Philadelphia, Pa., May 1959May 1959

On the night of May 15, 1959, a Philadelphia resident watching the sky from his home near the Pennsylvania Turnpike Bridge saw a bright orange object that looked like an inverted dish with a structure on top like a diving bell. The object appeared roughly the size of an egg held at arm's length. The observer first spotted the object between 1:30 a.m. and 3:00 a.m., positioned between 20 and 30 degrees above the horizon.

Over the course of about an hour and a half, the observer saw the object twice, each time for approximately four minutes. During these sightings, the object moved up to about 40 degrees above the horizon and down to about 15 degrees, traveling parallel to the Earth's horizon from right to left and left to right. The object glowed, then faded completely, reappeared, and faded again. The observer watched with his naked eye first, then switched to a telescope with a four-and-a-half-inch reflector. The sky was clear to slightly cloudy with 15 miles of visibility.

The Air Force investigation quickly found a likely explanation. A U.S. Navy F8U photo aircraft was flying in the area on the same night, dropping flash flares with 250 million candlepower for a photography mission. Local radio stations in Philadelphia had announced the planned mission in advance. When the Air Force contacted the control tower at North Philadelphia Airport and the operations officer at Johnsville Naval Air Station, officials confirmed that the Navy aircraft had been dropping these extremely bright flares in the general area and at the times reported. The observer also provided four color photographs he claimed to have taken during the sighting.

The Air Technical Intelligence Center concluded that the photographs and sightings likely showed Navy flares. The full case file, consisting of 13 pages as held by the National Archives, is reproduced below.