Caelum Incognitum — The interactive encyclopedia of ufology
Blue Book by the numbers
Cases, documents & milestones
Between 1952 and 1969, Project Blue Book logged 12,618 reports, of which 701 (about 5.6%) remained “unidentified” for lack of sufficient information. The rest were attributed to stars, aircraft, balloons, satellites or hoaxes. These figures prove nothing about the nature of the unexplained cases.