23 mi S Of Joliet, IllinoisMay 1960

On May 31, 1960, observers near Braidwood and Joliet, Illinois spotted a bright object in the night sky. The main witness, a local official with strong credibility, watched a brilliantly white object with an irregular upper portion for more than six hours. He described it as roughly the size of a pea held at arm's length, with a faint amber beam of light trailing from its lower left side. At times, the object appeared to swing back and forth slowly, like a pendulum, then would close down to a point of light before disappearing entirely.

An amateur astronomer about four miles away observed the same phenomenon through a telescope. He identified it as the planet Jupiter, which he studied with a 120-power reflector telescope. Two other civilian observers in the area also reported seeing a bright, steady object in roughly the same direction on the horizon. The two main observation points were roughly 32 miles apart.

An Air Force investigator from Chanute Technical Training Center interviewed the witnesses and consulted encyclopedic references on Jupiter's properties. The investigator noted that Jupiter's high reflectivity, its yellow-orange color, and its four visible moons all matched the witnesses' descriptions. The encyclopedia sources confirmed that Jupiter was exceptionally bright at that time, close to Earth in its orbit and at its yearly maximum brightness. The file concludes the object was probably the planet Jupiter, though one encyclopedia entry was also consulted on whether Saturn could have been the explanation.

The full case file, comprising 45 pages as held by the National Archives, is reproduced below.