Radio Waves

Radio waves are a kind of invisible energy that travels through the air and even through space. We cannot see or hear them, but machines can. They help carry music to your radio and shows to your TV. Phones and Wi-Fi use them too. Radio waves move at the speed of light.

How We Use Them

Radio waves help us share information without wires. A radio station sends waves out from a tall tower. Your radio picks them up and turns them into sound. Cell phones use radio waves to make calls and send texts. Even your Wi-Fi router uses them to connect your computer to the internet.

An animation shows how a radio antenna catches invisible waves.
An animation shows how a radio antenna catches invisible waves. (Chetvorno / Wikimedia Commons)

Radio Waves in Space

Stars and planets in space also give off radio waves. Scientists use giant dishes called radio telescopes to listen for them. These waves can teach us about galaxies far away. NASA uses radio waves to talk to spacecraft. Signals from Mars take minutes to reach Earth.

Fun Facts

  • Radio waves were first discovered by Heinrich Hertz in 1887.
  • Some radio waves can be longer than a football field.
  • Radio signals from Earth have already traveled past many stars.

Did You Know?

The unit we use to measure radio waves, called the hertz, is named after the scientist who first proved they exist.