2 Mi E Of Mount Prospect, Ill, May 1958May 1958

A woman driving home from work near Mount Prospect, Illinois, saw a small, bright object in the evening sky on May 21, 1958. She described it as bullet-shaped, about the size of a quarter, with a shimmering gold color that was very bright. She spotted it while stopped at a traffic signal, driving in a southwest direction into the sunset. Once her car began moving again, she lost sight of the object.

The Air Force interviewed the witness the next morning. At the time of the sighting, weather conditions were clear with no clouds. The 755th Aircraft Control and Warning Squadron, which operated radar in the Chicago area, reported no contact with any unidentified objects that evening and confirmed there were no aircraft in the vicinity of O'Hare International Airport at the moment of the sighting.

Investigators noted that the sighting occurred just as the sun was setting, which could cause optical illusions. Since the witness was driving directly into the sunset when she saw the object, the investigators suggested the bright object might have been a reflection or refraction of sunlight. The investigator wrote in his report that the sighting "magnified the possibility of an optical illusion." They also considered whether it could be a recently launched Russian satellite or rocket assembly, though this was listed as a lesser possibility.

The case was officially evaluated as "possibly balloon," though the file shows investigators leaned toward an optical illusion caused by the setting sun. The case file is reproduced below as held by the National Archives across 10 pages.