Encyclopedia Britannica Article on UFOs
by Dr. Thornton Page

The New Encyclopedia Britannica, 15th Edition, 1974-1984, Macropedia, Volume 18, pages 853-857


Unidentified Flying Objects

Although sightings of unusual phenomena in the sky have been reported since ancient times, an extraordinary outburst of such sightings in the late 1940s and over the next two decades created a sharp scientific controversy, centered in the U.S., but extending around the globe. The term UFO, short for "unidentified flying object," was introduced in 1953 by the U.S. Air Force. An earlier term, "flying saucer," is still widely used in Australia, South America, and Europe, while in the Soviet Union the Russian equivalent of "flying sickle" is used. The term UFO is not restricted to saucer-shaped objects nor even to objects in the sky, and in general refers simply to any sighting the observer could not understand, even though it may have been later identified.


A series of radar detections coincident with visual sightings near the National Airport in Washington, D.C., in July, 1952, led the U.S. government to establish a panel of scientists headed by H.P. Robertson, a physicist of the California Institute of Technology, and including engineers, meteorologists, physicists, and an astronomer. The thrust of public and governmental concern was indicated by the fact that the panel was organized by the Central Intelligence Agency (CIA) and was briefed on U.S. military activities and intelligence, and that its report was originally classified Secret. Later declassified, the report revealed that 90 percent of UFO sightings could be readily identified with astronomical and meteorological phenomena (bright planets, meteors, auroras, ion clouds) or with aircraft, birds, balloons, searchlights, hot gases, and other terrestrial phenomena, sometimes complicated by unusual meteorological conditions.

The publicity given to early sightings in the press doubtless helped stimulate further sightings not only in the U.S. but in western Europe, the Soviet Union, Australia, and elsewhere. A second panel organized in February 1966 reached conclusions similar to those of its predecessor. This left a number of sightings admittedly unexplained, and in the mid-1960s a few scientists and engineers, notably James E. McDonald, a University of Arizona meteorologist, and J. Allen Hynek, a Northwestern university astronomer, concluded that a small percentage of the most reliable UFO reports gave definite indications of the presence of extraterrestrial visitors.

This sensational hypothesis, already promoted in newspaper and magazine articles, met with prompt resistance from other scientists. The continuing controversy led in 1968 to the sponsorship by the U.S. Air Force of a study at the University of Colorado under the direction of E.U. Condon, a renowned physicist. The Condon Report, "A Scientific Study of UFO's," was reviewed by a special committee of the National Academy of Sciences and released in early 1969. A total of 37 scientists wrote chapters or parts of chapters for the report, which covered investigations of 59 UFO sightings in detail, analyzed public-opinion polls, and reviewed the capabilities of radar and photography. Condon's own "Conclusions and Recommendations" firmly rejected "ETH" - the extraterrestrial hypothesis - and declared that no further investigation was needed.

This left a wide variety of opinions on UFOs. A large fraction of the U.S. public, and a few scientists and engineers, continued to support ETH. A middle group of scientists felt that the possibility of extraterrestrial visitation, however slight, justified continued investigation, and still another group favored continuing investigation on the grounds that UFO reports are useful in sociopsychological studies. These varying views and attitudes were expressed at a symposium held by the American Association for the Advancement of Science, in December 1969.


Official Records.

In 1948 the U.S. Air Force began to maintain a file of UFO reports called Project Blue Book. By 1969 the project had recorded reports of 12,618 sightings or events, each of which was ultimately classified as "identified" with a known astronomical, atmospheric, or artificial phenomenon, or as "unidentified," including cases in which information was insufficient. In 1969, following the Condon report, Project Blue Book was discontinued. The only other official and fairly complete records of UFO sightings were maintained in Canada, where they were transferred in 1968 from the Canadian Department of National Defense to the Canadaian National Research Council and placed under the supervision of Peter Millman, a meteorologist. The Canadian records totaled about 750 in 1969. Less complete records were maintained in Britain, Sweden, Denmark, Australia and Greece, and were usually destroyed after five years.

