Karl Guthe Jansky
Karl Guthe Jansky | |
---|---|
Oklahoma, U.S. | |
Died | February 14, 1950 Red Bank, New Jersey, U.S. | (aged 44)
Nationality | American |
Known for | Radio astronomy |
Scientific career | |
Fields | Physics Radio astronomy |
Karl Guthe Jansky (October 22, 1905 – February 14, 1950) was an American physicist and radio engineer who in April 1933 first announced his discovery of radio waves emanating from the Milky Way in the constellation Sagittarius. He is considered one of the founding figures of radio astronomy.[1]
Early life
Karl Guthe Jansky was born 1905 in what was then the
Karl Jansky's mother, born Nellie Moreau, was of French and English descent. Karl's brother Cyril Jansky Jr., who was ten years older, helped build some of the earliest radio transmitters in the country, including 9XM in Wisconsin (now WHA of Wisconsin Public Radio) and 9XI in Minnesota (now KUOM).[2]
Karl Jansky attended college at the
Radio astronomy
At Bell Telephone Laboratories, Jansky built a
After recording signals from all directions for several months, Jansky eventually categorized them into three types of static: nearby thunderstorms, distant thunderstorms, and a faint static or "hiss" of unknown origin. He spent over a year investigating the source of the third type of static. The location of maximum intensity rose and fell once a day, leading Jansky to initially surmise that he was detecting radiation from the Sun.
After a few months of following the signal, however, the point of maximum static moved away from the position of the Sun. Jansky also determined that the signal repeated on a cycle of 23 hours and 56 minutes. Jansky discussed the puzzling phenomena with his friend, astrophysicist Albert Melvin Skellett, who pointed out that the observed time between the signal peaks was the exact length of a sidereal day; the time it took for "fixed" astronomical objects, such as a star, to pass in front of the antenna every time the Earth rotated.[5] By comparing his observations with optical astronomical maps, Jansky concluded that the radiation was coming from the Milky Way and was strongest (7:10 p.m. on September 16, 1932) in the direction of the center of the galaxy, in the constellation of Sagittarius.
Jansky announced his discovery at a meeting in Washington D.C. in April 1933 to a small audience who could not comprehend its significance.
If the radio sources were from the stars, the Sun should also be producing radio noise, but Jansky found that it did not. In the early 1930s, the Sun was at an inactive phase in its sunspot cycle. In 1935 Jansky made the suggestion that the strange radio signals may be produced from interstellar gas, in particular, by "thermal agitation of charged particles."[5] Jansky accomplished these investigations while still in his twenties with a bachelor's degree in physics.
Jansky wanted to further investigate the Milky Way radio waves after 1935 (he called the radiation "Star Noise" in the thesis he submitted to earn his 1936 University of Wisconsin Masters degree),[9][10] but he found little support from either astronomers, for whom it was completely foreign, or Bell Labs, which could not justify, during the depression, the cost of research on a phenomenon that did not significantly affect trans-Atlantic communications systems.
Follow-up
Several scientists were interested in Jansky's discovery, but radio astronomy remained a dormant field for several years, due in part to Jansky's lack of formal training as an astronomer. His discovery had come in the midst of the Great Depression, and observatories were wary of taking on any new and potentially risky projects.[11]
Two men who learned of Jansky's 1933 discovery were of great influence on the later development of the new study of radio astronomy: one was Grote Reber, a radio engineer who singlehandedly built a radio telescope in his Illinois back yard in 1937 and did the first systematic survey of astronomical radio waves. The second was John D. Kraus, who, after World War II, started a radio observatory at Ohio State University and wrote a textbook on radio astronomy, long considered a standard by radio astronomers.[11]
"In 1930 essentially all that we knew about the heavens had come from what we could see or photograph. Karl Jansky changed all that. A universe of radio sounds to which mankind had been deaf since time immemorial now suddenly burst forth in full chorus." –John D. Krauss [4]
Death and legacy
Jansky was a resident of Little Silver, New Jersey, and died at age 44 in a Red Bank, New Jersey, hospital (now called Riverview Medical Center) due to a heart condition.[12]
"Had Jansky not died at a very early age, he would undoubtedly have been awarded the Nobel Prize. His serendipitous discovery gave birth to a new branch of astronomy, radio astronomy." –William A. Imbriale [13]
In honor of Jansky, the unit used by radio astronomers for the
A full-scale replica of Jansky's original rotating telescope is located on the grounds of the Green Bank Observatory (38°25′53.9″N 79°48′58.5″W / 38.431639°N 79.816250°W, formerly an NRAO site) in Green Bank, West Virginia, near a reconstructed version of Grote Reber's 9-meter dish.
In 1998, the original site of Jansky's antenna (40°21′54.5″N 74°09′48.9″W / 40.365139°N 74.163583°W) at what is now the
Jansky noise is named after Jansky, and refers to
Asteroid
.Selected writings
- Jansky, Karl Guthe (December 1932). "Directional studies of atmospherics at high frequencies". S2CID 51660959.
- Jansky, Karl Guthe (July 8, 1933). "Radio waves from outside the solar system". Nature. 132 (3323): 66. S2CID 4063838.
