This sighting has remained technically an unknown chiefly because the descriptions fail to give the necessary information. What direction did the object come from? How long was it in sight? What balloons had been released in the area that day? At what time? What were the winds at high altitudes? The winds at low levels were from the west, and at altitudes from 20,000 to 50,000 feet they were from the east; but what were they in the region above 70,000 feet, the probable location of the object? Even without these facts, a reasonable explanation can be offered: the unknown was a radiosonde balloon that burst at a high altitude. The sun was low on the western horizon. A balloon at a great height reflects the sun brilliantly from its rubber or plastic skin and gleams like a giant metallic sphere. These balloons usually soar to 70,000 to 90,000 feet before they burst from the cold. The fragments then disperse in an impressively uniform pattern, and may disappear quickly. The radiosonde package and attached parachute fall rapidly at such heights. They are not noticed by the witnesses because the chute usually does not open fully until after the package has fallen some distance into the beginning twilight near the earth’s surface. This explanation of the “stack of coins” cannot be proved, of course, but every detail of the incident is consistent with the behavior of a bursting balloon[III-2]. _Jets and Contrails_ Weather balloons are not the only air-borne objects that have been mistaken for interplanetary craft. Flying saucers reported over Durango, Colorado, early in August 1952 turned out to be four T-33 Air Force jets flying at 30,000 feet, so high that no sound reached the ground.