Between Wendover And Salt Lake City, UtahSeptember 1960

On September 23, 1960, a truck driver traveling east between Wendover and Salt Lake City, Utah, spotted an unusual object in his rear view mirror. He first saw it as a pear-shaped object about the size of a silver dollar, hovering roughly 31 degrees above the horizon to the northwest. As the object descended, it appeared to grow larger and changed shape, becoming more circular. Its color shifted from silver to a pulsating red-orange that grew brighter and more intense as the object moved away.

The driver watched the object for about 42 minutes as it traveled southward, then southwest. He noted that its speed was extraordinarily fast, fast enough that it would have made a jet aircraft look as if it were standing still. The object appeared to remain at roughly the same height above the horizon throughout the sighting, though the driver continued to observe it through his truck's rear view mirror and did not stop the vehicle.

Air Force investigators noted that weather conditions at the time were clear with good visibility. They also observed that lenticular clouds (lens-shaped cloud formations caused by wind flowing over terrain) were common in the area and could create illusions at sunset. Additionally, Jupiter and Saturn were both visible above the horizon at dusk in late September. A weather balloon released from Salt Lake City that afternoon could also have been in the relative position described by the observer.

Captain H. L. Gilbert, the Safety Officer at Tooele Army Depot, reviewed the evidence and concluded that the object was most likely one of four possibilities: a weather balloon, an airplane, a planet, or a lenticular cloud. The Air Force's official evaluation listed "probably balloon" as the assessment. The full case file, consisting of 8 pages as held by the National Archives, is reproduced below.