page_title: Telescope
section_title: Other types of telescopes
hierarchical_section_title: Telescope / Types / Other types of telescopes
context_page_description: A telescope is an optical instrument using lenses, curved mirrors, or a combination of both to observe distant objects, or various devices used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. The first known practical telescopes were refracting telescopes invented in the Netherlands at the beginning of the 17th century, by using glass lenses. They were used for both terrestrial applications and astronomy.
  The reflecting telescope, which uses mirrors to collect and focus light, was invented within a few decades of the first refracting telescope. In the 20th century, many new types of telescopes were invented, including radio telescopes in the 1930s and infrared telescopes in the 1960s. The word telescope now refers to a wide range of instruments capable of detecting different regions of the electromagnetic spectrum, and in some cases other types of detectors.
context_section_description: Astronomy is not limited to using electromagnetic radiation. Additional information can be obtained by detecting other signals, with detectors analogous to telescopes. These are:
  Cosmic-ray telescopes detect cosmic rays and usually consist of an array of different detector types spread out over a large area.
  Energetic neutral atom instruments study the magnetosphere of various bodies by detecting fast moving electrically neutral atoms created by the solar wind.
  Neutrino detectors, the equivalent of neutrino telescopes, used for neutrino astronomy. They consist of a large mass of water and ice, surrounded by an array of sensitive light detectors known as photomultiplier tubes. Originating direction of the neutrinos is determined by reconstructing the path of secondary particles scattered by neutrino impacts, from their interaction with multiple detectors.
  Gravitational-wave detectors, the equivalent of gravitational wave telescopes, are used for gravitational-wave astronomy. Gravitational waves, caused by violent collisions in space, are detected by extremely precise measurements of the change in length of large earth-bound structures.
caption: The reflectors of HEGRA detect flashes of light in the atmosphere, thus detecting high energy particles
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