Detecting Invisible Signals with Radio Telescopes

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The Radio Wave Effect

Radio telescopes are actually the counterpart of optical telescopes when it comes to gathering information from the cosmos but they use radio waves instead of optical wavelengths. It is actually a parabolic antenna that can be directed to track desired targets in the sky. These facilities can also be used to receive and transmit signals from satellites and space probes. Radio telescopes operate on in portions of electromagneticspectrum with wavelength on the order of miles/kilometers, unlike in optical telescopes which rely on light waves, which are on the order of hundreds of nano-meters (billionths of a meter).

Radio telescopes use a large parabolic dish with a receiver located at the vertex of the dish. The surface area of the dish serves as the reflector to bounce the signal towards the center for efficient reception of radio signals. Usually, radio telescopes are arranged in an array for maximum efficiency. Also, they are built in areas very far from cities and urbanized locations to minimize interference they may be receive from modern devices like radios, TVs and radars. This is the same principle used when it comes to optical telescopes when they are built in high and uncluttered places to avoid light interference from other human activities but it also gives them a much clearer view of the night sky being above the denser part of the atmosphere.

The very first radio telescope was built in 1931 by Karl Jansky. He was assigned to investigate electromagnetic emissions which might affect the radio telephone services used by Bell Laboratories. The device was used to receive frequencies in wavelengths around 14 meters, at about 20 Mhz.

Some Notable Radio Telescopes:

RATAN-600 - Built by the USSR

Green Bank Telescope - Germany, operating since 2000

The Big Ear - United States-1998, Ohio State University

Arecibo Radio Telescope - Puerto Rico

Radio telescopes have been very useful in detecting activities in space in the absence of light signals. Because of the wider scattering capacity of radio waves, we can easily capture more signals and interpret astronomical observations. Who knows, we might even be able to contact an extraterrestrial civilization in deep space!