Wilmington, DelawareAugust 1961

On the evening of August 25, 1961, two observers in Wilmington, Delaware, reported seeing an unusual object in the sky. At about 8:00 p.m., they spotted what appeared to be a bright white object with an orange crescent and a red dot attached to it. The object looked about three to four times brighter than the star Arcturus, which was visible in the west-northwest section of the sky. The witnesses observed it through a six-inch reflecting telescope at forty times magnification.

About seven minutes after they first saw the object, it exploded. Without the telescope, the witnesses saw it break apart into many pieces and release what looked like a small amount of smoke. The fragments gradually faded and became invisible after roughly ten minutes. The explosion itself was not seen through the telescope, as the observers had been trying to photograph the object at that moment. The photographs did not turn out because there was not enough light.

The Air Force asked the witnesses to complete a detailed questionnaire and conducted a follow-up investigation. Based on the description of the object's appearance and behavior, officials concluded that the sighting had probably been a radiosonde weather balloon (a balloon equipped with instruments to measure atmospheric conditions). The file notes that the white, shiny appearance would be expected when sunlight reflects off a balloon from a certain angle, especially when the balloon is between the observer and the setting sun. The red light was likely an anti-collision beacon, which is attached to weather balloons at high altitude. The witnesses themselves, in a 1963 letter following up on their report, agreed that a weather balloon was the most probable explanation, though they wanted official confirmation.

The complete case file, including witness questionnaires and official correspondence, is reproduced below as held by the National Archives across 18 pages.