Terre Haute, IndianaAugust 1959

On August 18, 1959, at 1310 (1:10 p.m.), a person in Terre Haute, Indiana witnessed an unusual object at the zenith of its angular flight (the highest point in the sky directly overhead). The object was shell-like in shape and traveled from southeast to northwest directly above a location near latitude 39 degrees 28 minutes and longitude 87 degrees 26 minutes. Most striking was a flash and a noise heard at the moment of observation that resembled frying. The witness detected no trail or impact sound.

The Air Force initially calculated that the object was traveling at an apparent velocity of 120,000 miles per hour at a height of 120,000 feet. Because the sighting was so brief and the information so limited, the U.S. Air Force eventually referred the case to NASA for expert analysis.

NASA's Theoretical Division concluded that the object was probably a bolide, a type of very bright meteor that explodes. An expert there explained that if an object traveled at the reported apparent velocity, it would need to be at an altitude of about 120,000 feet to reach actual meteoric speeds. The Air Force's Aerospace Technical Intelligence Center (ATIC) agreed. ATIC analysts worked out detailed calculations of the meteor's approach angle and velocity. They concluded that the meteor was probably approaching Earth at about a 75-degree angle, which would account for its southeast-to-northwest path. They also noted that the sound likely reached the witness a few seconds after the object disappeared, and that the witness may not have recalled the time gap between the sighting and the sound. The absence of a visible trail was consistent with behavior of slow-moving fireballs.

The Air Force officially rated this case as unidentified, though the file demonstrates that both ATIC and NASA believed the object was a bolide meteor. The full case file, consisting of 8 pages, is reproduced below as held by the National Archives.