Karl Guthe Jansky

Karl Guthe Jansky was an American physicist and radio engineer whose discovery of radio emission from the Milky Way helped establish radio astronomy.

Jansky's rotating antenna: A steerable antenna array Jansky built to locate sources of radio interference by recording signals as it rotated. Jansky used this instrument to distinguish a recurring sky signal from terrestrial interference.
Sidereal time: A timekeeping system based on Earth's rotation relative to distant stars rather than the Sun. The signal repeated on a sidereal schedule, pointing to a celestial source.
Radio astronomy: The study of celestial objects and phenomena through their radio-frequency emission. Jansky’s detection of galactic radio waves helped found this branch of astronomy.
Karl Guthe Jansky biography: The life and career of the American physicist and radio engineer who discovered radio emission from the Milky Way. His training and Bell Labs career explain how an engineering investigation became an astronomical discovery.
Jansky's discovery of radio waves from the Milky Way: The 1930s identification of radio emission from the direction of the Milky Way's center. This was Jansky’s decisive result and the basis of his place in radio astronomy.
Radio interference: Unwanted electromagnetic signals that disrupt the reception or interpretation of a desired radio signal. Jansky’s assignment was to identify interference, which initially obscured the cosmic signal.
Grote Reber: An American radio engineer who built an early radio telescope and mapped radio emission from the sky. Inspired by Jansky’s discovery, Reber pursued systematic radio observations.
Otto Struve: A Russian-American astronomer who directed the National Radio Astronomy Observatory and promoted radio astronomy. Struve helped secure institutional support for radio astronomy after Jansky’s initial discovery.
Jansky's radio source: A persistent radio signal Jansky traced to the direction of the Milky Way's center. Its sidereal-day recurrence showed that the signal came from beyond Earth.
Antenna: A conductor or array that transmits or receives electromagnetic waves. Jansky’s antenna converted incoming radio waves into signals he could record.

Linked from 6 pages