Radio waves have the longest wavelengths in the electromagnetic spectrum. They are used to transport information through the atmosphere without wires. They carry signals to your radio, television and mobile phone.
Astronomers like Melanie Johnston-Hollitt use radio telescopes that receive radio waves emitted by planets, stars, galaxies, and nebulas to study the far reaches of the universe.
Image acknowledgement: Galaxies show as small radio emissions in this telescopic image by Melanie Johnston-Hollitt