|The woo is out there|
|Aliens did it...|
|... and ran away|
“”The gods watch over us and guide our destinies, many human cultures teach; other entities, more malevolent, are responsible for the existence of evil. Both classes of beings, whether considered natural or supernatural, real or imaginary, serve human needs. Even if they're wholly fanciful, people feel better believing in them. So in an age when traditional religions have been under withering fire from science, is it not natural to wrap up the old gods and demons in scientific raiment and call them aliens?
|—Carl Sagan, The Demon-Haunted World|
"Extraterrestrial" ("ET") describes any object or being beyond the planet Earth; "an extraterrestrial" almost invariably refers to other life forms, also known as EBEs (Extraterrestrial Biological Entities). Because of the sheer scale of the cosmos, the possibility that we are the only form of life in the entire universe is remote; therefore some form of life is likely to exist elsewhere on other planets (although some very exotic ideas have been bounced around the place that don't require planets). Fairly primitive life, such as bacteria, has been hypothesized by scientists such as Carl Sagan to even exist elsewhere in our own solar system, although no reliable evidence for this has been found. More advanced life is likely to have formed outside the solar system and many people — kooks and rational thinkers alike — are convinced that it's out there just waiting to be found.
 Intelligent extraterrestrial life
The narrower and arguably more common definition of "extraterrestrial" is "an intelligent life form that is of extraterrestrial origin" — an alien, in other words. Normally they are thought of as aliens who visit this planet, for whatever reason that aliens might want to visit this planet. This is a pretty cool idea because, assuming communication is even possible with such beings, it would afford the opportunity to compare observations about the nature of reality. This is also cool because, along with spaceships and laser guns, the encounter with aliens is every nerd's dream. As such it is the subject to a lot of crackpot thinking and conspiracy theories. These beliefs range from aliens communicating telepathically with people — similar to mediums talking to the dead — to deliberate coverups by world governments and reverse engineering of alien technology. Despite the prevalence of such beliefs, and the fantastic and attractive narratives that they produce, they are most likely completely and utterly bullshit. No convincing evidence has ever been found in favor of the existence of such beings, let alone the idea that they may be on Earth right now.
Claims that some UFOs are of extraterrestrial origin and claims of alien abduction have not been substantiated and both phenomena can be easily and simply explained without invoking little green men with anal probes. Firsthand accounts of interactions with ETs tend to be anecdotal and often unreliable with little or no physical evidence presented. As a result, investigation of alien encounters by science is difficult. Since ETs seem reluctant to do their abductions near anyone appropriately equipped to document them, we have no hard evidence or reason to believe that they are on Earth interacting with us on a near daily basis.
Or maybe they just don't live nearby? Or maybe they just don't like us enough to talk to us
face to face face to tentacle? Extraterrestrials, it seems, are still confined to the world of science fiction and wildly entertaining conjecture by exobiologists.
 Drake Equation
The Drake Equation is an attempt to quantify the likelihood of alien civilizations being capable of communicating with humans on Earth. Named after radio astronomer Frank Drake, it contains a number of variables such as number of stars in a galaxy, number of planets suitable for life, etc. An interactive version can be found here.
One of the main issues with the Drake Equation is the estimated life span of any advanced civilization, i.e., once it becomes advanced enough to communicate, how long before it blows itself up? While any value for this is necessarily speculative (we're dealing with a sample size of zero, since our only example is our own society, which we can't know how long will last), Drake's original estimate for this value is 10,000 years, while a more modern approach by Michael Shermer set it to only 420 years. This means that any signal received from space (given the enormous distances between stars) could well be from an already long-dead civilization.
Based on the anecdotes and "research" of ufologists and abductees over the last 50 years or so, the aliens that have supposedly come to Earth have been described as "appearing" in many different forms. This indicates that either Earth is improbably interesting to many, many varieties of aliens — or the reports are the result of hyperactive imaginations. Often, "surprisingly" there is a good correlation between the culture that has observed alien life and what it looks like. The "Grey" species is undoubtedly the most commonly imagined and the most commonly depicted in fiction, from Close Encounters of the Third Kind to the Asgard from Stargate. Similarly, the "flying saucer" shape only became prevalent after UFOs were reported as being "saucer-like", which people misinterpreted as being a description of shape, rather than how they moved through the sky. Some early close encounters reported dart-shaped or cigar-shaped rather than saucer-shaped UFOs, before the saucer meme became predominant.
- the Greys: These are the most famous popular aliens. They are short and have really big heads, no hair, grey skin, either very small or no mouth and nose, and really big eyes. They are the most commonly reported aliens in North America. They seem to have an agenda, but the grey agenda should not be confused with the gay agenda (although both seem to involve anal probing).
- the Nordics: These look like a Nazi's wet dream, although taller and not so into Hitler. For some reason, they like to abduct Europeans more than Americans.
- the Reptilians: Also known as the Gorn, they look like sentient dinosaurs. Like the Greys, they too have an agenda, theirs involving the shadow conquest of Earth. David Icke and his followers believe that Queen Elizabeth, the Bush family, and nearly every other major politician is actually a reptilian in disguise. Seems reasonable enough.
- the Designers: Also known as the Elohim (singular Elohah), they look exactly like a small version of a Japanese person because, according to Raelians, they made us in their image. They also gave messages to different populations through religious figures like the Buddha, Jesus, Muhammad, and Moses.
- the Pleiadians: They really care about us and are into multi-dimensional physics.
- Rods: Ufologists disagree as to whether these are aliens or spacecraft; more sensible people agree that they are moths.
- Grand Imperial Warlord Xenu: This is Scientology. 'Nuff said.
Sadly for those who believe in these fantasy people, there is no actual reliable evidence for any of them, as their existence is based solely on people's personal testimony, which is frankly useless. There was a very close call when footage of an autopsy was "leaked" in the 1990s, but this was revealed to be a hoax far too soon for it to be any fun.
 Contact with Earth
Some of the aliens' favorite hobbies while on our planet include:
- Building the Giza pyramids
- Making crop circles
- Abducting Texans for bizarre sexual experiments
- Using their "flying saucers" to buzz unsuspecting drivers, often in, again, Texas
- Taking our jobs and sponging off our welfare systems
- Hollowing out the Earth to build their secret bases
- Eating the dinosaurs
- Mutilating cattle
- Anal Probing
In November 2011, the United States White House officially stated that the US (and as far as they knew, no other country) has never had contact with alien life. Of course, they also said they do not know who shot Kennedy; it's apparent who's lying, isn't it?
 In a nutshell
 See also
- Alien abduction
- Alien invasion
- The Brookings Report
- Fermi paradox
- Intervention theory
- Unidentified flying object
- Real Grey Alien Pictures and Videos – All about the greys
- AlienResistance.Org – Another fine example
- Message from the Designers – This website claims that extraterrestrials somehow designed us and gave us messages via religious leaders