Roxanne Verhines, age 8, of Beech Grove, Ind., for her question:

How does radar figure the distance of a target?     

A radar antenna sends out a pu1se of short wave radio and waits for the beam to Strike an object and return with an Echo. Since radio travels at the speed of light, The distance from the antenna to the target and back to the antenna was covered at 186,000 miles a second.     Suppose the radio pulse returns in one second. WE know it has traveled a total distance of 186,000 miles, and the target must be half this distance away. Radar Beams, however, aim to strike objects just a few miles away, and they go out and return in a few microseconds. If an echo returns in 50 microseconds, the beam has traveled about three miles, so the target is roughly a mile and a half away.