Jansky , Karl Guthe

(1905–1950) American radio engineer

Born in Norman, Oklahoma, Jansky was educated at the University of Wisconsin and started his career with the Bell Telephone Laboratories in 1928. He was given the task of investigating factors that could interfere with radio waves used for long-distance communication. He designed a linear directional antenna, which, mounted on wheels from a Model T Ford, could scan the sky. He identified all the sources of interference, such as thunderstorms, except for one weak emission. This he found to be unconnected with the Sun and in 1931 he discovered that the radio interference came from the stars.

Jansky published his findings in the Proceedings of the Institute of Radio Engineers in December 1932, the date that marks precisely the beginnings of radio astronomy. In his paper Jansky made two astute comments: he suggested that the radio emission was somehow connected with the Milky Way and that it originated not from the stars but from interstellar ionized gas. He did not pursue his suggestions and it was left to Grote Reber, the amateur astronomer, to keep the subject alive until it developed into a major research field after 1945.

The unit of radio-wave emission strength was named the jansky in his honor.