Non-optical telescopes examine light from the sky at wavelengths other than those of visible light. Many different types exist to study incoming radio waves, microwaves, infrared and near-infrared rays, ultraviolet rays, X-rays and gamma rays.
Each section of the light spectrum has information that could not otherwise be detected. Radio astronomy, for example, has been used in the search for extraterrestrial life and was responsible for the discovery of pulsars. Microwave astronomy detected the residual heat from the Big Bang. Other telescopes abandon the electromagnetic spectrum entirely, focusing instead on detecting neutrinos or charged particles in the solar wind. Each of these methods opens a fresh window on space studies and develops data that optical telescopes alone never could.