Asteroid Speed

A recent article (“Heat From Asteroids Killed Early Life Forms, Scientists Say,” Science/Medicine, Nov. 13) reports that a team of researchers from Stanford University have determined “that a 260-mile-wide asteroid striking the Earth at a speed of 3,672 m.p.h would create so much heat that the oceans would boil dry.”

Because this is a calculation that students of introductory physics can perform, I have given it to my class as a special assignment. I wonder if they will confirm the results of my own calculations--that the correct figure for the required speed is, in fact, 3,673 m.p.h.

A. JOHN MALLINCKRODT

Assistant Professor of Physics

Claremont Colleges