Jon Beasley, age 10, of Chattanooga, Tenn., for his question:

HOW MANY STARS ARE THERE?

There is an almost unbelievable number of stars in the sky. Write down the number two and then put 20 zeros behind it. This figure is 200 billion billion. And there are more than that number of stars in the sky.

The largest star in the sky would more than fill the space between our Earth and the sun. Such a star would have a diameter about 1,000 times as large as the sun's.

The smallest star in the sky is smaller than the Earth.

It is almost impossible to imagine the great distances that separate the stars. The star nearest the sun is more than 25 million million miles away from the sun.

Stars seem to twinkle because starlight comes to us through moving layers of air that surround the Earth. The stars shine day and night by reflecting light, but we can see them only when the sky is dark and clear. During the day, sunlight brightens the sky and keeps us from seeing the stars.