Boulder, ColoradoFebruary 1959

In February 1959, a photographer standing on Flagstaff Mountain near Boulder, Colorado, took what he thought was an ordinary scenic picture. When the film was developed, a white blob appeared on the negative, shaped like a classic flying saucer. The witness had seen nothing unusual in the sky when he snapped the photo around 5 p.m., but there it was.

The photograph circulated among UFO enthusiasts, and the witness eventually sent a copy to Dr. Donald Menzel at Harvard College Observatory, a scientist known for investigating UFO reports. Rather than accept the image as evidence of a spacecraft, Menzel suggested a mundane explanation: the bright blob might be a reflection of the sun off a building window. He urged the witness to return to the exact spot where he took the picture and look for any large windows that could have been catching the sun at the right angle.

Not until May did the witness have a chance to return to Flagstaff Mountain with clear skies. Using the original photograph as a guide, he retraced his steps and discovered that the Law Building of the University of Colorado stood directly in the area where the UFO appeared on the film. The building's large double west-facing window was positioned at the exact center of the blob. Though no reflection appeared in May, the witness calculated that in February, when the sun was at a different angle, the window could have reflected sunlight directly to his camera position if tilted just right. The sun's image was extremely bright, and the film had overexposed, causing the light to spread across the negative and create the illusion of a large, glowing object. When the witness reprinted the negative at increasingly dark exposures, the white blob shrank, and on the blackest prints, the fuzzy outline of a window frame became visible.

The Air Force evaluated this case as unknown. The full case file is reproduced below as held by the National Archives across 31 pages.