Backyard Dishes

Ken Tapping, December 19, 2012

In the sky this week…

  • Jupiter rises around 3pm.
  • Mars rises around 10 p.m., and Saturn around 2 a.m.
  • Saturn rises at 4 am and Venus around 6:30 am, with the planet Mercury close by.
  • The Moon will reach First Quarter on the 19th.

The first true radio telescope was built by an amateur. In the 1930’s Grote Reber, an electronics engineer and radio amateur, built a dish about 10m in diameter in his Wheaton, Illinois back yard.  For a while, his discovery of radio emissions from the Milky Way was ignored by the astronomical community. However, then World War II happened. The scientific and engineering worlds were brought together and severely shaken up. The result was new technologies and a broader understanding.

After the war radio astronomy grew almost explosively, with instruments built from equipment left over from the war giving way to custom made radio telescopes. These antennas and the electronics on them were way beyond what amateurs could afford and radio astronomical became the province of professional scientists. 

That does not mean that amateurs had dropped out of existence. Around the world enthusiasts were sifting through what could be found on the surplus market, pulling old televisions apart and adapting amateur radio equipment to build backyard radio telescopes. Amateurs were monitoring storms on the Sun, making crude maps of the Milky Way and detecting the brightest sources of cosmic radio waves: the remains of exploded stars, from distant galaxies, and even the emissions from the cold hydrogen gas clouds that fill space. However, by this time the instruments available to professionals were thousands or more times as sensitive as anything possible in the backyard.

This rapid pace of technical innovation ensured this situation did not survive for long. Domestic satellite TV appeared, first using those three or four-metre dishes in the backyard. When these were superseded by the higher-frequency, smaller dishes common today, the equipment on those older dishes became inexpensively available to experimenters. Soon backyard radio telescopes were picking up quasars, mysterious radio galaxies that existed in the universe’s past.  Amateur and professional astronomy were starting to overlap.

Today another revolution is happening. In Canada, The Netherlands and other countries, some of the older radio telescopes are now going out of use and are being take over by amateurs.  Funding might be slim, but enthusiasm, dedication, creativity are not in short supply. Such people are not likely to be put off by being told “That can’t be done”.

Since this is the last article before the holidays, I wish you a Merry Christmas and Season’s Greetings. Keep your comments and suggestions coming! I just estimated that in 2013 I will write my 1,000th article. Thanks to the continuing and often startling progress we are making in astronomy, I don’t anticipate any shortage of things to write about.

At 11:12, Universal Time (that’s 06:12AM EST and 03:12 PST) on 21 December, the Sun reaches the southernmost point in its annual trail around the Sky. We call this point the Winter Solstice. Around this time our days contain the smallest number of hours of daylight. From there the days start getting longer, slowly at first and then faster and faster.

Ken Tapping is an astronomer with the National Research Council's Dominion Radio Astrophysical Observatory, Penticton, BC, V2A 6J9.

Telephone: 250-497-2300
Fax: 250-497-2355

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