Press Reports.

Press reports have been worldwide, including a number from the Soviet Union. But though such reports reflect a general public concern, they tend to emphasize the sensational and are not properly evaluated. No comprehensive summary of press reports has yet been made, but they seem to have followed an eastward moving geographic trend starting with the first widely publicized "flying saucer" sighting in the western U.S. in 1947. Many press reports of sightings on the U.S. East Coast in the early 1950s were followed by reports from Britain, France, the Soviet Union, Australia, and on to the U.S. West Coast in the 1960s. In the 1960s there were many sightings of UFOs "taking off from the ground," a shift from saucer shapes to cigar shapes in the images reported, and a number of reports of effects on the electrical systems of automobiles. Many authorities believe that mass-media coverage of UFOs both stimulated more reports of sightings and encouraged a change to more dramatic events and differently shaped images. A series of feature articles in an Argentine newspaper in 1968 was promptly followed by a number of sightings in Buenos Aires and other cities.

Types of UFO reports.

UFO reports varied widely in reliability, as judged by the number of witnesses, whether the witnesses were independent of each other, by the observing conditions (fog, haze, illumination, etc.), and by the direction of sighting. Typically, the witness who reported a sighting considered the object extraterrestrial in origin, or possibly a military vehicle, but certainly under intelligent control, a conclusion usually based on apparent formation-flying of multiple objects, unnatural motions seemingly centered on a target, or arbitrary alterations in direction, brightness, and motion.

That the unaided human eye plays tricks bordering on hallucinations is well known. A bright light, such as the planet Venus, often appears to move, although a clamped telescope or a sighting bar shows it to be fixed. Visual impressions of distance are also highly unreliable, being based on assumed size. Reflections from windows and eyeglasses can provide superimposed views. Optical defects can turn point sources of light into apparently saucer-shaped objects. Such optical illusions, and the psychological desire to interpret visual images, are known to account for many visual UFO reports. Radar sightings, while more reliable in certain respects, fail to discriminate between physical objects and meteor trails, tracks of ionized gas, rain, or thermal discontinuities. Even "contact events" - in which activities besides sighting were reported - have been found most frequently to involve dreams or hallucinations; the reliability of such reports depended heavily on whether there were two or more independent witnesses.

Sightings and reports may be conveniently classified in four broad categories, for each of which selected examples are given below:

    1. Visual sightings in daytime (some photographed);
    2. Visual sightings at night (a few photographed);
    3. Radar sightings;
    4. Close encounters or physical evidence;

The absence of a given explanation does not necessarily mean that the example constitutes evidence favoring the ETH. It merely means that no explanation is known.

Examples of daytime sightings.

Many of these sightings have been identified with the planet Venus, from its known position in the sky.

Louisville, Kentucky, Jan. 7, 1948. At 1:15 pm the State Highway Patrol reported a flying saucer to the Godman Air Force Base, where the base commander and several other persons saw the object. A group of four USAF F-51 aircraft arrived at the base and three were directed by the control tower toward the UFO. One pilot saw it and started a rapid climb toward it; the other two fighter pilots remained behind and lost radio contact with the first just after he reported that he would climb to 20,000 feet altitude. He had no oxygen equipment and was killed when his plane crashed without further communication half an hour later. The first USAF investigation concluded that the pilot saw Venus, which was in the direction of his sighting, but later discussion suggests that it was a 100-foot "Skyhook" balloon being tested by the U.S. Navy. (This uncertainty is typical of early UFO identifications, and led to greater USAF effort in Blue Book. )

