US radio engineer who in 1932 discovered
that the Milky Way galaxy emanates radio waves; he did not follow up
his discovery, but it marked the birth of radioastronomy.
Jansky was born in Norman, Oklahoma, and studied at the University of
Wisconsin. In 1928 he joined the Bell Telephone Laboratories, New Jersey,
where he investigated causes of static that created interference on
Jansky noticed that the background hiss on a loudspeaker attached to
his specially built receiver and antenna system reached a maximum intensity
every 24 hours. It seemed to move steadily with the Sun but gained on
the Sun by four minutes per day. This amount of time correlates with
the difference of apparent motion, as seen on Earth, between the Sun
and the stars, so Jansky surmised that the source must lie beyond the
Solar System. By 1932, he had concluded that the source lay in the direction
of Sagittarius - the centre of our Galaxy.