Charles M. Jones, Jr., age 13, of Gastonia, North Carolina, for his question:

How does radio travel through space to the moon?

This miracle is demonstrated every time a lunar mission transmits conversations and TV pictures from the moon. Actually the radio that makes this possible is a natural phenomenon that belongs to the universe. It has been broadcasting through space since time began. The miracle is in how mankind has learned to use it to carry sound and visual signals, for example, between the earth and the moon.

The lunar missions were crowded with drama that none of us will ever forget. No doubt the greatest moment occurred on July 20, 1969, when the astronauts of Apollo 11 landed on the moon. Commander Neil Armstrong set up a capsule TV station and fixed a lens to the camera. Moments later, his spoken message reached the sets in our living rooms. We saw the leg of the LEM, Eagle, and the plaque that reads: "Here men from the planet Earth first set foot on the moon."

That miracle was transmitted by radio    by waves of electromagnetic energy that traverse the vast reaches of space    with no trouble at all. Radio is related to infrared rays and visible light, ultraviolet, X rays and gamma rays. All of these are forms of electromagnetic energy that combine both electric and magnetic fields. All of them fan out from a source, traveling in straight lines at the speed of light. All are powered by their own energies to cross through space.

The phenominal cosmic travelers are grouped together as electromagnetic radiation and neatly charted on the electromagnetic spectrum. The various categories are based on wave lengths, which range from short gamma waves measuring 250 trillions of an inch to radio waves, some of which are measured in miles.

Near the center of the spectrum is the skinny band that belongs to the short waves of visible light    the only form of electromagnetic energy that our senses can perceive without mechanical assistance. Next to this band are the slightly longer wave lengths of infrared, microwaves and radar. Then come the longer waves we use to transmit radio and TV signals around the earth    and way on out into space. equipment is used to harness them to carry and deliver our messages. Radio and TV broadcasting stations generate and transmit powerful carrier radio waves. Coded signals are added to them as extra electrical impulses. These too travel silently and invisibly. They are captured by antennas and relayed to receiving sets which decode the signals back into audible sounds and visible pictures.