Charles Hertz, Jr., age 13, of Allentown, Penn:

How large are comets?

Comets are like fireworks, They have very little solid matter to show for all their display. They come in a variety of sizes. But the solid old world weighs more than 100,000 times more than the biggest comet known. Light as they are they take up a lot of space.

The huge head of a comet may be 10,000 miles across or even 100,000 miles or more. But stars can be seen right through it. Most likely it is a loose bundle of meteors separated by rare gases. Comets have been known to break up when near the earth. Showers of meteorites, even small stones  have come plummeting to earth.

The tail of a comet may be 500 million miles long. It is made of particles too small to imagine. There is an old saying about the comet's tail, If it were all packed solidly together, it would fit in your hat, This is very close to the truth. Comets are huge bulky members of the Solar family. But they are light‑weights, they have been referred to as a giant snowball.