Los Alamos Green Fireballs Incident

The Sightings

Beginning on December 5, 1948, bright green objects—subsequently termed "green fireballs"—were reported streaking horizontally across the sky over Los Alamos, New Mexico, and surrounding areas. Reports accumulated through December 1948 and January 1949, with witnesses including airline pilots, federal agents, and military personnel.

The initial December 12, 1948 sighting was officially characterized as "most certainly not a conventional meteorite fall." Witnesses described a fireball that appeared "in full intensity instantly," maintained constant brightness during flight, traveled on a nearly horizontal path contrary to typical meteor behavior, and broke into "bright green" fragments at the end of its trajectory.

The 1949 Scientific Conference

On February 16, 1949, a classified conference marked SECRET and titled "Aerial Phenomena" was convened at Los Alamos Scientific Laboratory. Attendees included some of the nation's most prominent physicists and scientists:

• Dr. Edward Teller (hydrogen bomb developer, theoretical physicist)
• Dr. Norris E. Bradbury (Los Alamos Laboratory director)
• Dr. Lincoln LaPaz (leading meteor expert)
• Dr. Frederick Reines (Nobel Prize-winning physicist)
• Dr. Joseph Kaplan (geophysicist)

The attendees debated multiple explanations for the phenomenon. Dr. Teller proposed an "electron phenomenon" as a possible explanation if the objects were not physical. Other participants, including Kaplan, suggested natural meteors entering the atmosphere at a shallow angle. Remarkably, Army participants confirmed that the green fireballs had been formally classified alongside flying discs within Project Grudge (1948–49), the U.S. Air Force's official UFO investigation program.

Despite the assembled expertise, the conference failed to reach a definitive conclusion, though the group remained skeptical of extraterrestrial explanations.

Project Twinkle Investigation

The conference led directly to Project Twinkle (1949–1951), a U.S. Air Force initiative to systematically capture data on the fireball phenomenon through a network of observation posts and photographic surveillance stations. The plan called for three cinetheodolite (precision tracking camera) stations near White Sands, New Mexico, to triangulate and photograph future sightings in detail.

However, Project Twinkle suffered from budget constraints and equipment shortages. Only one cinetheodolite station was ever constructed, and it was repeatedly relocated in an attempt to intercept sightings—always unsuccessfully. The project was discontinued after two years without capturing definitive evidence.

Declassification and Historical Significance

The full transcript of the February 1949 conference and supporting documents remained classified until the Trump administration's Pentagon UAP declassification initiative in July 2026. The release of these records—part of the fourth batch of declassified files—revived public and scholarly interest in one of the earliest Cold War-era mysteries involving unexplained phenomena near America's most sensitive atomic facilities.

The incident raised Cold War-era concerns about potential Soviet reconnaissance or a genuine unknown phenomenon operating near nuclear weapons research installations. That the U.S. government deemed the matter significant enough to convene Manhattan Project physicists underscores the seriousness with which officials regarded the sightings.