Radio Astronomy

By Sean McKenna, T.A.S.

Karl Jansky

Radio astronomy was "born" in 1931 when Karl Jansky discovered radio noise from outside the Solar System. The full significance of this discovery was not realised until after the Second World War.
Then scientists using new techniques and better equipment began to realise that significant information on the universe could be obtained from a different part of the electromagnetic spectrum than that available from using conventional optical telescopes.

Initially the resolving power of radio telescopes was not very great, for instance, the 250ft Mark 1. Dish at JODRELL BANK, working at a wavelength of one meter has a resolving power of a little under one degree of arc. This is about twenty times inferior to the few minutes of arc resolving power of the human eye. This limitation is nowadays overcome by linking several large radio telescopes into a single RADIO INTERFEROMETER. If two telescopes are used then the resolving power is equivalent to a single telescope with an aperture equal to the distance between the aerials.
Modern Radio Interferometer arrays include, the VERY LARGE ARRAY in New Mexico and the MERLIN array at Jodrell Bank. These systems can produce radio maps with a resolution of a few hundredths of seconds of arc. So within the space of a single generation radio telescopes are now able to give us resolutions of from ten to a hundred times superior to that obtained from the large optical telescopes.

Radio astronomy has revealed objects and features of the universe unknown through optical observations and also helped us to better understand well known objects, such as the Sun and nearby stars. Discoveries include, PULSARS, QUASARS and the COSMIC BACKGROUND RADIATION. With almost daily advances being made in design and technique who knows what future discoveries will reveal about the nature of the universe ?

However this is all very High-Tech and the technical resources behind all this can seem well beyond the capabilities of the average amateur astronomer. This need not be the case, as I hope to be able to show, shortly.

Coming soon ......

BUILDING A SIMPLE RADIO TELESCOPE


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