Grand Junction, ColoradoSeptember 1960

On September 29, 1960, civilian observers in Colorado and New Mexico reported seeing an unusual flying object. People at the Federal Aviation Administration stations in Grand Junction and Eagle, Colorado, along with observers in Farmington, New Mexico, all spotted the object. Many other people in the area reported seeing it too.

The object was described as round and flashing red, green, and white light. Witnesses at Grand Junction saw it remain mostly stationary in the sky for about 20 minutes, then move toward the southwest. The entire sighting lasted 40 minutes. Using an inclinometer (a device to measure angles), observers estimated the object was about 37 and a half miles high. The object itself appeared as a square light inside a round circle.

To narrow down the location, witnesses at Grand Junction and Farmington used a theodolite (an instrument to measure angles) to triangulate the object's position. Their calculations suggested it was somewhere around Gunnison, Colorado. Interestingly, a B-52 aircraft was refueling nearby and reported being able to see the object. When the aircraft flew toward the area afterward, the pilot found nothing there.

The Air Force examined weather data from the sighting date and found evidence of a temperature inversion in the area, a layer of warm air sitting above cooler air near the ground. According to the Air Force's analysis, light bending through such an inversion can create optical effects sometimes called "looming mirages," which make distant objects appear higher and more dramatic than they actually are. The Air Force concluded that these atmospheric conditions probably caused ordinary objects to be misidentified as something unusual. The complete case file runs 9 pages and is reproduced below as held by the National Archives.