Scientists Say: Radio Waves

Radio waves carry signals not only between our electronic devices, but also across the cosmos

a white radio dish points toward the pink sky in the desert, with other white radio dishes in the background

Radio telescopes like this one tune into radio waves from outer space to learn about stars and black holes and other objects.

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Radio waves (noun, “RAY-dee-oh WAYVS”)

Radio waves are one type of electromagnetic radiation.

Electromagnetic radiation includes visible light, infrared light, X-rays and other types of energy. All of these travel through space as waves. But they have different frequencies. A wave’s frequency is how many times it wiggles back and forth per second. Radio waves have the lowest frequencies of any electromagnetic waves. They wiggle a few thousand to a few trillion times per second.

Many technologies use radio waves to send and receive signals. Take the radio in your car or home. To broadcast music or news, a radio station’s tower sends radio waves out into the air. Those waves travel to radios, which translate the incoming waves into vibrations. Vibrating speakers inside a radio create the sound waves heard as radio programs. TV broadcasts work in a similar way. Towers send out radio waves that carry data for both sounds and images. TVs then pick up those radio waves and decode them to display movies and shows.

Cell phones and wireless computer networks also send and receive signals as radio waves. So do radar systems and GPS devices. In all of these cases, the device that generates radio waves is called the transmitter. The device that picks radio waves up is called the receiver.

But technology is not the only thing that can create radio waves. Lightning gives off radio waves. So do lots of objects throughout the universe. Examples include pulsars and quasars.

Radio telescopes on Earth can tune into the radio waves shed by those distant objects. Observing the waves can then provide insight into those distant sources are made of, how they’re moving and more.

In a sentence

Astronomers collect radio waves to take pictures of black holes

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Maria Temming is the Assistant Managing Editor at Science News Explores. She has bachelor's degrees in physics and English, and a master's in science writing.

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