Quasars

Quasars is a very energetic and distant active galactic nucleus. These mysterious starlike objects shine from the outermost limits of the universe, helping scientists learn about the earliest stages of existence. We’ve since learned that a quasar is actually a black hole at the center of a huge, distant galaxy. Perhaps more interesting, quasars give off 1,000 times more energy than the entire Milky Way galaxy.

Quasars show a very high redshift, which is an effect of the expansion of the universe between the quasar and the Earth. When combined with Hubble's law, the implication of the redshift is that the quasars are very distant—and thus, it follows, very ancient objects.

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 proper distance). Because of the great distances to the farthest quasars and the finite velocity of light, we see them and their surrounding space as they existed in the very early universe. Read this more. 

bY : Nella Faras