UNIDENTIFIED FLYING OBJECT

also called flying saucer any aerial object or optical phenomenon not readily explainable to the observer. UFO's became a major subject of interest with the developments in aeronautics and astronautics following World War II. In 1948 the U.S. Air Force began maintaining a file of UFO reports called Project Blue Book. 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 (Pasadena), 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 meteorologic phenomena (e.g., bright planets, meteors, auroras, ion clouds) or with aircraft, birds, balloons, searchlights, hot gases, and other phenomena, sometimes complicated by unusual meteorologic conditions. The publicity given to early sightings in the press undoubtedly helped stimulate further sightings not only in the United States but also 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 (Tucson) meteorologist, and J. Allen Hynek, a Northwestern University (Evanston, Ill.) astronomer, concluded that a small percentage of the most reliable UFO reports gave definite indications of the presence of extraterrestrial visitors. This sensational hypothesis, promoted in newspaper and magazine articles, met with prompt resistance from other scientists. The continuing controversy led in 1968 to a UFO study sponsored by the U.S. Air Force and conducted at the University of Colorado under the direction of E.U. Condon, a noted 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. Condon's own Conclusions and Recommendations firmly rejected ETHthe extraterrestrial hypothesisand declared that no further investigation was needed. This left a wide variety of opinions on UFO's. A large fraction of the American 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 favoured continuing investigation on the grounds that UFO reports are useful in sociopsychological studies. In 1973 a group of American scientists organized the Center for UFO Studies in Northfield, Ill., to conduct further work. Official records of UFO sightings and events. By 1969 Project Blue Book 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. The project, however, was terminated in December 1969 on the basis of the conclusions of the Condon Report. 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 Canadian National Research Council. The Canadian records totaled about 750 in the late 1960s. Less-complete records have been maintained in Great Britain, Sweden, Denmark, Australia, and Greece.