Newton, Illinois, Oct. 10, 1966, 5:20 pm CST. A woman and five children witnessed the slow passage of a metallic object past their farm home. Observing conditions were excellent, with clear, dry weather. The object was first seen by the children, ages four through nine years. The mother responded to the children's call and joined them in the yard, walking parallel with the object's motion. The object moved slowly and uniformly in a westerly direction, at walking speed, approximately 50 feet above the ground. Abruptly turning its nose up and moving rapidly upward, it disappeared from sight in one or two seconds. An analysis of the reported sighting suggested a cigar-shaped spheroid approximately 20 feet long and eight feet in diameter, possibly of aluminum, with longitudinal seams, a small dorsal fin at the rear, and a rectangular, black aperture near the front. A brownish gold design was observed on the lower rear portion. The object was surrounded by a bluish haze that contained luminous bubbles or sparks. No sound was heard except for an unusual vibrating noise perceived for a few seconds when the object was nearest. Seventy minutes later, under dark-sky conditions, an elliptical blue light of the same colour and shape was seen moving in the same general direction by a witness seven miles from the first sighting.

Trementon, Utah, July 2, 1952. At 11:10 AM, a Navy Chief Warrant Officer with his wife and two children was driving along State Highway 30 when they saw a group of strange white objects above the eastern horizon. The officer stopped the car, estimated that there were 12 to 14 of the objects, and photographed them for several minutes, using a 16-mm movie camera. He was sure that the UFOs were large objects at high altitude. Analysis of the film showed that they might have been sea gulls at 2,000 feet distance; at 50,000 feet they would have been moving at 300 miles per hour, executing maneouvers impossible for aircraft known in 1952.

Socorro, New Mexico, April 24, 1964. A patrolman reported that at 6 pm he sighted a "blue flame" about 2,000 feet off Highway 7A. He drove along a ranch road to within 200 feet of a 20-foot hemispherical object standing on four legs near an abandoned shack where he earlier thought he had seen two people dressed in white. As he approached, the UFO took off with a loud roar, apparently emitting a blue jet flame, and climbed in a southwesterly direction away from the highway. There were no other witnesses, although the observer had radioed another patrolman for assistance when he left the highway. After recovering from his fright, the observer located four deep impressions in the soft ground where he said the UFO stood. There were two smaller impressions where a ladder had led to a door seen by the observer.

Examples of Nighttime Sightings.

Many of these sightings have been identified with planets, bright stars, meteors, and airplanes. Some may be explained by the refraction of light in layers of warm air hundreds of feet above the observer, allowing him to see surface lights high in the sky.

Montgomery, Alabama, July 24, 1948, 2:45 am. A pilot and copilot in the cockpit of an airline passenger plane at 5,000 feet altitude, en route from Houston to Boston, saw a dull-red object approaching on a collision course. During the next ten seconds it veered slightly to the right, passed the plane on the right at high speed, then seemed to pull up, and disappeared in the clouds overhead. One passenger on the right side of the plane glimpsed the bright light as it flashed by. There was no disturbance of the plane. The pilots described the object as cigar-shaped, about 1 00 feet long, with two rows of lighted windows, a dark blue glow underneath, and a red-orange jet flame about 50 feet long behind it. They estimated the closest approach to be less than a mile. Authorities concluded that the object was probably a distant meteor.

Dexter, Michigan, March 21-22, 1966. A farmer and several of his friends reported coloured lights that landed in a swamp, where they later saw a "pyramid-shaped object" with lights rippling eerily across its surface in the dark. The next night, several girls at a nearby college reported three large coloured lights moving up and down in a "synchronized" way, and two other co-eds reported a glowing disc in the swamp.

The lights have been interpreted as glowing marsh gas, or will-o'-the-wisp. The faint, fingerlike, glowing methane is often seen low on the ground on damp nights, and is well known to result from decaying vegetation, but its appearance did not fit the large coloured balls seen "landing" in the swamp. This case was lampooned extensively by the U.S. press.

Examples of radar sightings.

