TRAC: Radio waves from space

Grote Reber in the foreground with his dish. The dish was removed from his backyard to Green Bank Observatory.

Grote Reber in the foreground with his dish. The dish was removed from his backyard to Green Bank Observatory.

Karl Guthe Jansky is generally considered to be the father of radio astronomy.

Born October 22, 1905, Jansky studied physics before joining Bell Telephone Laboratories in 1928.

At Bell, Jansky built an antenna designed to receive radio waves at a frequency of 20.5 MHz. It became known as "Jansky's merry-go-round".

At Bell, Jansky built an antenna designed to receive radio waves at a frequency of 20.5 MHz. It became known as "Jansky's merry-go-round".

He spent over a year investigating the source of a faint, steady “hiss”, leading Jansky to initially surmise that he was detecting radiation from the Sun.

After a few months, Jansky determined that the signal repeated on a cycle of 23 hours and 56 minutes, the period of the Earth's rotation relative to the stars (sidereal day) and he concluded that the radiation was coming from the Milky Way in the constellation of Sagittarius.

His discovery was published in Proc. IRE in 1933. 

This paper was re-printed in Proc. IEEE in 1984 for their centennial issue, where they note the research most likely would have won a Nobel Prize, had not the author died young.

Jansky wanted to follow up on this discovery and submitted a proposal to Bell Labs to build a 30 metre diameter dish antenna. 

Bell Labs, however, rejected his request for funding on the grounds that the detected emission would not significantly affect their planned transatlantic communications system. 

Jansky was re-assigned to another project and did no further work in the field of astronomy.

Grote Reber learned of Jansky's 1933 discovery and singlehandedly built a radio telescope in his Illinois back yard in 1937 and did the first systematic survey of astronomical radio waves.  

Reber was not a believer of the big bang theory; he believed that red shift was due to repeated absorption and re-emission or interaction of light and other electromagnetic radiations by low density dark matter, over intergalactic distances, and he published an article called "Endless, Boundless, Stable Universe", which outlined his theory.

Professor John D Kraus, who, after World War II, started a radio observatory at Ohio State University, wrote a textbook on radio astronomy, long considered a standard by radio astronomers.

Reber moved to Tasmania to further research his theory of the "Endless, Boundless, Stable Universe" where he built a large, low frequency array. 

The reason he chose Tasmania was to take advantage of the hole in the ozone layer which allowed low frequencies to penetrate the earth’s ionosphere.

Tamworth Regional Astronomy Club has an active radio astronomy group. 

If you are interested in learning more about this fascinating arm of astronomical research, why not come along to one of our Club meetings (details are on our website www.tamworthastronomy.com.au). 

We would be delighted to show you what can be detected and observed with our members’ home-built equipment.

This is the first of a series of articles by Barry Gilbert on radio astronomy. 

TUNED IN: Barry Gilbert demonstrating some of his home-built radio astronomy equipment at TRAC's Stargazing Tamworth event held in July. Photo: Margie Schofield

TUNED IN: Barry Gilbert demonstrating some of his home-built radio astronomy equipment at TRAC's Stargazing Tamworth event held in July. Photo: Margie Schofield

Star map for mid October. Image courtesy of SkySafari, skysafari.com

Star map for mid October. Image courtesy of SkySafari, skysafari.com