Karl Jansky was a radio engineer who made a groundbreaking discovery in 1933, he detected radio waves coming from outer space. Jansky was working for the Bell Telephone Laboratories when he made his discovery. He had been tasked with investigating sources of interference that were disrupting the reception of transatlantic radio communications in order to optimize transmission of signals. To do this, he built a special antenna that was sensitive to radio waves at short wavelengths (14.5m). The antenna was a 30’ Modified Bruce Array sensitive to frequency 20.5 Mhz. One would have mistaken it for a kid’s playground merry-go-round for its “un-Antenna-like” appearance. It’s frame of wood and copper pipes, rotated on 4 Ford model-T tires allowing for a large area sky survey and providing directionality to locate signal sources.
For more than two years as he was scanning the skies, Jansky noticed that there was a strong source of radio waves coming from a specific direction in the sky. After carefully eliminating possible local sources, he concluded the source was not a man-made object. The source of the hiss did not change position with the rotation of the Earth. Jansky realized that he had discovered radio waves emitted from an extraterrestrial source. He would pin the hiss coming from the direction of Sagittarius, a location from close to the center of our galaxy.
He published these exciting results in a radio engineers journal and he would be featured on the front page of New York Times, May 5, 1933. The result did not stir the Astronomy community a lot. It would take another radio Engineer, Grote Reber, to pursue and confirm Jansky’s discovery more meticulously. By building a bigger telescope he would survey the sky over several wavelengths confirming Jansky’s observations. In 1944 Reber published the 160MHz contour map of the northern sky and his correspondence with astronomers would usher the new era of radio astronomy.
Jansky's discovery was a major milestone in the field of astronomy, as it opened up a whole new way of studying the universe. Radio waves, unlike visible light, can pass through clouds of dust and gas that block our view of the cosmos. This means that radio telescopes can detect objects and phenomena that are invisible to optical telescopes. Objects such as pulsars and quasars were discovered from their radio emissions. Karl Jansky's discovery of radio waves emitted from outer space was a groundbreaking moment in the history of astronomy and opened up a new way for us to observe the Universe.