Black triangle over Philadelphia 1958

Summary

A civilian observer in 1958 described a flat, black triangular object with rounded corners, the size of a shirt button held at arm’s length. The object appeared east of the horizon, ascended for five minutes in a straight line nearly to the zenith, hovered briefly, then descended to about 45 degrees. It then moved westward and disappeared. The observation lasted 15 minutes with no visible trails or sounds.

Investigators concluded it was a balloon, though the report notes inconsistencies. The witness, a 38-year-old technical illustrator, used no optical aids and weather conditions were clear. Despite the unusual description, the flight characteristics matched a balloon released in the area.