As humans began to explore outer space in the latter half of the 20th century, radio waves proved a powerful tool. Scientists could send out radio waves to communicate with satellites, rockets and other spacecraft, and use radio telescopes to take in radio waves emitted by objects throughout the universe. However, sometimes radio telescopes would pick up the artificial radio signals from telecommunications. This interference threatened sensitive astronomy observations, causing inaccurate data and even damaging equipment. While this interference frustrated scientists, it also sparked an idea. During the Cold War, a new field emerged at the intersection of radio astronomy and radio communications. It put forward the idea that astronomers could search for radio communications from possibly existing extraterrestrial civilizations. Astronomy usually dealt with observing the universe's natural phenomena. But this new field made the detection of technologically, or artificially produced...
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