Finding the Fastest Galaxy: 76,000 Miles per Second

The tiny spot of light known as 3C-147 looked no different from the countless millions of dim stars that can be picked out by the giant, 200-in. telescope on top of Mount Palomar. But when astronomers from Caltech's radio observatory reported that their 90-ft. dish antennas were picking up powerful radio waves from 3C-147's faint gleam, Palomar's men decided to make a closer examination.

Astronomer Maarten Schmidt focused Palomar's big scope on the strange source of electromagnetic noise. By using very long exposures, he photographed 3C-147's spectrum--the rainbow of lines and hues that give away the chemical secrets of their source. The pictures brought out oxygen and neon lines that were shifted farther toward the red end of the spectrum than any such lines ever photographed before. Since red shift is caused by motion, 3C-147, Schmidt decided, must be speeding away from the earth at 76,000 miles per second, almost half the speed of light. He had taken a picture of the fastest object known to man.

It was also, clearly, the most distant. Since the universe is expanding, its parts that are moving fastest must be farthest away. Measured by Hubble's constant, which translates speed into distance, 3C-147 is about 4 billion light-years away from the earth. But Dr. Ira Bowen, director of Mount Wilson and Palomar observatories, prefers to say "several billion" lightyears; he suspects that Hubble's constant may not be accurate over such enormous distances.

Dr. Bowen is reasonably certain that 3C-147 is a galaxy that exploded several billion years ago, giving more light than 100 normal galaxies. Along with its light, its blowup sent out powerful radio waves, probably generated by high-speed electrons moving in a magnetic field.

The Palomar telescope can photograph swarms of galaxies out at the limit of its vision, but most of them look like blurry blobs, and they are much too faint for their spectra to be photographed. Only exploding galaxies 100 times brighter than normal give such meaningful information about what was happening billions of years ago in the depths of space. A dozen such galaxies have been found so far, and astronomers are confident that many more can be found by the kind of radio scouting that stirred up interest in 3C-147. The spectrum of their ancient light may tell whether the universe is still being created, and whether it has limits in either space or time.

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