Jansky, Karl Guthe

Jansky, Karl Guthe,

1905–50, American radio engineer; b. Norman, Okla. After graduating (1927) from the Univ. of Wisconson, he joined the Bell Telephone Laboratories. While trying to determine the causes of radio communications static, Jansky discovered (1931) radio waves from extraterrestrial sources—a discovery that prompted the investigations of Gröte ReberReber, Gröte,
1911–2002, American radio engineer, b. Chicago, Ill. After graduating from the Armour Institute of Technology (now the Illinois Institute of Technology) in 1933, Reber worked for several radio manufacturers and radio stations.
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 and led to the development of the science of radio astronomyradio astronomy,
study of celestial bodies by means of the electromagnetic radio frequency waves they emit and absorb naturally. Radio Telescopes

Radio waves emanating from celestial bodies are received by specially constructed antennas, called radio telescopes,
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. By 1932 Jansky had concluded that the source of the interference was located in the direction of the center of the Milky Way galaxy.

Jansky's discovery was serendipitous. Not only was it by chance that he had chosen a frequency at which the galactic center emits large amounts of radiation and at which the earth's atmosphere is transparent, he also was working at a period of minimum sunspot activity which occurs only every 11 years. At sunspot maximum, the ionosphere would have blocked all extraterrestrial radio waves at the 20 MHz frequency, and signals from the Milky Way would not have been detected.

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Jansky, Karl Guthe

(1905–50) radio astronomer; born in Norman, Okla. He initiated the field of radio astronomy when he detected radio waves coming from various places in the Milky Way while investigating short-wave radio telephone interference for Bell Laboratories (1928–31). His published papers (1933–35) established that this "star-noise" was radiation originated in distant space. This led to investigations that have taken astronomy billions of light years beyond the capability of optical telescopes. The jansky, a unit of radio emission strength, honors his work.
The Cambridge Dictionary of American Biography, by John S. Bowman. Copyright © Cambridge University Press 1995. Reproduced with permission.