Radio astronomy is a subfield of astronomy that studies celestial objects and phenomena by detecting and analyzing the radio waves they emit or reflect. Radio waves have a lower frequency and longer wavelength than visible light, which makes them useful for studying objects like galaxies, stars, and planets that may not emit enough or any visible light. Radio telescopes are used to collect radio waves, which can be analyzed to gather information about the object emitting them, such as its temperature, composition, and motion. Radio astronomy has contributed significant discoveries to our understanding of the universe, including the discovery of pulsars, quasars, and the cosmic microwave background radiation.