UFOs: Natural Explanations
Posted on April 16, 2018 by jessiekratz
From 1947 to 1970, the United States Air Force conducted investigations into the increasing number of unidentified flying object (UFO) sightings throughout the United States. The purpose of the investigations was to assess the nature of these sightings and determine if they posed any potential threat to the U.S.
Three successive projects were created to carry out these investigations: Sign, Grudge, and Blue Book.
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