Thomas Watkins Jr., age 12, of Hughesville, Pa., for his question:

WHAT CAUSES SUNSPOTS?

From time to time, dark patches called sunspots are seen on the face of the sun. Sometimes a strong loop of magnetic lines of force extends through the sun's surface. Where the lines cross through the surface, they lower the temperature of the gas. This gas does not shine as brightly as the surrounding gas, and it appears as a dark patch on the sun.

After a few days, the magnetic loop may break into a number of thinner loops. Each of these loops crosses the surface at a different place. The original sunspot breaks up into several sunspots that form a sunspot group.

The average sunspot has a diameter of about 20,000 miles. Most have an inner part called the umbra and a lighter colored outer part called the penumbra.