Chitose-Hokkaido, Japan, December 1957December 1957

On December 12, 1957, more than a dozen military personnel stationed at Chitose Air Base in Hokkaido, Japan, observed a very bright object in the southwestern sky for about an hour and twenty minutes. The object appeared circular and greenish-white, changing to yellow or white with an orange glow. It was so unusual that two F-86 fighter jets were scrambled from Misawa Air Base to intercept it.

The radar operators tracking the object from the ground reported it was moving at speeds up to 550 knots, at altitudes between 17,000 and 19,400 feet. The pilots of both aircraft reported seeing the bright light, but they lost track of it before they could close in for a close look. One pilot said the object faded from radar while he was still 90 nautical miles away. Not long after the interception attempt failed, the ground station discovered that a bad crystal in their radar equipment might have caused the signal to disappear.

About two or three days later, photographs were taken of what was believed to be the same object. However, when Air Force photo analysts examined the prints, they found serious problems. The photographs showed a fuzzy white light that could have been caused by a time exposure (keeping the camera shutter open for several seconds while the object moved). The analysts noted that the image sizes and movements shown in the three photos did not match what would be expected. They concluded it was doubtful that the photograph showed the same object observed earlier.

In their final analysis, Air Force investigators noted that the visual observations were made by reliable witnesses and the radar data was solid, but too many contradictions existed in the data to reach a firm conclusion about what had been sighted. The file indicates the case remained unexplained. The full case file is reproduced below as held by the National Archives, spanning 50 pages.