A quasar is an extremely bright object in between far galaxies. Quasars are about the size of the solar system, but can be a trillion times brighter than the sun. Astronomers feel they are the furthest object detected in the universe. Some quasars are 16 billion light years away from the Earth. Determination of a quasar's distance is through its red shift.(see Space Encyclopedia) Quasars have very large red shifts.
Quasars give off enormous amounts of energy in the form of visible light, ultraviolet light, infrared rays, X-rays, and in some cases, radio waves. The light given off by quasars that is seen today is actually given off by the quasars billions of years age. It is for this reason that the study of quasars can provide information about early stages of the universe.