Home > Encyclopedia of Science > Radio Astronomy

• Words to Know
• Origins of radio astronomy
• What radio astronomy has revealed

Matter in the universe emits radiation (energy) from all parts of the electromagnetic spectrum, the range of wavelengths produced by the interaction of electricity and magnetism. The electromagnetic spectrum includes light waves, radio waves, infrared radiation, ultraviolet radiation, X rays, and gamma rays.

Radio astronomy is the study of celestial objects by means of the radio waves they emit. Radio waves are the longest form of electromagnetic radiation. Some of these waves measure up to 6 miles (more than 9 kilometers) from peak to peak. Objects that appear very dim or are invisible to our eye may have very strong radio waves.