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On April 27, 1933, at the annual meeting of the US National Committee for the International Union of Radio Science (URSI) in Washington DC, less than 50 years after Heinrich Hertz had demonstrated the propagation and detection of radio waves, Karl Guthe Jansky reported that he had detected radio signals from the center of the Milky Way. Jansky had no background in astronomy and was not searching for extraterrestrial radio signals, but was working for the AT&T Bell Laboratories to locate the source of interference to transatlantic telephone circuits. Only about 30 people were present to hear Jansky’s dramatic announcement, one that would change the course of twentieth-century astronomy and lead to at least eight future Nobel Prizes. Although Jansky’s discovery aroused great public interest, nearly two decades would pass before the American scientific community became sufficiently interested to invest in this emerging new field of astronomy. By that time, scientists trained in wartime radio and radar technology, primarily in Britain and Australia, had made a series of spectacular astronomical discoveries, and the USA was in danger of falling behind in this rapidly growing field, with obvious implications for technology, for military use, and for national prestige.

Prior to Jansky’s discovery, astronomical research was confined to the narrow optical window between 4000 and 7000 Angstroms (400–700 nm), only about a factor of two in wavelength. With the spectacular postwar development in electronic instrumentation and the resulting march toward shorter and shorter wavelengths, radio observations today cover the broad spectrum between less than 1 mm to more than 10 m, a range of about 105 in wavelength. The subsequent rapid growth of space programs extended astronomers access to the entire electromagnetic spectrum from the infrared to the ultraviolet, X-ray, and gamma-ray, all of which are obscured by the earth’s atmosphere. However, radio astronomy was the first outside the traditional optical window and resulted in the discovery of a wide range of previously unrecognized cosmic phenomena and many new previously unrecognized constituents of the universe. These included solar radio bursts, electrical storms on Jupiter, the Rh