Steven Kirkby, age 13, of Somerset, Ky., for his question:

HOW MANY CONSTELLATIONS ARE THERE?

Trillions of miles separate a star from its nearest neighbor, yet when viewed from earth they appear to be in groups. We call these patterns constellations, a name that comes from a Latin word meaning "group of stars." Every star that can be seen with the unaided eye belongs to one of these constellations. There are a total of  88, with 48 in the Northern Hemisphere and the other 40 in the Southern Hemisphere. The most famous, perhaps, is called the Big Dipper  or Ursa Major.