July 23, 1952: Three F-94 Starfire fighter jets cruised at 644 miles per hour in the skies above Pottstown, Pennsylvania. Fighter pilots reported seeing a silver large pear-shaped object with no visible means of propulsion. Two smaller, darker objects also appeared to run circles around the larger craft for approximately 30 minutes. The alleged encounter 40 miles northeast of Philadelphia was one of 12,618 incidents detailed and investigated by Project Blue Book, a government program to assess the credibility and potential threat of unidentified flying objects. Six decades later, the U.S. military is once again publicly investigating UFOs, and is due to issue a report to Congress on what it now terms unidentified aerial phenomenon. In recent years, fighter pilots and stealth ships have reported strange objects off the Atlantic and Pacific coasts. Yet hundreds of other phenomena remain a mystery in the skies above Pennsylvania.