ESO Astronomical Glossary - Q
Quasi-Stellar Radio source (see Quasar).
Quasars, named after 'quasi-stellar radio object', are highly energetic active galactic nuclei and represent some of the most luminous objects in the Universe. Quasars were first detected in 1963 by astronomers Maarten Schmidt and Allen R. Sandage. They are also known as 'quasi-stellar objects' or QSOs. Because of their distance from us they appear as point sources, which led to the name 'quasi-stellar'.