Evolving Classifications of Unidentified Aerial Phenomena: From Hynek's Close Encounters to Global Standards

To the point

Unidentified aerial phenomena are studied with progressively scientific classifications that started with J. Allen Hynek’s Close Encounters (CE1–CE3, with CE4 for abductees) during Project Blue Book, were broadened by Jacques Vallée to include psychological and sociological factors, and now stress careful evidence—where and how seen, who saw it, what was observed, and any physical traces—across classic sighting types, while groups like the Center for UFO Studies push peer‑reviewed classification, debates about extraterrestrial or abductee explanations continue, and researchers look to better sensors, AI, and global data sharing to create a universal framework.