Karl Jansky an American engineer and pioneer of Radio Astronomy was born on 22nd October 1905 in Norman, Okla, United States. Also known as father of radio astronomy; whose discovery of radio waves from an extraterrestrial source inaugurated the development of radio astronomy, a new science that from mid 20th century greatly extended the range of astronomical observations. On the birth-anniversary of Karl Jansky here’s an article diving into his scientific life and contribution to an extra-ordinary impact on world of astronomy.
Karl Jansky was third among six children; son of Cyril Jansky, an electrical engineering professor at the University of Wisconsin who endured a rigid love for physics in his three sons. He was named after physicist Karl Guthe whom his father had worked for earlier in his career. Karl Jansky earned his degree in physics from the University of Wisconsin. He joined the research staff of Bell Telephone Laboratories in year 1928. But Bell labs were initially reluctant to hire him as he was diagnosed with chronic kidney disease in college. Cyril Janksy Jr. an electrical engineer like his father and a former Bell Labs staff member who helped build some of the earliest radio transmitters in U.S interceded on his behalf.
He was assigned the challenging task! The Bell Labs wanted to investigate atmospheric and ionospheric properties using ‘short waves’ (10- 20 meters) for use in trans-Atlantic radio telephone service and as a radio engineer Jansky was assigned to investigate and study intermittent static sources that might be interfering with radio voice transmission. Now Jansky had to design and build special instruments for that purpose; a large directional antenna system mounted on a motor-driven turntable that rotated through 360º about a central vertical axis, riding on a circular track on the wheels of a Model-T Ford. Dubbed as “Jansky’s merry-go-round.“
After rigorous analysis of data which were collected over many tedious months – Jansky identified three types of static. A weak signal caused by distant thunder storms, a more powerful burst due to local thunderstorm and third type which produced a steady hiss. The third he described as being “composed of very steady hiss static the origin of which is not yet known.” His careful wording came at the advice of his supervisor, who cautioned him against making over-bold claims. But Jansky suspected that the signal originated in the center of Milky Way galaxy, making it first known detection of extraterrestrial radio signals. In year 1933 a journal article “Electrical disturbances apparently of extraterrestrial origin” he clearly refered these electromagnetic waves detected causing the hiss belongs to an unknown origin.
The reasonings were simple; he studied that the third type of static for over a year and noted that it rose and fell once a day. The very first conclusion was that it was radiation from sun but after few months the brightest point of the signal moved away from the sun’s position, moreover the rise and fall did not repeat exactly every 24 hours but every 2 hours and 56 minutes – a property of fixed stars and other celestial objects beyond our solar system. His strongest opinion based on this conclusion was that the most likely source of the radiation was the center of the Milky Way, where the signal was strongest in the constellation of Sagittarius.
The result was not one, but three published papers, including “Electrical disturbances apparently of extraterrestrial origin” (as mentioned previously), which he presented at a meeting of the International Scientific Radio Union in April 1933. This led to high-profile news story in The New York Times on May 5th 1933, trumpeting his discovery and the University awarded Jansky his master’s degree based on the three papers. To continue investigating these mysterious cosmic signals he wanted to build a 30 meter dish antenna for that purpose. But applied research was the center of focus of Bell Labs. Since he showed that hissing static were not problematic for transatlantic communication, they judged the project complete and assigned Jansky another project. He remained at Bell Labs for the rest of his career, toiling in relative obscurity despite pioneering a new field of science, although he was elected as a fellow of the Institute of Radio Engineers in 1948. But this new field of science didn’t emerge overnight, the dire economy and Jansky’s lack of professional standing as an astronomer dissuaded various observatories from investing in future research. The radio astronomy got a boost during World War II after development of radar, astronomer named John Kraus was able to start a radio observatory at Ohio State University. He eventually wrote a textbook that became bible for the radio astronomers. Radio astronomy by year 1964 became an established branch – the year Arno Penzia and Robert Wilson used a giant horn antenna to discover the cosmic microwave background radiation.
Jansky died in year 1950 at the age of 44 due to massive stroke stemming from his kidney disease. Jansky’s work would most likely have won a Nobel Prize. Today the “Jansky” is the unit of measurement for radio wave intensity (flux density), a crater on the moon named after him, and the monument in his honor at the New Jersey site of his pivotal experiment.