This book records the long scientific search for extraterrestrial intelligence (SETI). Although philosophical speculation about alien civilizations dates to antiquity, the invention of the telescope in the 17th century inspired scientists like Johannes Kepler, Galileo Galilei, René Descartes, and Christiaan Huygens to consider the possibility of intelligent creatures living on the Moon or on the planets of our solar system. By the late 19th century, Mars became the focus of attention for astronomers searching for civilized life near the earth. The belief that Mars contained a superior civilization capable of building a global system of irrigation canals on the planet was supported by the Italian astronomer Giovanni Schiaparelli and the American Percival Lowell. In the 1960s and 1970s, data gathered by Soviet and American spacecraft challenged the assumption that Mars was the habitat for life of any sort. As the hunt for alien civilizations in the solar system waned, a new search began for signs of intelligent life in remote parts of the universe. This search used radio telescopes to scan the skies for any messages transmitted to earth by advanced extraterrestrial civilizations. Distinguished modern astronomers and physicists — Frank Drake, Philip Morrison, Carl Sagan — were convinced that electronic technology would allow contact with civilizations located many light years from earth. Unfortunately, the search for extraterrestrial intelligence was compromised by anthropomorphism (attributing human qualities to alien life and culture) and by an unconscious religious outlook that the superior beings living in outer space would help solve pressing social, economic, and technological problems.