A space telescope or space observatory is a telescope located in outer space to observe distant planets, galaxies and other astronomical objects. Space telescopes avoid the filtering of ultraviolet frequencies, X-rays and gamma rays; the distortion (scintillation) of electromagnetic radiation; as well as light pollution which ground-based observatories encounter.

Suggested by Lyman Spitzer in 1946, the first operational space telescopes were the American Orbiting Astronomical Observatory, OAO-2 launched in 1968, and the Soviet Orion 1 ultraviolet telescope aboard space station Salyut 1 in 1971.

Space telescopes are distinct from Earth imaging satellites, that point toward Earth for satellite imaging, applied for espionage, weather analysis and other types of information gathering.

Space observatories are divided into two types: Astronomical survey satellites to map the entire sky, and satellites which focus on selected astronomical objects or parts of the sky and beyond.

 

Note:   The above text is excerpted from the Wikipedia article Space telescope, which has been released under the GNU Free Documentation License.