Extraterrestrial life, also called alien life (or, if it is a sentient or relatively complex individual, an "extraterrestrial" or "alien"), is life that does not originate from Earth.
These as-yet-hypothetical life forms may range from simple single-celled organisms to beings with civilizations far more advanced than humanity.
Although many scientists expect extraterrestrial life to exist, there is no unambiguous evidence for its existence so far.
The science of extraterrestrial life is known as exobiology.
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