Radar measures the distance to a UFO and the direction, which may be affected by refraction of the radio beam in the atmosphere. Several effects can give false radar echoes: electronic interference, reflections from ionized layers or clouds, and reflections from regions of higher temperature or humidity, as in a cumulus cloud. A simultaneous radar detection and visual sighting in the same direction is the most reliable - but not certain - evidence of a physical object.

Lakenheath, England, Aug 13, 1956, 11:00 pm - 3:30 am. Two RAF ground radar stations detected several objects moving at high speed on a clear moonlit night. One was tracked by the first radar as going at about 3,000 miles per hour westward at 4,000 feet altitude; simultaneously, tower operators reported a bright light passing overhead toward the west, and the pilot of an aircraft at 4,000 feet over the airfield saw the bright light streak westward underneath him. The second radar station, alerted by the first, detected a stationary target at about 20,000 feet altitude that suddenly went north at 600 miles per hour. It made several sudden stops and turns. After 30 minutes another fighter was called in and made airborne radar contacts with the object over Bedford (just north of Cambridge, England). Suddenly the object moved around behind the fighter plane, both being tracked by ground radar. The fighter pilot could not "shake" the object. A second plane was called in but never made contact, and all radar contacts were then lost. Several other radar targets were tracked in the same area and several other small moving lights were seen, but all disappeared at 3:30 am.

This is believed to be one of the best established and most puzzling of the unexplained cases.

Colorado Springs, Colorado, May 13, 1967, 3:40 pm. The weather was overcast with scattered rain and sleet showers and gusty winds. As an airliner came in for a landing, the ground radar detected an object beyond it at about twice the range. As the plane landed, the object pulled to the east and passed low over the airport (at 200 feet altitude, about 1.5 miles from the control tower). The tower operators, alerted by the radar operation, saw and heard nothing. The pilot of another aircraft, three miles behind the first, saw nothing when asked to look.

Examples of close encounters or physical evidence.

These include foot impressions described above in Socorro, New Mexico, circular burned patches in fields, and melted patches in road pavement, possibly due to jet take-off. It is barely possible that strong magnetic fields or plasma clouds of ions produced by a UFO could affect the electrical components of an automobile.

Methuen, Massachusetts, Jan. 20, 1967, after dark. Three people were driving northeast on a street bordered by woods, fields, and a few houses. They reported that on reaching the top of a hill they suddenly came upon a straight string of bright red lights moving along the roadside at an altitude of 500-600 feet. When they were almost broadside to the lights, which then were hovering, the object to which they were apparently attached swung around to reveal four distinct lights in a perfect trapezoid. Two red lights formed the top and two white lights formed the base. The red lights resembled a hot electric-stove burner. A reflecting metal was seen about the lights. The centre of the trapezoid was dark. When the driver pulled over to the side of the road directly broad side to the object, his car engine, lights, and radio failed completely. The driver tried to start the car again, but was unsuccessful. No noise was heard as the object began moving slowly and then shot away at great speed in a southwest direction. The driver was then able to start the car, and the lights and radio worked perfectly.

Ubatuba, Sao Paulo, Brazil, Sept. 10, 1957, 12 noon. Three fishermen saw a flying saucer diving into the sea at high speed. Just before reaching the water, it turned sharply upward and exploded into "thousands of fiery fragments." The fishermen picked up several of these fragments, which fell on the beach, and sent them in an anonymous letter to a Rio de Janeiro newspaper. A Brazilian government laboratory did a chemical analysis and announced that the metal was "magnesium of higher purity than attainable in purification techniques known to man." The impurities detected were zinc, strontium, and other trace metals totaling about 0.15 percent. Analysis, however, soon showed that industrial magnesium in the U.S. is a good deal purer (less than 0.002 percent impurities). The abundance of strontium was unusual, however, and may lend some weight to the claim that the Ubatuba fragments were from an extraterrestrial space vehicle.

