|The woo is out there|
|Aliens did it...|
|... and ran away|
“”If aliens ever visit us, I think the outcome would be much as when Christopher Columbus first landed in America, which didn't turn out very well for the Native Americans
|— Stephen Hawking|
An alien invasion, or an a act of aggression by extraterrestrials against Earth, is a common trope in science fiction. The motivation is typically conquest, as in H.G. Wells' novel War of the Worlds, or biological assimilation, as in the 1956 film Invasion of the Body Snatchers.
Over at Wikipedia, however, the term also includes any non-military encounter between humans and extraterrestrials that occurs on Earth. Fear, rather than the more appropriate responses of curiosity or wonder, dominate the discussion, probably because conventional wisdom about any such encounter has been constructed from narratives of conquest and assimilation. Thus the encounter in Arthur C. Clarke's novel Childhood's End is described as an alien invasion story despite the absence of any military operations or even the presence of many aliens on Earth once they reveal themselves.
Unfortunately, in an effort to appeal to audiences unfamiliar with hard science fiction, alien invasion stories in popular television and film are often trapped in the handful (and shrinking number) of historical metaphors familiar to the general public.
- ↑ 
- ↑ http://www.timesonline.co.uk/tol/news/science/space/article7107207.ece
- ↑ Mike Hale. "Its Might Versus Right Versus Space Monster." The New York Times. June 17, 2011. C16.