Mysterious objects emitting radio waves were first identified in 1963 by radio astronomers who called them quasi-stellar radio sources, or quasars. Their origin was debated for a long time, but quasars are now thought to be extremely bright discs of matter swirling around supermassive black holes at the centres of distant galaxies.
Quasars are often so bright that they drown out any light from the galaxies surrounding them, giving them a star-like appearance from our perspective on Earth.
Image: A 100,000 light-year-long stream of particles jets from a quasar (credit: NASA/JPL-Caltech/Yale Univ.)
Dr John Beckman explains to Patrick Moore that quasars seem to be caused by material such as stars and gas descending into black holes at an intermediate stage in their development.
Patrick Moore and Dr John Beckman discuss the discovery of 3C 273 - the first object to be identified as a quasar.
Patrick Moore talks to Dr Alan Wright about the first identification of a quasar, on the basis of measurements made at the Parkes Observatory, New South Wales.
Astronomers investigating quasars in the late 1960s did not know what caused them. Quasars are now thought to be extremely bright discs of matter swirling around supermassive black holes at the centres of distant galaxies.
Sir Patrick Moore listens to pulsars at Jodrell Bank Observatory.
A quasi-stellar radio source ("quasar", /ˈkweɪzɑr/) is a very energetic and distant active galactic nucleus. Quasars are extremely luminous and were first identified as being high redshift sources of electromagnetic energy, including radio waves and visible light, that were point-like, similar to stars, rather than extended sources similar to galaxies.
While the nature of these objects was controversial until as recently as the early 1980s, there is now a scientific consensus that a quasar is a compact region in the center of a massive galaxy surrounding its central supermassive black hole. Its size is 10–10,000 times the Schwarzschild radius of the black hole. The quasar is powered by an accretion disc around the black hole.
This entry is from Wikipedia, the user-contributed encyclopedia. If you find the content in the 'About' section factually incorrect, defamatory or highly offensive you can edit this article at Wikipedia.
BBC © 2013 The BBC is not responsible for the content of external sites. Read more.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.
