Pilots chase a stratospheric balloon over Brioude in 1956

Summary

On September 20, 1956, two pilots in flight spotted an aluminum-colored spherical object moving slowly through the sky. Intrigued, they tried to close in but could barely reduce the distance. After giving up the pursuit they consulted the Puy-de-Dôme observatory, which confirmed the presence of a translucent spherical balloon visible all day at roughly twenty kilometers altitude. The balloon drifted slowly and disappeared from sight at nightfall. GEIPAN classified it as an unidentified stratospheric balloon. The pilots' inability to close the gap, even at high altitude, supports this hypothesis and highlights the optical illusion created by such a distant object.