Quasars are compact extragalactic objects, not much larger than our Solar System, each of which emits more energy than a hundred supergiant galaxies. Some have nearly 1,000 times the luminosity of a bright supergiant galaxy. They appear starlike in telescopes but were discovered, in 1963, because of their radio emissions. Thousands of quasars have now been identified and we know that most of their energy is in the infrared, although they are also bright optical and x-ray sources. Only about 10% emit powerful radio energy.

Because of the high redshift found in the spectra of quasars, we know that they are receding from us at a very high percentage of the speed of light. This means that they are the most distant and therefore the youngest extragalactic objects that we observe.

The bright "star" near the center of this image is actually quasar 3C 273, located 3 billion light years away. It is the brightest of all known quasars and can be seen in amateur telescopes as small as 8" if the seeing conditions are good.

This is a portion of the above image, color enhanced to show detail. The quasar 3C273 is arrowed. Note the faint optical jet to the lower right of the quasar. When this jet is imaged with radio telescopes, it can be seen to extend out of the lower right side to a distance of 150,000 light years. This tremendous jet radiates more light than our entire Milky Way Galaxy and over a million times as much radio energy. Quasar jets contain superheated gasses that are ejected at speeds close to the speed of light. These jets may emerge along the rotational axis of an accretion disk around a massive black hole at the center of the quasar.

This image shows the gravitational lens quasar 0957+561 which, at a distance of 5 billion light years, is the farthest object ever imaged at Kohl Observatory. What appears to be just two tiny dots is actually the light from a single very distant quasar. The light has been bent by the gravitational forces from a large foreground galaxy and its parent cluster of galaxies, acting like a giant lens in space. This "lens" also concentrates the light and magnifies the brightness of the distant quasar. In this manner, quasars act as background searchlights, allowing us to detect and study otherwise invisible matter.