Peter Howarth – “Radio astronomy for the slightly nervous”

Wednesday 7 April 2010

We were pleased to welcome back Peter Howarth from our neighbour the Cambridge Astronomical Society.  Peter is a radio ham as well as amateur astronomer, so it seemed fitting that he combined the two subjects in his talk. It also seemed appropriate as so much pioneering radio astronomy has been undertaken in the Cambridge area.

Peter explained the background to radio transmission and the position of radio frequencies in the electromagnetic spectrum. These frequencies vary according to the wavelengths used particular transmissions. Long wave radio, for example, uses wavelengths measured in meters, but the one of interest to astronomers is the shorter wavelength radio detected from outer space. This was first detected as a background hiss by Karl Jansky in 1933. Further radio astronomy was carried out by Grote Reber and others, particularly driven by the Second World War and its aftermath, when there was a large amount of surplus equipment available for research. Martin Ryle, Tony Hewish and colleagues used some of this surplus radar to build radio telescopes at Lords Bridge near Cambridge leading to pioneering work on extragalactic radio astronomy. In 1961, Penzias and Wilson used a radio telescope to observe the microwave background left over from the Big Bang.

What about amateur radio astronomy? Peter suggested a few examples of what amateurs could build using simple electronic circuitry to listen in on solar flares or even the radio noise of Jupiter. The simplest suggestion was to place a two meter wire in the sound card of a computer and listen to radio noise created by lighting bouncing of the ionosphere. There will be some interference from the 50Hz mains supply, but this project seems well worth a try. Maybe we’ll use it on one of the Papworth observing evenings to complement the optical astronomy?

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