  Quasars are among the furthest things we can see. They seem to be anywhere from 12 to 15 billion light years away, and moving away from us at speeds close to the speed of light. This means we are seeing quasars the way they were 12-15 billion years ago! This is only a few billion years after the 'Big Bang', so quasars, whatever they are, existed near the beginning of the universe. Quasars appear in our biggest telescopes as very faint stars...but since they are so far away, they must in fact be incredibly bright. It is believed that they are young galaxies, that contain massive black holes at their centres. As dust, gas, and stars get pulled into this giant black hole, a quasar beams brightly with the radiation emitted...brighter than a hundred galaxies! How quasars formed, and how they operate, is still uncertain. Since they are at the limit of the observable universe, only the largest or most sensitive telescopes can be used to study them. The study of quasars, and determining a theory that explains their formation and characteristics, is an important area of modern astrophysics research. |