Investigators from a nearby Air Force Base interviewed the witnesses, who were obviously competent and reliable. All agreed that the unknown had been a bright, silvery, metallic-looking object that seemed to glisten or flicker in the sun; that it was roughly oval or indeterminate in shape; that it was solid and tangible, but not a conventional aircraft or balloon; that it made no sound, showed no exhaust or vapor trail; that it was in view roughly fifteen minutes, and disappeared gradually by “blotting out” or fading. All but one of the witnesses agreed that the skies had been absolutely clear and cloudless; one stated that, although the day was clear, a very slight haze existed over the mountainous region where the UFO appeared. In spite of this general agreement, certain significant discrepancies became evident. The pursuing pilot stated that the object had moved up and away from him at incredible speed, as though it were controlled. The ground observers, however, did not see any movement by the UFO. Most of them reported that it remained stationary as though it were suspended in the air; a few said that it vanished at intervals, only to reappear a few seconds later in another place. Most of the time, they agreed, it just hung in the sky until it faded from view. By analysis of these clues, ATIC was able to solve the mystery. According to the local weather bureau, the sky had been clear with visibility unlimited, but there had been very thin cirrus clouds, a layer of minute ice crystals suitable for producing a mock sun. A sundog would also account for the contradictory statements about the UFO’s motion. Since the ground observers remained in one place, their position relative to the sundog did not change and it seemed to remain stationary. The pilot, however, was in a moving plane and changing his position relative to the UFO; hence it seemed to move rapidly away from him. In the same way a rainbow seems stationary to a person who merely stands and watches it. But if he begins to chase it, hoping to catch up and perhaps find the legendary pot of gold, the rainbow seems to move away and elude its pursuer. The pilot’s belief that the UFO had exhibited fantastic speed was, according to his own statement, an inference based on the fact that the UFO quickly dwindled, became very small, and vanished. It disappeared, however, not because it was speeding away at thousands of miles an hour, but because of a change in the relative positions of sun and ice clouds that produced the sundog in the first place. One final point nailed down this explanation. The angular distance between sun and UFO was exactly that to be expected between sun and mock sun, at that time and place.