- the branch of astronomy that utilizes extraterrestrial radiation in radio wavelengths rather than visible light for the study of the universe.
- a branch of astronomy in which a radio telescope is used to detect and analyse radio signals received on earth from radio sources in space
- The study of celestial objects by measurement of the radio waves they emit. Radio astronomy has enabled the detection and study of objects such as pulsars, quasars, radio galaxies, and other objects, some of which emit considerably less radiation at other wavelengths. Radio astronomy has contributed to the discovery of cosmic background radiation and has enhanced the understanding of solar activity and the structure of galaxies. See also radio telescope.