One of the most complex incidents in saucer history occurred early in August 1953 near Rapid City, South Dakota. Like the sightings the previous year at Bellefontaine, Ohio, and Port Huron, Michigan, the presence of a UFO seemed to be confirmed by several types of evidence. Trained civilian and military personnel on the ground and in the air observed an unknown visually and by radar. The blips on the ground radarscope were photographed and a plane’s gun camera took a picture. If a similar incident were to occur today, Air Force investigators would probably find the answer without difficulty. In 1953, however, they were less experienced and finally classified the case as “one of the best” Unknowns. It is clearly impossible to solve the mystery with absolute certainty after nearly ten years, because vital information is lacking. The original records are no longer on file. Few details are available except those in Ruppelt’s sketchy summary[VIII-3, p. 303 ff.], and some of these are inaccurate: the town of Black Hawk, for example, is not west, but northwest, of Rapid City. Although many questions of fact must therefore remain unanswered--exact times, directions, sequence of events--we offer here a highly probable explanation. The first report came at 8:05 P.M. M.S.T. when a spotter for the Ground Observer Corps in the town of Black Hawk telephoned the Air Defense Command post near Rapid City, approximately ten miles southeast of Black Hawk, to report an extremely bright light hovering low on the horizon to the northeast. The radar operators at Ellsworth Air Force Base had been working with a jet patrol flying west of the base. After receiving the phone call, they shifted the scope to scan the northeast quadrant of the sky and picked up an unidentified target moving slowly at about 16,000 feet. Although the controller wondered at first whether the target might have been due to weather, he decided after a few minutes that it was well defined, solid, and bright. Since the ground spotter had a visual target and the traffic controller had a radar target, he telephoned to compare notes on positions; as they were talking, the spotter interrupted the conversation to say that the light was beginning to move southwest toward Rapid City. Checking the radarscope and finding a fast-moving target the controller sent two of his men running outside to look at the sky. After a few seconds they reported that they could see a large bluish-white light moving toward them from the northeast. It made “a wide sweep” around Rapid City and then returned to a stationary position in the northeast where it had first appeared. (Unfortunately the account does not state clearly whether the “wide sweep” was observed visually or on radar.)