Becky Bradley, age 9, of Phoenix, Ariz., for her question:

What is a tektite?

Tektites are strange, glassy stones that come in neat shapes such as balls and buttons, disks and dumbbells. Where you find one, there are sure to be many more strewn around on the ground. Scientists tell us that these unusual stones were melted in terrific heat and hurled through the air. Perhaps they were formed when monster meteorites crashed down on the ground. Some scientists suspect that they splashed out into space ages ago when giant meteorites bashed down on the moon. If this is so, then a tektite may be a real moon rock that was thrown onto the earth in the dim distant past. But at present, nobody is sure.