![](http://upload.wikimedia.org/wikipedia/commons/1/11/SDSS_image_of_quasar_3C273.jpg)
A quasar is an extremely luminous active galactic nucleus (AGN), in which a supermassive black hole with mass ranging from millions to billions of times the mass of the Sun is surrounded by a gaseous accretion disk. Sloan Digital Sky Survey image of quasar 3C 273, illustrating the object's star-like appearance. The quasar's jet can be seen extending downward and to the right from the quasar.