SETI researchers believe that the best way to discover other intelligent life in the galaxy is to look for evidence of technology developed by that life. In the belief that intelligent beings on other worlds would eventually develop radio technology, researchers have used large radio telescopes to search the sky. In 1960, the first SETI experiment unsuccessfully examined two stars at a single radio frequency. After several dozen additional searches, the National Aeronautics and Space Administration (NASA) in 1992 began a two-part project known as the High Resolution Microwave Survey. Researchers searched for weak microwave (short radio wave) signals originating near specific stars that are similar to the sun. They also started to scan the entire sky for strong microwave signals. In 1993, the United States Congress, in a budget-cutting measure, instructed NASA to end the project. SETI research continues in the United States under private support.
In 1998, astronomers began to search for pulses of laser light. The astronomers reasoned that intelligent beings on a planet orbiting a distant star might have developed powerful lasers. The beings might have transmitted brief pulses of laser light into space as a signal to observers on other planets. They would have used pulses so that the observers could distinguish the laser light from the bright, steady light coming from their star. Astronomers on the earth would be able to distinguish powerful pulses that were a few billionths of a second in duration.
Contributor:
Michael J. Klein, Ph.D., Radio Astronomer, Jet Propulsion Laboratory, California Institute of Technology; coauthor, Cosmic Quest: Searching for Intelligent Life Among the Stars.
How to cite this article:
To cite this article, World Book recommends the following format:
Klein, Michael J. "Extraterrestrial intelligence." World Book Online Reference Center. 2005. World Book, Inc. http://www.worldbookonline.com/wb/Article?id=ar189230.
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