T. C. Wheeler, age 13, of Rochester, New York, for his question:

Can a pilot hear his sonic boom?

The speed of sound through the air is limited to about one mile in five seconds. The speed of a plane is not. When a pilot bashes through the sound barrier, he surpasses the speed of sound. The sound of the sonic boom spreads out in all directions poking along at its speed limit of about one mile in five seconds. In a few seconds, it reaches the ears of people on the ground. But, it cannot catch up with the pilot after he surpasses the speed of sound.

We refer to the noise as a sonic boom because it occurs when a plane reaches the speed of sound. When it reaches this speed, the surrounding air molecules cannot move fast enough to get out of its way. Air piles up in dense masses. The speeding plane creates shock waves when it bashes through the barrier. Meantime, the pilot is too fast and too far ahead to hear his own sonic boom.