David Goldreich, age 11, of Toronto, Ont., Canada, for his question:

WHAT HAPPENS WHEN A METEOR HITS THE GROUND?

The wide spaces between the planets are populated with specks of dust, with stones and flying boulders. Our big earth moves around and around in its orbit. Day and night it crashes into thousands of these space traveling meteors. As they come rushing toward the earth, the meteors heat up and glow in the air miles above our heads.

Most of them are small specks that burn up before they reach the ground, but their ashes come drifting down. Stone size meteors are not all burned to ashes. They hit the ground with a thud or fall into the sea with a splash. A boulder size meteor hits with a loud crash and may shake the ground for miles around. Every meteor that strikes the earth changes its name and becomes a grounded meteorite.