Jeff Wise, age 9, of Houston, Texas, for his question:

Are there more universes besides ours?

When we talk about our Universe, we mean the Milky Way Galaxy. It is, as we know, an enormous cartwheel of stars. Astronomers figure that there are about 100 billion stars in our private Universe. One of them is the sun, with its family of nine planets and their moons. Suppose we set out in a spaceship that could travel at 670 million miles an hour. It would take us about a hundred thousand years to cross our Galaxy from side to side.

Surely this enormous wheel of stars is big enough to fill every corner of outer space. Surely there is no room for any other universes. Or so you might think. But the truth is that Out There, our private Universe is nothing special. Astronomers tell us that their powerful telescopes have photographed hundreds and even thousands of other universes. Nobody can say how many more there are because our telescopes can see only so far. But as far as they can see, there are starry universes scattered through outer space.