- Jansky, Karl Guthe (October 1933). "Electrical disturbances apparently of extraterrestrial origin". Proc. IRE. 21 (10): 1387. S2CID 47549559. along with an explanatory preface by W.A. Imbriale, Introduction To "Electrical Disturbances Apparently Of Extraterrestrial Origin".
- Jansky, Karl Guthe (December 1933). "Electrical phenomena that apparently are of interstellar origin". Popular Astronomy. 41: 548. Bibcode:1933PA.....41..548J.
- Jansky, Karl Guthe (October 1935). "A note on the source of interstellar interference". Proc. IRE. 23 (10): 1158. S2CID 51632813.
- Jansky, Karl Guthe (December 1937). "Minimum noise levels obtained on short-wave radio receiving systems". Proc. IRE. 25 (12): 1517. S2CID 51660095.
See also
- Reber Radio Telescope
- Astronomical radio source
- Radio Astronomy
References
- ISBN 978-0-00-716221-5, p. 406
- ^ "Cyril M. Jansky, Jr". January 20, 2016.
- ^ a b Serendipitous Discoveries in Radio Astronomy: Proceedings of a Workshop held at the National Radio Astronomy Observatory, Green Bank, West Virginia on May 4, 5, 6, 1983; Honoring the 50th Anniversary Announcing the Discovery of Cosmic Radio Waves by Karl G. Jansky on May 5, 1933. Edited by K. Kellermann and B. Sheets (1983) 321pp
- ^ a b c Kraus, John (Fall 1981). "The First 50 Years of Radio Astronomy, Part 1: Karl Jansky and His Discovery of Radio Waves from Our Galaxy". North American AstroPhysical Observatory (NAAPO). Cosmic Search, Vol. 3, No. 4. Retrieved September 21, 2021.
In 1930 essentially all that we knew about the heavens had come from what we could see or photograph. Karl Jansky changed all that. A universe of radio sounds to which mankind had been deaf since time immemorial now suddenly burst forth in full chorus.
- ^ a b World of Scientific Discovery on Karl Jansky. Retrieved April 9, 2010.
- ISBN 978-0-521-61602-7
- New York Times. Retrieved August 14, 2008.
- S2CID 4063838.
- ^ "Karl Jansky". MagLab. National High Magnetic Field Laboratory. Retrieved June 17, 2022.
- ^ "Jansky, Karl (1905–1950)". Encyclopedia.com. May 17, 2018. Retrieved June 17, 2022.
- ^ a b Ghigo, F (2003). "Karl Jansky and the Discovery of Cosmic Radio Waves". nrao.edu. National Radio Astronomy Observatory. Retrieved October 1, 2021.
- ^ "Karl G. Jansky, 44, Authority in Radio; Bell Laboratories Engineer Dies–Discovered Waves of Extraterrestrial Origin". The New York Times. February 15, 1950. Retrieved May 7, 2010.
Karl Guthe Jansky of 57 Silverton Avenue, Little Silver, N.J., radio research engineer with the Bell Telephone Laboratories since 1928, who discovered radio waves of extraterrestrial origin in 1933 died yesterday in the Riverside [sic] Hospital, Red Bank, N.J., of a heart malady.
- .
Had Jansky not died at a very early age, he would undoubtedly have been awarded the Nobel Prize. His serendipitous discovery gave birth to a new branch of astronomy, radio astronomy.
- ^ "Jansky Fellowship".
- ^ "Jansky Prize".
- ^ "VLA Rededication".
- ^ "Detective Work Leads to Monument Honoring the Father of Radio Astronomy". Bell Labs. June 3, 1998. Archived from the original on January 3, 2020.
- ^ Historical Marker Database: Karl Jansky Radio Astronomy Monument
- ISBN 978-3-540-29925-7.
- Sullivan, W. T., ed. (1984), The Early Years of Radio Astronomy: Reflections Fifty Years After Jansky's Discovery, Cambridge University Press, ISBN 978-0-521-61602-7. In particular Chap.1 by Sullivan, "Karl Jansky and the discovery of extraterrestrial radio waves," pp. 3–42.
- Sullivan, W. T. (2009), Cosmic Noise: A History of Early Radio Astronomy, Cambridge University Press. In particular Chap. 2.
External links
- My Brother Karl Jansky and His Discovery of Radio Waves from Beyond the Earth
- Ghigo, F. (February 7, 2006). "Karl Jansky and the Discovery of Cosmic Radio Waves". National Radio Astronomy Observatory.
- Serendipitous Discoveries in Radio Astronomy: Proceedings of a Workshop held at the National Radio Astronomy Observatory, Green Bank, West Virginia on May 4, 5, 6,1983; Honoring the 50th Anniversary Announcing the Discovery of Cosmic Radio Waves by Karl G. Jansky on May 5, 1933. Edited by K. Kellermann and B. Sheets (1983) 321pp
- Accompanying 3 photos: from 1962, from c.1960 (with Grote Reber), and one of Karl Jansky, another astronomy pioneer, from c.1930.
- Encyclopedia of Oklahoma History and Culture – Jansky, Karl
- Detective Work Leads to Monument Honoring the Father of Radio Astronomy — Radio Astronomy Celebration at NOKIA Bell Labs