<P> In the 1980s, unified models were developed in which quasars were classified as a particular kind of active galaxy, and a consensus emerged that in many cases it is simply the viewing angle that distinguishes them from other active galaxies, such as blazars and radio galaxies . </P> <P> The mechanism of brightness changes probably involves relativistic beaming of astrophysical jets pointed nearly directly toward Earth . The highest redshift quasar known (as of June 2011) is ULAS J1120 + 0641, with a redshift of 7.085, which corresponds to a comoving distance of approximately 29 billion light - years from Earth (these distances are much larger than the distance light could travel in the universe's 13.8 billion year history because space itself has also been expanding). </P> <P> More than 200,000 quasars are known, most from the Sloan Digital Sky Survey . All observed quasar spectra have redshifts between 0.056 and 7.085 . Applying Hubble's law to these redshifts, it can be shown that they are between 600 million and 28.85 billion light - years away (in terms of comoving distance). Because of the great distances to the farthest quasars and the finite velocity of light, they and their surrounding space appear as they existed in the very early universe . </P> <P> The power of quasars originates from supermassive black holes that are believed to exist at the core of most galaxies . The Doppler shifts of stars near the cores of galaxies indicate that they are rotating around tremendous masses with very steep gravity gradients, suggesting black holes . </P>

What is the smallest redshift measure for a quasar
find me the text answering this question