Radio Telescopes (1)

Radio telescope is an instrument for studying the radiation at radio wavelengths emitted by celestial objects. Visible light is not the only way by which stars give off energy. Stars give off many other kinds of radiation as well, such as gamma rays, X-rays, ultraviolet rays, infrared rays and radio waves. Like visible light, these are all electromagnetic waves. They differ only in their wavelength. The atmosphere blocks most of these radiations. Only radio waves, light and infrared can get through.
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The American scientist Karl Jansky (1905-1950) first detects radio waves, in 1931 using homemade equipment (above), investigated the static affecting short-wavelength radio-telephone communication. He deduced that this static must come from the centre of the galaxy.
 



AMATEUR ASTRONOMER

On hearing about Jansky's discoveries, American amateur astronomer Grote Reber (1911-) built a large, moveable radio receiver in his backyard in 1936. It had a parabolic surface to collect the radio waves. With the 9-m (29-ft) dish (above), he began to map the radio emissions coming from the Milky Way. For years Reber was the only radio astronomer in the world.

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