Atmospheric sound channels

A second statement said the debris was just a weather balloon. The media accepted this version, although UFO enthusiasts still believe the Pentagon has a crashed extra-terrestrial spacecraft.

The second explanation was correct if misleading. It was an exotic weather balloon from a classified military programme, the existence of which was not revealed until 1994. The secret Project Mogul involved a cluster of meteorological balloons designed to carry microphones to a high altitude.