The geographical situation would have helped produce the illusion. Fargo lies at an elevation of about 900 feet and the land rises gradually to the west. Due west is Bismarck at 1670 feet. To the south lies a series of buttes, some of them as high as 3500 feet. Thus in the southwest where Jupiter was setting and where the UFO attacked from, the buttes would repeatedly have cut off the planet from view as Gorman maneuvered, so that the image would have seemed to race in and out and perform evasive actions, just as did the mirage of Sirius in Alaska (p. 60). Since Jupiter was very low, however, the buttes served to conceal it from the observers on the ground. [Illustration: _Figure 9._ Positions of refracted image of Jupiter from 9:00 to 9:29 P.M. at Fargo, North Dakota, on October 1, 1948. Azimuth measured north through east.] The times involved provide the last piece of the puzzle. The dogfight ended at about 9:27. The time of the geometrical setting of Jupiter was 9:25. The usual lag due to refraction is between two and three minutes (see Figure 9). The planet therefore remained visible for about two minutes longer. The image actually sank below the horizon and disappeared from view between 9:27 and 9:28, the same time that the UFO climbed straight up into the sky and disappeared. When Jupiter vanished, the unknown also vanished and did not return. Absolute proof of this solution is of course impossible. Nevertheless, the description of the UFO, its behavior, its direction, its time of disappearance--all are consistent with its identification as Jupiter. The Gorman case might reasonably be removed from the “Balloon?” category and listed as “Balloon plus planetary mirage.” _Jupiter through a Jet Trail_ Venus, Mars, and Jupiter seen under unusual conditions can mystify even the most hardheaded witness. Unrecognized air turbulence and increased scattering of the light can easily create the illusion of a flying saucer. An ex-army man, a trained observer with a good knowledge of physics and optics, reports the following unnerving experience[IV-11].