Southern New Hampshire, Sept. 19, 1961, 11 pm to 2 am. A couple returning to Boston via Lancaster and Concord saw a large disk-shaped object and felt obliged to stop and walk over to it. Their stories, recorded separately under hypnosis by a psychiatrist in Boston in 1964, were consistent and told of their being taken aboard the flying saucer, undressed, and examined by a group of humanoids. Later, psychologists concluded that this widely publicized case was a hallucination by the woman, transmitted to her husband so thoroughly that he "remembered" it as real, even under hypnosis.


In accordance with the conclusions and recommendations from the 1969 Condon Report, the U.S. Air Force terminated its Project Blue Book study of UFOs in December 1969. Several groups of American scientists claim, nevertheless, that the UFO phenomenon warrants further study; and groups in other countries are continuing their studies of UFOs. These studies are of three types:

1. Detailed analysis of reported cases similar to the examples cited above, often called "soft data" because they depend on the reliability of witnesses. The goal is to identify new physical phenomena or to confirm the extraterrestrial hypothesis.
2. Systematic collection of "hard data" by networks of cameras, or radar sets or other instruments that cover a broad area nearly 100 percent of the time without the questionable reliability of eyewitnesses. The goal is often associated with studies of meteors, auroras, or other atmospheric phenomena.
3. Statistical studies of past reports to establish definite psychological and sociological patterns. The duration of the UFO phenomenon over 20 years-puzzles psychologists because mass hysteria has never been so long enduring or so widespread.

It is claimed by many experts that type 1 detailed analyses of soft data, will not produce new information, although some scientists hold that an exceptionally good sighting may occur and lead to significant conclusions

Instrumental developments.

There are at least two instrumental developments that can provide hard data for type 2 studies: "all-sky" camera networks and TV cameras in artificial satellites. The first of these is typified by the Prairie Meteorite Network of 64 automated cameras in groups of four at 16 stations spaced about 140 miles (225 kilometres) apart to cover about 500,000 square miles (1,500,000 square kilometres) of the U.S. Midwest centered on Steinauer, Nebraska. This network is operated by the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, for the purpose of observing meteors and locating meteorites soon after impact. Each camera is programmed to make four three-hour exposures each night, and the 9X9-inch film (totaling 3.6 acres per year) is quickly scanned for nearly straight meteor tracks. Except for about 200 films used in conjunction with the Condon report to check UFO reports, the Prairie Network films have not been scanned for irregular UFO tracks or images, a job that would require at least 30 persons working full time.

Single all-sky cameras, photographing about 80 degrees down from the zenith on all sides, are used for broad sky-brightness measures but do not have sufficient resolution to detect UFOs. A large number were operated by international cooperation during 1957-58, and two or three are operated continuously in Czechoslovakia. The Canadians started operating a meteorite network similar to the Prairie Network in 1970, but their films have not been scanned for UFOs.

The National Aeronautics and Space Administration operates several artificial satellites equipped with optical TV cameras that radio image-data to ground-based receivers.

Two sets of satellites record cloud patterns for weather prediction, and they might detect bright, high UFOs. Other optical satellites used for astronomical observations look outward and have a very small chance of detecting small objects. Similarly, the telescopes used by astronomers at observatories all around the world have little chance of photographing a passing UFO. Two radar networks covering most of the United States and Canada are operated jointly by the U.S. and Canadian (civilian) Aviation Administrations and by the North American (military) Air Defense Command. Together, they track every airplane, balloon, rocket, satellite, or other moving object; but the task of sorting out UFOs from full-time records of the millions of other objects tracked each day would require an expensive and very special computer. It is probable that most of the radar targets not associated with scheduled aircraft, known balloon launches, and known rocket firings would be thunderstorms, air currents, and other complex meteorological phenomena; and a systematic search for UFOs would require hundreds of weather specialists.

Statistical studies.

