Cases where an investigation or a consensus of independent analysts named a specific conventional cause - aircraft, flares, balloons, launches, astronomical objects or hoaxes. They stay in the archive with the explanation attached.
8 documented cases currently classed as explained, spanning 1561 to 1977. 2 of them involved military witnesses or sensors. 5 have declassified government records, with 10 source documents linked in total.
Highest-credibility cases: Canary Islands UFO (1976, scored 8/10), Mantell Incident (1948, scored 8/10) and Tunguska Event (1908, scored 8/10).
How a case is classed: resolution criteria
A massive jellyfish-like luminous object hovered over Petrozavodsk, prompting the Soviet government to establish official UFO research programs.
Thousands across the Canary Islands witnessed a massive luminous sphere; the Spanish Air Force investigation found no conventional explanation.
Captain Thomas Mantell died pursuing a large metallic UFO over Kentucky, becoming the first pilot death attributed to a UFO chase.
Three days before the Kenneth Arnold sighting, harbor patrolman Harold Dahl reported six doughnut-shaped craft ejecting molten material near Puget Sound. Two investigating officers later died in a plane crash.
A 10-15 megaton airburst flattened 2,150 km² of Siberian forest with no impact crater - the first modern aerial anomaly to provoke published speculation about extraterrestrial craft.
Japanese fishermen in 1803 discovered a strange rounded vessel with crystal windows carrying a mysterious woman who could not communicate, documented in four separate Edo-period texts with illustrations resembling modern flying saucers.
Large black spheres were observed in the sky over Basel, documented in a gazette broadsheet similar to the Nuremberg event five years prior.
Residents of Nuremberg witnessed an apparent aerial battle of spheres, cylinders, and crosses, documented in a famous 1561 woodcut broadsheet.