Extraterrestrial life (from the Latin words: extra and terrestris ) is defined as life that does not originate from Earth. It is often also referred to as alien life, or simply aliens (or space aliens, to differentiate from other definitions of alien or aliens). These hypothetical forms of life range from simple bacteria-like organisms to beings far more complex than humans.
The development and testing of hypotheses on extraterrestrial life is known as exobiology or astrobiology; the term astrobiology, however, includes the study of life on Earth viewed in its astronomical context. Many scientists consider extraterrestrial life to be plausible, but there is no conclusive evidence for 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.
Read more about Extraterrestrial Life: Background, Possible Basis, Planetary Habitability in The Solar System, Scientific Search, The Drake Equation
Famous quotes containing the word life:
“He was discontented and wasted his life into the bargain; and yet he rated it as a gain in coming to America, that here you could get tea, and coffee, and meat every day. But the only true America is that country where you are at liberty to pursue such a mode of life as may enable you to do without these, and where the state does not endeavor to compel you to sustain slavery and war and other superfluous expenses which directly or indirectly result from the use of such things.”
—Henry David Thoreau (1817–1862)