Return of the Space Snowballs; August 1997; Scientific American Magazine; by Powell; 2 Page(s)

It was the kind of news Chicken Little would surely understand: on May 28 Louis A. Frank of the University of Iowa announced that miniature comets (each about the size of a house) are slamming into the earth¿s atmosphere at a staggering rate of some 40,000 a day. This pummeling is far beyond anything astronomers had envisioned based on the known components of the solar system. "If it is true, this is a very important result," comments Heinrich Holland of Harvard University.

But is it true? Frank made a similar announcement 11 years ago, drawing on views of the earth¿s atmosphere made with the Dynamics Explorer 1 satellite. Those pictures contained strange dark spots that Frank interpreted as "holes" in the glow of the upper atmosphere caused by the arrival of low-density iceballs-- tiny cousins of ordinary comets. A number of researchers promptly raised stinging scientific objections to his small-comet hypothesis, however, and suggested that the holes were nothing more exotic than instrumental artifacts. Under a barrage of criticism, Frank¿s ideas faded from view.