Investigating communications noise
After graduating from the University of Wisconsin in 1927 and spending another year in graduate study, Jansky joined Bell Laboratories. He used a rotating directional antenna in New Jersey to compare interference with direction and time.
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A signal from the Milky Way
Observations in 1930–1932 led him to trace an additional component of noise beyond the Solar System. In April 1933 he reported that this “star noise” came from the direction of the Galactic centre, turning an engineering interference problem into an astronomical observation.
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Engineering and commemoration
Later assigned mainly to defence and communications work, he contributed after the war to microwave repeaters and low-noise amplification. In 1973 the International Astronomical Union adopted jansky, abbreviated Jy, as the name of a flux-density unit.
References: [1]