Astronomy: View from the Second Window

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Three centuries have passed since Galileo peered through his primitive telescope and first saw the moons of Jupiter and the golden crescent of Venus. Telescopes have been vastly improved since then, but men still study the stars through the same window opening on the universe. Their best lenses and most perfect mirrors work with visible light, and what cannot be brought into focus seemed forever beyond man's reach.

Suddenly the view has changed. The burgeoning science of radio astronomy has created a second window in the sky. And astronomers anxious to examine the far reaches of the celestial landscape are busily constructing the strange tools of their new trade. Odd shapes bulge above the horizon from Russia to Australia and all across the U.S. Great dishes of steel lacework sweep slowly across the sky; giant troughs rock like cradles; forests of poles and miles of wire stretch out in geometrical patterns. To avoid electrical interference, most of the radio telescopes hide away in mountain-ringed valleys, far from towns or well-traveled highways. But they are never far from the minds and hopes of scientists. Radio astronomy is barely 30 years old, and new discoveries are being recorded almost every day.

Ham Founder. The radio window was accidentally opened for the first time in 1932 by Karl Jansky. a Bell Telephone physicist who was studying the crackling static that can be so annoying in radio communications. During quiet periods, when no lightning flashes were disturbing the atmosphere, a faint hiss still sounded in his receiving apparatus. It seemed to rise and fall in strength as the earth turned. Jansky studied the hiss more carefully and found that its maximum strength came four minutes earlier each day. The time interval seemed significant.

Jansky knew that because of the earth's motion while it orbits the sun. the sidereal day, which measures the earth's rotation with respect to the stars, is four minutes shorter than the 24-hour solar day. He concluded that the hiss in his earphones was caused by radio waves from beyond the sun.

Jansky's work was wellpublicized, but it was done during the great Depression, when little cash was available to encourage scientific enterprise. Only a single radio ham, Grote Reber of Wheaton, Ill., followed Jansky's lead. Working alone, Reber built a dish antenna 31 ft. in diameter in his own backyard. With it he made the extraordinary discovery that the sky is full of radio stars that have nothing to do with ordinary stars. Reber had opened wide the radio window on the sky. His crude radio telescope, the world's first. now stands at the entrance of the National Radio Astronomy Observatory at Green Bank. W. Va.

Bulges & Squiggles. Soon after World War II. radio astronomy really got into high gear. Scientists in many lands, especially Britain and Australia, built improved radio telescopes to take advantage of the second window.

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