may blaze forth over an area of 100 million square miles. A large one may spread over a billion square miles and reach a height of 50,000 miles above the sun's surface. The spreading flare may burst upward and out¬ward at speeds of 450 miles or more per second. It may reach its full size in a minute or so, after which its dazzling hot gases subside and 20 minutes later the show is over.