The official U.S. government position on extraterrestrial life and the three major efforts to search for it. Clockwise from top left: The development and testing of hypotheses on extraterrestrial life is known as "exobiology" or "astrobiology", although astrobiology also considers Earth-based life in its astronomical context. Many scientists consider extraterrestrial life plausible, but there is no direct evidence of its existence. Since the mid-20th century, there has been an ongoing search for signs of extraterrestrial life, from radios used to detect possible extraterrestrial signals, to telescopes used to search for potentially habitable extrasolar planets. It has also played a major role in works of science fiction. Science fiction works, especially Hollywood's involvement, has increased over the years the public's interest in the possibility of extraterrestrial life. §Background §Possible basis §Biochemistry All life on Earth is based upon 26 chemical elements.
Related: The Universe: Cosmology, Astronomy & Astrobiology