astronomy, observes wavelengths of light from approximately 400 to 700 nm. Positioning an optical telescope in space eliminates the distortions and limitations that hamper that ground-based optical telescopes (see Astronomical seeing), providing higher resolution images. Optical telescopes are used to look at planets, stars, galaxies, planetary nebulae and protoplanetary disks, amongst many other things. Infrared and submillimetre Infrared light is of lower energy than visible light, hence is emitted by sources that are either cooler, or moving away from the observer (in present context: Earth) at high speed. As such, the following can be viewed in the infrared: cool stars (including brown dwarves), nebulae, and redshifted galaxies. Microwave Microwave space telescopes have primarily been used to measure cosmological parameters from the Cosmic Microwave Background. They also measure synchrotron radiation, free-free emission and spinning dust from our Galaxy, as well as extragalactic compact sources and galaxy clusters through the Sunyaev-Zel'dovich effect. Radio As the atmosphere is transparent for radio waves, radio telescopes in space are most useful for Very Long Baseline Interferometry: doing simultaneous observations of a source with both a satellite and a ground-based telescope and by correlating their signals to simulate a radio telescope the size of the separation between the two telescopes. Typical targets for observations include supernova remnants, masers, gravitational lenses, and starburst galaxies. Particle detection Spacecraft and space-based modules that do particle detection, looking for cosmic rays and electrons. These can be emitted by the sun (Solar Energetic Particles), our galaxy (Galactic cosmic rays) and extragalactic sources (Extragalactic cosmic rays). There are also Ultra-high-energy cosmic rays from active galactic nuclei, those can be detected by ground-based detectors via their particle showers. Gravitational waves A type of telescope that detects gravitational waves; ripples in space-time generated by colliding neutron stars or black holes. To be launched See also List of proposed space observatories List of heliophysics missions List of solar telescopes Lists of telescopes Lists of spacecraft Great Observatories program References External links Space telescopes telescopes Telescopes