Steven Peters, age 12, of Houston, Texas, for his question:

What is the DEW line?

The DEW line has nothing whatever to do with the dew which drenches the ground in the early morning. The capital letters in DEW are initials standing for Distant Early Warning. The DEW line is a fence of elaborate electronic equipment to warn of enemy bombers which might attack from over the North Pole.

It is a series of radar stations, just north of the Arctic Circle, stretching across the roof of the continent from Point Barrow, the northwestern tip of North America, to Baffin Island ‑ almost all the way to Greenland. The targets of enemy attack would be dense industrial centers far to the south. Even if the attacking planes flew faster than sounds the DEW line could give these areas an hour's warming,

There are six major DEW line stations, each covering 500 miles. Smaller stations are spaced at 100 mile intervals, and still smaller stations fill in the gaps. Together they form a radar net, scanning the skies day and night.