The detection of the first radio waves from outer space is credited to Karl Jansky, an American physicist and engineer. In the early 1930s, Jansky was working for Bell Telephone Laboratories, investigating sources of interference that could affect long-distance telephone communication.
As part of his work, Jansky constructed a specialized antenna system known as a directional antenna. This antenna was designed to receive radio waves at a wavelength of approximately 14.6 meters (20.5 MHz). By rotating the antenna, Jansky was able to determine the direction from which the radio waves were coming.
During his observations, Jansky noticed a puzzling source of interference that appeared as a steady hiss in all directions. After careful analysis, he determined that this noise was not originating from man-made sources, but rather from beyond Earth. Jansky had unintentionally discovered radio waves emanating from the Milky Way galaxy.
Jansky published his findings in 1933, presenting the first documented evidence of extraterrestrial radio waves. His discovery marked the birth of radio astronomy, a new field of study that focuses on the detection and analysis of radio waves emitted by celestial objects. Jansky's pioneering work laid the foundation for future advancements in radio astronomy and our understanding of the universe.