An unidentified flying object (UFO) is, at its simplest, an airborne object that an observer cannot identify - a definition that carries no inherent implication of extraterrestrial visitation, since it could equally describe a weather balloon or something misinterpreted, according to psychiatrist Benjamin Simon, who treated Betty and Barney Hill after their sighting.1 The term “flying saucer” entered popular use the day after Kenneth Arnold’s 1947 sighting, when newspapers first coined it.2 That December, the United States Air Force (USAF) Chief of Staff established Project Sign to investigate the first recorded UFO observations,3 and in 1952 the Air Force Director of Intelligence launched its successor, Project Blue Book.4 Between 1947 and Blue Book’s closure in 1969, the Air Force investigated more than 12,000 claimed sightings.5
Blue Book’s end was described by consultant J. Allen Hynek as the “coup de grace” to the UFO era - in his account, science had spoken, and the thousands of people who had reported sightings could be dismissed as deluded, hoaxers, or mentally unbalanced.6 A 1985 Air Force summary of the programme’s conclusions told the public that nothing had happened to warrant resuming the investigation,7 and from 1969 the official position of the United States military was that UFOs posed no threat to national security and did not merit further study.8 Journalist David Marler has said that for decades the USAF, the FBI and the Central Intelligence Agency (CIA) maintained a policy of denying, dispelling and debunking the subject.9 A declassified CIA assessment of reconnaissance aircraft found that more than half of the UFO reports investigated during the 1950s and 1960s were in fact American reconnaissance flights.10
That posture shifted with disclosure of the Advanced Aerospace Threat Identification Program (AATIP). For years the programme investigated UFO reports, according to Department of Defense officials, participant interviews and records obtained by The New York Times.11 Luis Elizondo is the former head of AATIP, the Pentagon unit that researched UFOs, now known as Unidentified Anomalous Phenomena (UAP).12 The programme was tasked with investigating both UFOs and UAP,13 and it compiled video and audio recordings of reported incidents, including footage from a Navy F/A-18 Super Hornet showing an aircraft surrounded by a glowing aura, travelling at high speed and rotating as it moved.14 Elizondo has said that Jay Stratton proposed calling the objects “Unidentified Aerial Phenomena” rather than “Unidentified Flying Objects” to make the conversation easier with leadership,15 since Pentagon leadership did not want to be associated with the label’s historical stigma, in Elizondo’s account.16 That culture of denial changed with the leaking of infrared footage captured aboard US fighter jets and Navy ships, released by the Department of Defense in 2017.17 David Fravor has said the resulting 2017 New York Times report removed the stigma from the topic.18
Individual witness accounts span decades. Betty Hill and Barney Hill’s case began with a six-page report to the National Investigations Committee on Aerial Phenomena describing their sighting.19 Betty Hill’s account, relayed by Benjamin Simon, described the object landing, emitting beeping sounds, stalling their car’s motor and leaving silver-like spots on the vehicle,20 and Betty held far more conviction that what they had seen was a UFO than Barney did.21 In a later, well-documented case, the crew of a Tajik Air Boeing 747SP first saw an intensely bright light approaching from the eastern horizon at great speed and at a higher altitude than their own aircraft, during the 1994 Tajik Air Boeing 747SP sighting over Kazakhstan.22 The crew watched it manoeuvre in circles, corkscrews and 90-degree turns under very high g-forces for approximately forty minutes,23 before it adopted a horizontal high-speed course and disappeared over the horizon;24 because the sighting occurred in darkness, the crew could not discern its shape.25 Pilot Ed Rhodes has said that, on the basis of its speed and manoeuvrability, he considers the object to have been extraterrestrial and under intelligent control.26 Sightings of this kind persist: Chris Ramsay’s DEBRIEFED programme recounted a witness, Eric, who in spring 2013 saw a cigar-shaped object while flying from Denver to Saskatchewan at cruising altitude,27 pointed at both ends, solid white and showing no visible means of propulsion,28 travelling in the opposite direction to his aircraft at the same altitude before passing out of view,29 at an estimated 1,100 to 1,300 kilometres per hour.30
Researchers have proposed differing frameworks for the phenomenon. Religious studies scholar Diana Walsh Pasulka has said that Jacques Vallée’s approach addresses three aspects of the subject: the physical, the testimonial evidence of experiencers, and the social question of how belief in the phenomenon persists regardless of verifiable evidence.31 Vallée himself has argued that official statements downplaying radar and satellite detection are misleading, since radar operators classify such objects as “uncorrelated targets” rather than reporting them as UFOs.32 Jason Samosa has said Vallée’s approach examines the cultural impact of UFOs over time on human belief systems and infers from that impact the motivations of whatever is said to operate the phenomenon,33 and has separately argued that the extraterrestrial hypothesis is inadequate to the data, since craft have reportedly landed repeatedly and appear in many different forms.34 Samosa has also said that, in Messengers of Deception, Vallée warned a worldwide mass appearance of UFOs could cause cults to blossom while trust in government collapsed.35 Whitley Strieber has said UFOs are routinely observed displaying both small size - sometimes only a few metres in diameter - and seemingly limitless propulsion,36 and considers zero-point energy the one known force that might explain it.37 Michael Hesemann, considered one of Europe’s leading experts on the UFO phenomenon,38 has pointed out similarities between Marian visions and UFO sightings,39 though he has said he tries to avoid interpretation, preferring to relate the history of such events in their own light despite not denying the parallels.40 Physicist James MacDonald took a more cautious, evidentiary approach: as a scientist, he said he was not entirely comfortable relying on hearsay in UFO cases,41 and considered that a soundless object hovering stationary, in conditions that did not indicate ball lightning, also ruled out meteors as an explanation.42
Investigative reporting has probed the scale of official interest. George Knapp has said the Advanced Aerospace Weapon System Applications Program (AAWSAP) - AATIP’s associated research effort - was likely the largest UFO study ever conducted with government funds,43 and its data set has been described as the largest and most sophisticated UFO warehouse ever created, cataloguing more than 200,000 cases.44 Journalist Leslie Kean has said extraordinary UFO sightings have occurred in America for more than sixty years, many observed by pilots and military personnel and many yielding physical evidence,45 and that volumes of case studies have been published by qualified researchers since the 1950s46 - work that forms part of the broader field of ufology. Podcaster Jesse Mitchells has said the United States government has been conducting covert reverse-engineering programmes on UFOs for approximately 70 to 80 years.47 Major Murphy has suggested that confusion surrounding the UFO mystery may have been deliberately introduced to keep scientists away and create conditions for a new form of social control.48 Musician Tom DeLonge remains engaged with the subject and, according to journalist Ross Coulthart, has never let it go,49 despite otherwise being quiet on the topic in recent years.50 Coulthart has said letters he wrote to people he believed might know something about a project called The Legacy Program produced the responses that most significantly changed his own view of UFOs.51 Strieber has recounted that Jimmy Carter, while president, apparently asked the Department of Defense to tell the public the story about UFOs,52 and attributes Carter’s subsequent refusal to discuss the topic to having been told that presidential disclosure would be a “trip wire”.53 A 2023 congressional hearing on UAP heard that more than 20 percent of Americans have reported seeing UFOs or UAP,54 and Representative Tim Burchett has said some members of Congress have confided in him that they had sightings of their own while wishing to remain anonymous.55