When he resumed the chase he supposed that he had located the same object he had been following earlier--but the evidence suggests that he had picked up a different target. The unknown was going much faster than before, was at a much higher altitude, and shone with a steady brilliance instead of blinking off and on. In such a tense situation he could understandably have mistaken one strange light for another. Pursuing an apparently hostile unknown, less than a year after the still mysterious death of Mantell in a similar encounter, he might justifiably have been frightened. The most probable source of the second light is the planet Jupiter. The sun had set at 6:24 P.M. Following some three hours behind the sun, the planet had a magnitude of -1.7 and was thus brighter than Sirius, the brightest star. Shortly after 9:10 when the UFO began its violent maneuvers (the exact time is not known), Jupiter was very low in the southwest sky, between two and three degrees above the horizon, at a bearing of about 231 degrees. The UFO was also attacking from the southwest, as is shown by Gorman’s tactics: in trying to cut it off in circles to the left, he gradually moved to the southeast. The weather bureau records for that evening, obtained from radiosonde observations, show that temperature inversions existed both near the ground and at higher altitude. Thus conditions were ideal to produce a furiously twinkling planetary mirage. When a planet is close to the horizon this twinkling, together with the defocusing action of the earth’s atmosphere, can spread out the image so that it looks huge, with an apparent diameter as great as ten minutes of arc. Under such conditions, both the size and the intensity of the light fluctuate. When they diminish, the object seems to be racing away from the observer; when they increase, it seems to be rushing directly towards him on a collision course. The peculiar lens-like action of the atmosphere makes the image seem to be, not at infinity, but only a few hundred feet away from the observer. Seen through the distorting atmospheric lens, the image of Jupiter could have performed exactly as Gorman described: it would have darted back and forth, seemed to attack, retreat, and carry out the “controlled” maneuvers that actually depended partly on the movement of the plane itself. Gorman apparently assumed that he was dealing with a material object (as indeed he was in the beginning), and therefore did not consider the possibility that he was seeing merely an optical image.