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Raun Thorp, age 13, of Newport Beach, California, for her question:

What exactly is a quasar?

On a clear night, human eyes can behold about 2,000 stars in the en¬tire sky. Telescopes photograph millions more that are beyond our vision. On photographic plates, they look like bright pinpoints of light against the black background of outer space. In the 1960s, astronomers discovered that some of these pinpoints are not ordinary stars at all. They named them quasi stellar, or star like objects. Nowadays, everybody calls them quasars.

Astronomers are used to the amazing wonders of the heavens. But when quasars were discovered, they were almost too astonished to believe the evidence. For years they had mistaken these dots of light on their tele¬scope plates for ordinary stars. Meantime the great radio telescopes were scanning the skies for sources of distance radio emissions. And one of them zeroed in something that looked like an ordinary star.

The evidence seemed unbelieveable. For this star like object was emitting as much light and radio energy as our entire Galaxy, which has 100 billion stars. Naturally astronomers searched for more of these myster¬ious quasars    and during the 1960s they found about 200 of them.

Radio telescopes confirmed the fact that the amazing quasars emit as much energy as the average galaxy. Telescopes and other evidence verified this fact. Yet everything pointed to the fact that these dynamic power¬houses are cosmic midgets. Our Galaxy is estimated to be almost 100,000 light years from side to side, ten times larger than the largest quasars. The smallest quasars are 50 times smaller than one light year.

All the quasars so far discovered are at enormous distances    and racing out toward the edge of the known universe at breakneck speeds. One of them was clocked in 1965 and the evidence was breathtaking. This dynamic midget was at a distance of about 9 billion light years. And it was dashing away from us at a speed of 149,000 miles per second, which is pretty close to the speed limit of light.

Surely this quasar could claim the title of Farthest Object in the Known Universe. But not for long. Recently it lost its title to a quasar listed as OQ 172. The first evidence indicated that its distance from us is 12 billion light years. But this figure was soon revised. Astronomers now estimate the distance of the OQ 172 quasar to be ten billion light years.

The distances of the quasars are fascinating because they help astronomers to extend their view of the universe. At present, the outer limit of the universe is marked by OQ 172. But so far nobody is certain how such small objects can put forth as much dynamic energy as 100 billion suns. One theory suggests they may be collapsing galaxies. Amore recent theory suggests that perhaps a quasar is an infant galaxy, in the process of growing and forming billions of stars.

 

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