Compare opinions of world leading experts and influencers.

Have aliens from outer space visited Earth?

The belief that aliens have visited Earth is based on countless sightings of UFOs (Unidentified Flying Objects), reports of alien abductions, and other mysterious phenomena such as crop circles. Skeptics believe the evidence for these claims is weak.

Implications to Other Questions

Experts and Influencers

Suggest Expert Quote (click to expand, no login required)
Experts In Scientology

L. Ron Hubbard    Founder of Scientology
Seventy-five million years ago a tyrant named Xenu ruled the Galactic Confederation, an alliance of 76 planets, including Earth, then called Teegeeack. To control overpopulation and solidify his power, Xenu instructed his loyal officers to capture beings of all shapes and sizes from the various planets, freeze them in a compound of alcohol and glycol and fly them by the billions to Earth in planes resembling DC-8s.
01 Jan 1952    Source

Experts In Logging

Travis Walton    Alien Abductee
Their bald heads were disproportionately large for their puny bodies. They had bulging, oversized craniums, a small jaw structure, and an underdeveloped appearance to their features that was almost infantile. Their thin-lipped mouths were narrow; I never saw them open. Lying close to their heads on either side were tiny crinkled lobes of ears. Their miniature rounded noses had small oval nostrils.
05 Nov 1975    Source

Experts In Military

Clifford Stone    Retired U.S. Army Sgt.
I was involved in situations where we actually did recoveries of crashed saucers, for a lack of a better term, and debris thereof. There were bodies that were involved with some of these crashes, also some were alive. While we were doing all this, we were telling the American public there was nothing to it.
10 May 2001    Source

Experts In Aeronautical Engineering

Edgar Mitchell    Retired NASA Astronaut
I happen to have been privileged enough to be in on the fact that we've been visited on this planet and the UFO phenomena is real.
24 Jul 2008    Source

Experts In Science

Robin Hanson    Economics Professor
Mostly Disagree
Since the universe is thirteen billion years old while human civilization is only a few thousand years old, alien civilizations out there would most likely be millions and perhaps billions of years more advanced than us. Given such a lead, it is quite plausible they could make devices able to display all of the phenomena reported for UFOs. There is nothing in physics that suggests UFOs are not aliens. No, the main argument against UFOs as aliens is that this is an implausible social scenario.
20 Aug 2008    Source

Sub-Arguments Of This Expert:
Is intelligent extraterrestrial life common in our galaxy?
   Mostly Disagree

Richard Feynman    Nobel Laureate in Physics
Mostly Disagree
I think that it is much more likely that the reports of flying saucers are the results of the known irrational characteristics of terrestrial intelligence than of the unknown rational efforts of extra-terrestrial intelligence.
01 Jan 1960    Source

Eliezer Yudkowsky    Artificial Intelligence Researcher
I don't believe that UFOs are alien visitors, but my skepticism has nothing to do with all the crazy people who believe in UFOs - the existence of wacky cults is not much less expected in the case that aliens do exist, than in the case that they do not. ... I don't believe aliens would (a) travel across interstellar distances AND (b) hide all signs of their presence AND THEN (c) fly gigantic non-nanotechnological aircraft over our military bases with their exterior lights on.
14 Mar 2010    Source

Seth Shostak    Senior Astronomer at the SETI Institute
It's hardly likely to amaze you, but I'm skeptical. I don't think the evidence laid on the table as proof of extraterrestrial visitation is compelling, and I certainly don't buy the argument that better evidence (in fact, all the really good evidence) has somehow been collected by the governments of the world and stacked up in secret storage lockers.
18 Apr 2011    Source

Experts In Philosophy

Robert Todd Carroll    Philosophy Professor
The main reasons for believing in UFOs are the questionable interpretations of visual experiences, the testimony of many people, the inability to distinguish science fiction from science, the willingness to trust incompetent men telling fantastic stories, the ability to distrust all contrary sources as being part of an evil conspiracy to withhold the truth, and a desire for contact with the world above. Belief in aliens and UFOs is akin to belief in supernatural beings.
04 Apr 2009    Source

Suggested Expert Quotes

H. P. Lovecraft
There had been aeons when other Things ruled on the earth, and They had had great cities. Remains of Them, he said the deathless Chinamen had told him, were still be found as Cyclopean stones on islands in the Pacific. They all died vast epochs of time before men came, but there were arts which could revive Them when the stars had come round again to the right positions in the cycle of eternity. They had, indeed, come themselves from the stars, and brought Their images with Them. "Call of Cthulhu" narrator


Add Your TakeOnIt (click to expand, no login required)
0 Points      MTC      23 Feb 2013      Stance on Question: Disagree
Extraterrestrials almost certainly exist (you would have to be incredibly arrogant to believe this is the only planet in the universe where life exists), but have almost certainly not visited Earth.

0 Points      Anonymous      04 Dec 2010      Stance on Question: Neutral
I believe there is so much more to know than is known. Usually, the subject of ufo's is met with laughter or ridicule; open minds are few and far bet twee n.

0 Points      Benja      04 Dec 2010      General Comment
"I believe there is so much more to know than is known."
One's lack of knowledge is not evidence for the way the world is.

"open minds are few and far between"
See Are people who reject theories as unscientific closed minded?.

0 Points      Clive      28 Jul 2009      Stance on Question: Disagree
I really don't think aliens have come to earth. Maybe there is a small possibility that bacteria or single celled organisms may have possibly hitched a ride on the back of an asteroid. But I couldn't image that would be very likely.

0 Points      wayne helton      05 Oct 2014      Stance on Question: Disagree
why do people have such a hard time believing that we come from space. where is earth? duh in space..anything on earth came from space....period

0 Points      wayne      05 Oct 2014      Stance on Question: Agree
sorry wrong stance on my first statement