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:
“All men are partially buried in the grave of custom, and of some we see only the crown of the head above ground. Better are the physically dead, for they more lively rot. Even virtue is no longer such if it be stagnant. A man’s life should be constantly as fresh as this river. It should be the same channel, but a new water every instant.”
—Henry David Thoreau (1817–1862)