The statistical studies of type 3 could be undertaken by psychologists if the UFO reports filed by Project Blue Book or other groups are systematized and recorded on punch cards or tape for use in an electronic computer. The difficulty here lies in the wide variety and incomplete nature of UFO soft data. None of the files contains all sightings, and the record of any one sighting usually omits several points of significance to sociological or psychological studies.

The sample of over 12,000 sightings is, however, large enough so that in the early 1970s psychologists were planning to sort the records into broad categories that could be statistically corrected for incompleteness and used to study mass hysteria, hysterical contagion, and possible causes of hallucination. Some of the hallucinations associated with UFO reports may be related to the so-called Isakower syndrome, wherein a drowsy person visualizes scenes of his remote past, which would account for apparitions and misidentifications.

Response of the public.

Psychologists are also interested in the strong emotions aroused by UFOs among the witnesses who sighted them, the public who read about them, and the scientists who evaluate reports. In addition to defending the validity of their reports, witnesses are usually somewhat "shaken" by their sightings, a reaction similar to that of religious experiences. The witnesses, however, are seldom active in organizing UFO study groups or in writing books and articles.

Public reaction ranges from excited curiosity to ridicule. The excitement is probably related to the extraterrestrial hypothesis, exemplified by the strong public interest since 1900 in possible intelligent life on Mars. Some of the emotion may derive from religious beliefs about terrestrial man's place in the universe or from ancient myths about the supremacy of angels over ordinary men. It often involves fear of extraterrestrial visitors.

The evidence for these psychological reactions is displayed in the 50 books and over 250 magazine articles written in the U.S. about UFOs since the first flying saucer was reported in 1947. U.S. public interest was indicated by some 30 UFO clubs and societies that sprang up in the 1950s and '60s. There were signs that this public interest was diminished following publication of the Condon report and the termination of Project Blue Book in 1969. The number of newspaper articles on UFOs significantly declined to a fraction of its peak of 1966.

The reaction of physical scientists has been centered on reluctance to change their systems of belief based on current physics and astronomy. The basic philosophical question raised by UFO reports is one of reality. Because of the confusing variety of evidence and the doubtful reliability of most reports, it has been difficult to apply accepted criteria of physical reality to UFOs themselves, but the psychological UFO phenomenon is certainly real.


L.E. CATOE, UFOs and Related Subjects: An Annotated Bibliography (1969), a very complete list of books and magazine articles published since 1950, with descriptive comments on each

E.U. CONDON, Scientific Study of Unidentified Flying Objects, ed. by D.S. GILLMOR (1969), a lengthy and poorly organized collection of chapters written by 36 members of the University of Colorado project, including detailed studies of 59 cases and reviews of 32 others, plus appendices reprinting earlier governmental reports and private studies

J. JASTROW, Error and Eccentricity in Human Belief (1963), a historical summary of popular misconceptions

CARL JUNG, Ein Moderner Mythus (1958; Eng. trans., Flying Saucers: a Modern Myth of Things Seen in the Sky, 1959), a sociopsychological analysis

DH. MENZEL and L.G. BOYD, The World of Flying Saucers (1963), an attempt to explain the wide variety of reports in terms of astronomical and meteorological phenomena, including many case descriptions and some physiological explanations

T. PAGE AND S. SAGAN, Physics and Psychology of UFOs: Proceedings of the AAAS Symposium, Boston, 1969 (1970), a collection of 15 speeches on various aspects of. UFOs, including expert analyses of photographs, radar detections, hallucinations, meteorological effects, extraterrestrial life, press reporting, and many unexplained cases

E.J. RUPPELT, The report on Unidentified Flying Objects (1956), a summary of explained reports received by the U.S. Air Force over eight years

JULES and J. VALLEE, Challenge to Science: The UFO Enigma (1966), a survey of reports that are difficult to explain in terms of natural phenomena.

The New Encyclopedia Britannica, 15th Edition, 1974-1984, Macropedia, Volume 18, pages 853-857


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