Radio telescopes and optical telescopes use different types of electromagnetic radiation to observe the universe. Radio telescopes detect radio waves, which have longer wavelengths and lower frequencies than visible light, while optical telescopes detect visible light, which has shorter wavelengths and higher frequencies than radio waves.
Radio waves can pass through dust and gas clouds, which makes them useful for studying objects that are obscured by these materials. Radio telescopes are also able to detect emissions from cold objects such as interstellar gas clouds, which emit very little visible light. In contrast, optical telescopes are sensitive to visible light, which provides information about the temperature, composition, and movement of objects in space. Optical telescopes are also able to capture images of celestial objects, which can reveal details about their structure and surface features.
Overall, radio telescopes and optical telescopes are complementary tools for studying the universe, each providing unique information about the objects they observe. Radio telescopes are used to study radio emissions from celestial objects, while optical telescopes are used to study visible light emissions.