Diane Flanagan, age 10, of Pittsburgh, Pa., for her question:

What sort of star is a nova?

The word nova means a new star. It appears very suddenly as a very, very bright star where no star appeared before. In olden times, people naturally thought that a new superduper star had been created. We now know that this is not so. A so called nova appears when a very dim faraway star suddenly explodes into a huge dazzling ball of spreading fiery gases.

Nobody is certain why it happens  and it does not happen very often. When it does, a dim little star swells up and explodes like a razzle dazzle bubble. Suddenly the nova becomes brighter by far than arty other star in the sky. Actually, an outer shell of its blazing gases is swelling at speeds of 2 million miles per hour. Usually, the show is over in a few weeks. The star shrinks back to normal, though it may become a nova again at some future time.