#5. Project Sign (1947)
Project Sign was the first of a series of investigations into the existence and legitimacy of unidentified flying objects. The project was the first to make a comprehensive list of the factors defining an unidentified flying object which include color, shape of the object, speed of flight (usually around 300 knots), whether or not the object left a smoke trail, agility and maneuverability of the object, and absence of sound. This morphed into a “check list” of sorts for UFO and alien enthusiasts and is referenced for UFO sightings to this day. But the government didn’t really take kindly to the direction in which Project Sign was moving, since it was displaying a clear bias towards aliens as the cause of UFO’s as opposed to looking into more objective, logical explanations or natural causes.