Kim Mountain, age 12, of Moorsville, Indiana, for his question:

What is the sun's diameter?

The sun's diameter is estimated to be about 864,000 miles, which is more than a hundred times wider than the diameter of the earth. However, their diameters may be misleading when you come to compare their actual volumes. If the sun were hollow, which, of course, it is not, it would have enough space inside to swallow a million earth sized planets and still have room for a sizeable portion of dessert. Their comparative masses also are misleading. The sun is a ball of blazing gases and, for its size, our little earth may be the densest, heaviest planet in the Solar System. Though the sun is over a million times bigger, it is merely a third of a million times more massive than the earth.

Seen from our skies the moon and the sun appear to be the same size. Actually, the sun is 400 times wider than the moon    but it also happens to be 400 times farther away. When you hold a pencil at arm's length and close one eye, it is just wide enough to cover the lunar disk. This width equals about half a degree of sky distance. Naturally it is very unsafe to look directly at the dazzling sun. But seen from the earth the solar disk also occupies about half a degree of sky distance