Elaine Hutton, age 9, of Peterborough, Ontario, Canada, for her question:

Is there really a planet called Vulcan?

We know for sure that the earth and eight other planets orbit around the sun. It would be nice to think that the sun has still more planet children. Several times the experts have suspected that the Solar System did have more planets, if only we could find them. Some still suspect that there may be, just maybe, a tenth planet way out there at the edge of the solar System beyond little Pluto.

And once upon a time, the experts suspected that there was another planet closer to the sun than little Mercury. They searched and searched and even had a name ready to give it. It was to be called Vulcan after the Roman god who was supposed to forge metal. This is a very warm job because the forging of metal calls for a seething furnace. For this reason it seemed sensible to name the unfound planet Vulcan. After all, it would be closer to the seething furnace of the sun than Mercury. And Mercury is only 36 million miles from the sun. We are three times farther from the furnace. But hot little Vulcan was never found and modern experts say that it never existed at all.