The Phoenix Lights mass sighting (March 13, 1997)

On the evening of March 13, 1997, thousands of people across the Phoenix metropolitan area reported seeing a formation of lights moving across the sky followed later by a second series of stationary lights. The event generated local, national, and international media coverage and remains one of the most famous mass UFO sightings in U.S. history. The U.S. Air Force later said the second group of lights were illumination flares dropped during training exercises at the Barry M. Goldwater Range, an explanation that remains debated by some witnesses and researchers.