In visible light, 3C273 is the brightest quasar in our sky. Its name signifies that it was the 273rd object of the 1959 Third Cambridge Catalog of Radio Sources (3C). Exactly 50 years ago – on March 16 1963 – astronomer Maarten Schmidt of Caltech had a revelation about the nature of 3C273 that changed the way people think about the universe.
This is 3C273. It changed our thinking about the universe.
March 16, 2013 is the 50th anniversary of the revelation that quasars are both very distant and very luminous – and therefore must be exceedingly powerful.