One radio beam can cover a lot of sky. What's more, visible light waves are only a small fraction of the entire spectrum of electromagnetic radiation. Our eyes can only see this narrow band of light. Using the proper instruments, however, we can detect signals in other parts of the spectrum, including radio waves, x-rays, gamma rays, ultraviolet and infrared light. Astronomers use radio telescopes to observe radio waves coming from stars, nebulae, and other galactic phenomenon.
Radio telescopes can see farther than optical telescopes.
They can see through clouds of interstellar dust, like the Horsehead nebula. They can also see things hidden from telescopes that look only at visible light. For example, by observing radio waves, astronomers can learn about aspects of galaxies that visible light does not reveal. Galaxy NGC 253 Visual image Radio image Radio waves are also good ways for civilizations like ours to communicate. We use radio waves for television and radio broadcasts, among other uses.