Circular UFO sighted by fighter pilots in 1958

Summary

In April 1958, two F-100 fighter pilots reported seeing a circular object the size of a pea, white in color, at a high altitude above a weather balloon. The sighting occurred halfway between Fresno and Merced, California, while the pilots were investigating the balloon. The object made a 180-degree turn and then quickly streaked toward the Pacific Ocean. Although a U-2 aircraft was noted in the general area, its connection to the event was not confirmed.

The official conclusion pointed to an aircraft, possibly the U-2, though the pilots did not identify it directly. The difficulty of estimating altitude with the naked eye from the air complicated the evaluation. The report highlighted the observers' reliability and noted no conventional explanation for the sighting. The case remains an unresolved mystery in UFO files.