Carl Burt, age 12, of Newport News, Va., for his question:

What are the globular clusters?

No one could have found a more down to earth name for these heavenly wonders. A globular cluster is a globe shaped cluster of crowded stars. Tens of thousands of bright stars may swarm together in the razzle dazzle group, and a globular cluster might rate as a miniature galaxy. About 100 of them have been spotted in the Milky Way and others have been found in other galaxies. A few are faintly visible. What seems to be a dim star in the summer constellation of Hercules is actually a globular cluster, a remote ball of crowded stars.

All the clusters are remote from us. They seem to be placed in a spherical halo around the hub of the galaxy. There they form a vast halo more than 120,000 light years wide that extends far above and below the flat, wheeling disc of the Milky Way.