Radio Telescopes: listening to the heavens
Listening to the silence...
Listen
to a sample of what astronomers hear when they tune into the universe.
The use of radio telescopes to search for intelligent life has been widely publicized by big movies such as "Contact." Although most radio telescopes are used specifically to gather data about the physical universe, a few are trained toward space with the ultimate goal of receiving radio signals from other civilizations. Project Phoenix is one such endeavor. The radio telescope used, which is the largest in the Southern Hemisphere, is aimed at nearby "sun-like" stars in the hope they will have planets capable of supporting life.
Most of this "listening" is done by computer. The search is for narrow-band radio signals that would indicate a purposeful transmission.
In addition to radio telescopes, a new trend has astronomers looking into the heavens at visible frequencies on the electromagnetic spectrum. The hope is that other life forms may use laser signals to attempt contact.
"I know the stars by heart...our great blazing kings of the sky, I know them, and when they rise and when they fall, and now I watch for the light, the signal fire"
--Aeschylus
A radio telescope "sees" only a fraction of the sky at one time, amounting to a circle of only a few arcminutes. This means that astronomers have to decide whether to do a scan of the whole sky, spending only seconds (or less) in each location, or focusing on a choice location for longer periods of time. Radio telescopes are also limited to searching in only a narrow band of frequencies, or channels. Simultaneous channel monitoring, even up to a million channels at once, still would yield only a small portion of possible transmission frequencies.
A hope of
astrobiologists is to have instrumentation capable of detecting not only
extrasolar planets, but the composition of their atmospheres.
Atmosphere is a huge indicator of biotic activity.
Voyager was sent into space with a "message" for any life that may find it: a gold plated copper disk, with a stylus for playing the recorded sounds. For more information on this greeting, click here.
Read more on the possibility of contact:
Finding great quantities of oxygen, and oxygen in combination with methane, may be a sign that something is replenishing the atmospheric supply of both gases. Oxygen is highly reactive, and methane will react with any oxygen present. Certain chemicals, including industrial pollutants, may be a sign of an intelligent species.
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