UNIDENTIFIED FLYING OBJECTS (UFO)

Almost every civilization that has kept a written history has recorded the sighting of strange objects and lights in the skies. Today, unexplained aerial phenomena are generally referred to as unidentified flying objects or flying saucers.
Descriptions of UFOs have ranged from glowing wheels to colored balls of light to cigar-, disk-, or crescent-shaped objects. One of the first well-documented UFO sightings occurred in 1561 in Nuremberg, Germany. A broadsheet published that year describes red, blue, and black balls or plates, crosses, and tubes that appeared to battle each other in the sky over the city.
The term flying saucer was coined in 1947. A businessman named Kenneth Arnold told reporters that while flying a private airplane near Mount Rainier in Washington he saw nine objects flying over the mountain in formation and at a speed of more than 1,600 miles (2,500 kilometers) per hour. Arnold described the objects as moving like "a saucer skipping across the water." After that first report, Arnold's description was shortened and it soon became popular to call all UFOs flying saucers.
The United States government has records of thousands of UFO sightings, including photos of alleged UFOs and interviews with people who claim to have seen them. Since UFOs were considered a potential security risk, the report on these sightings was originally classified as secret. When the report was later declassified it showed that 90 percent of all UFO sightings could be easily explained. Most of the sightings turned out to be celestial objects, such as stars or bright planets like Venus, or atmospheric events such as auroras or meteors falling through the atmosphere. Many other sightings turned out to be such objects as weather balloons, satellites, aircraft lights, or formations of birds. Often these sightings were accompanied by unusual weather conditions.
In 1948 the United States Air Force began the government's first official UFO panel, Project Sign, which studied 243 sightings. It was replaced by Project Grudge, which investigated another 244 sightings. In March 1952 the most ambitious of the UFO panels, Project Blue Book, was organized by the Air Force. The panel employed a number of scientists, including physicists, engineers, meteorologists, and an astronomer. Project Blue Book had three main goals: to explain all reported sightings of UFOs; to decide if UFOs posed a threat to the national security of the United States; and to determine whether UFOs were using any advanced technology that the United States could use.
By the mid-1960s UFO reports were more numerous than ever. For the first time they were coming in regularly from places outside the United States, including Canada, Sweden, the Soviet Union, and Australia. In February 1966 another UFO panel was convened. Like the others, this panel determined that the vast majority of UFO reports were either natural phenomena or outright hoaxes.
A few scientists publicly disagreed with the panel's conclusions. This group, which included James E. McDonald, a meteorologist at the University of Arizona, and J. Allen Hynek, an astronomer at Northwestern University, maintained that since a few of the most reliable UFO reports had never been clearly explained, this was definite proof that Earth was being visited by extraterrestrials.
The dissenting scientists' opinion was received coldly by the mainstream scientific community. In 1968 the United States Air Force asked Edward U. Condon, a physicist at the University of Colorado, to head a panel studying the extraterrestrial hypothesis (see Extraterrestrial Life). The committee's final report, 'A Scientific Study of UFOs', which covered detailed investigations of 59 UFO sightings, was reviewed by a special committee of the National Academy of Sciences and released in early 1969. The 37 scientists who contributed to the report interviewed UFO witnesses and studied physical and photographic evidence. The report, also known as the Condon Report, concluded that not only was there no evidence of extraterrestrial control of UFOs but also that no further UFO studies were needed.
Based on the recommendations of the Condon Report, Project Blue Book was closed in December 1969. By the time the project was disbanded, it had amassed some 80,000 pages of information on 12,618 reported UFO sightings and events, each of which was ultimately classified as either "identified" with a known astronomical, atmospheric, or artificial phenomenon, or as "unidentified," including cases in which information was insufficient.
The only other official and relatively complete records of UFO sightings were maintained in Canada, where they were transferred in 1968 from the Canadian Department of National Defense to the Canadian National Research Council. The Canadian records had totaled about 750 sightings and events in the late 1960s. Less complete records have been maintained by scientists in Great Britain, Sweden, Denmark, Australia, and Greece.
Since the closing of Project Blue Book, the United States government has not had any official programs for studying UFOs. In 1973, however, a group of American scientists organized the Center for UFO Studies (now the J. Allen Hynek Center for UFO Studies, in Chicago, Ill.). It is one of several private groups that continue to study the phenomenon.
According to a United States Air Force guide published on the subject, the reliability of witnesses is one of the main considerations in all UFO sightings. Also of note are the number of witnesses, how long they saw the UFO, how far away they were from the UFO, and the weather conditions at the time of the sighting. One of the most common features of UFO reports is that witnesses often insist that the objects they saw were under intelligent control. People frequently come to this conclusion because, like Kenneth Arnold, who saw flying saucers above Mount Rainier, they believe they see objects flying in formation or toward another object or changing direction or speed dramatically.
People have a natural desire to explain and understand everything they see. This is why visual sightings of UFOs are the least reliable. The unaided human eye can be tricked to the point of hallucination. A bright light, such as the planet Venus, often appears to move, though a clamped telescope or a sighting bar shows it to be fixed. A visual impression of distance is also unreliable because it is based on an assumed size. Reflections from windows or eyeglasses may provide superimposed views. Optical defects can turn point sources of light into apparently saucer-shaped objects. Such optical illusions coupled with a desire to interpret visual images account for many UFO reports.
Radar sightings, while more reliable in certain respects, do not provide the information necessary to discriminate between physical objects and such natural phenomena as meteor trails, tracks of ionized gas, rain, or thermal discontinuities. Furthermore, several effects can give false radar echoes: electronic interference, reflections from ionized layers or clouds, and reflections from a region of humidity--for example, a cumulus cloud.
Even so-called contact events--in which activities besides sighting were reported--have been found most frequently to involve dreams or hallucinations. The reliability of such reports depends heavily on whether there were two or more independent witnesses present.