Peggy McHargue, age 11, of Frankfort, Kentucky, for her question:

What is a will o' the wisp?

Will o' the wisp, is a certain something that likes to fool people. As a rule, it is seen at night as an eerie light    perhaps a green or blue patch of ghostly pale haze, perhaps an eerie flame of dancing candlelight. The most likely places are marshes and moist meadows. Lately, a few will o' the wisps have been masquerading as flying saucers    scaring people out of their wits.

You would expect modern science to have a practical explanation for these weird, hazy lights. But nobody can prove what really causes them. Some scientists suspect that they may be gases that escape from decaying vegetation. One may be methane gas that gets warm enough to glow in the dark. Or possibly the decaying marsh plants give off gases that have a built in glow of their own. Nobody so far has solved the secret of will o' the wisp    though most people agree that it has nothing to do with flying saucers.