ultraviolet astronomy

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Study of cosmic ultraviolet emissions using artificial satellites. The USA launched a series of satellites for this purpose, receiving the first useful data in 1968. Only a tiny percentage of solar ultraviolet radiation penetrates the atmosphere, this being the less dangerous longer-wavelength ultraviolet radiation. The dangerous shorter-wavelength radiation is absorbed by gases in the ozone layer high in the Earth's upper atmosphere.

The US Orbiting Astronomical Observatory (OAO) satellites provided scientists with a great deal of information regarding cosmic ultraviolet emissions. OAO-1, launched in 1966, failed after only three days, although OAO-2, put into orbit in 1968, operated for four years instead of the intended one year, and carried out the first ultraviolet observations of a supernova and also of Uranus. OAO-3 (Copernicus), launched in 1972, continued transmissions into the 1980s and discovered many new ultraviolet sources. The International Ultraviolet Explorer, which was launched in January 1978 and ceased operation in September 1996, observed all the main objects in the Solar System (including Halley's comet), stars, galaxies, and the interstellar medium. FUSE (Far Ultraviolet Spectroscopic Explorer) is a collaboration between US universities and the Canadian and French space agencies, designed to observe at very short ultraviolet wavelengths. The Hubble Space Telescope observes at ultraviolet wavelengths as well as visible and infrared wavelengths. GALEX (Galaxy Evolution Explorer) is a US-French-Korean satellite launched in 2003 to study the UV emissions of galaxies.

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