Carolyn Ratcliff, age 10, of Asheville, N.C., for her question:

How did the craters of the moon get their names?

Way back in the year 1651, an Italian astronomer named Giovanni Battista Riccioli made a map of the moon. A few of the outstanding landmarks had been given names before this. But Riccioli used a system of his own to rename them and to give names to many other noticeable plains and craters. He called the flat plains maria, from the Latin word for seas. He named the craters for famous astronomers and philosophers.

Riccioli invented poetic names for the flat plains that he mistook for seas and for the craters he used two groups of famous men. The craters of the northern hemisphere of the moon were named for famous astronomers of the ancient world. Those of the southern hemisphere were named for famous men still living at the time of Riccioli. Later, astronomers used Riccioli's system as a basis for naming the lunar landscape and added names for features he had not labeled.