Green Fireballs: The 1949 Los Alamos Mystery in Declassified Files

On the night of Dec. 12, 1948, Lincoln LaPaz looked up over northern New Mexico and saw something he could not explain. LaPaz was no casual stargazer. He ran the University of New Mexico’s meteor research program and had tracked fireballs for years.

What he saw broke every rule he knew. The light appeared at full brightness all at once, held steady, slid along a nearly flat path, then burst into bright green fragments. It made no sound.

Within weeks, the green fireballs had the attention of the FBI, the Army, the Atomic Energy Commission and the men who built the atomic bomb. Nearly eight decades later, the government’s own files show they never fully solved it.

Green Fireballs Over the Atomic Southwest

The first reports came from the air. In December 1948, airline pilots and military aircrews over New Mexico described a bright “green ball of fire” crossing the sky. More reports followed from ground observers, many of them employees at Los Alamos and nearby military installations.

The locations are what alarmed officials. New Mexico in 1948 held Los Alamos, where the first atomic bombs were designed; Sandia Base, where weapons were assembled and stored; and Kirtland Air Force Base next door in Albuquerque. A top secret FBI memo from early 1949 recorded unexplained phenomena near Los Alamos on at least nine dates in December 1948 alone, according to records reviewed by The Taos News.

That memo concluded the objects were not meteorites. It said they were either unknown natural phenomena or man-made. Another FBI memo raised the possibility that they were tied to secret U.S. guided-missile work. In January 1949, the Army’s Fourth Army intelligence chief in Texas floated a darker idea: foreign radiological warfare experiments.

It was the opening of the Cold War. The Soviet Union had not yet tested its first bomb, and nobody wanted to guess wrong about strange lights over America’s nuclear crown jewels.

The Secret Los Alamos Conference of 1949

At 1 p.m. on Feb. 16, 1949, a group gathered in conference room P-162 at the Los Alamos Scientific Laboratory. The meeting was classified Secret. Its subject line read “Aerial Phenomena.”

The attendee list reads like a Cold War who’s who. Laboratory director Norris Bradbury was there. So were physicists Edward Teller and Frederick Reines, an FBI agent, an Atomic Energy Commission security official, officers from the Fourth Army and a commander from the Armed Forces Special Weapons Project. LaPaz came as the outside expert.

The transcript, declassified in 1975, was released again this summer as file DOE-UAP-D004 in the Pentagon’s fourth PURSUE batch. The full document is posted in the Department of War’s PURSUE archive.

What LaPaz told the room

Army Capt. Neef opened by admitting the military had no idea what the objects were. He noted LaPaz had been helping since December without pay.

LaPaz walked the group through how real meteorites behave, then explained why the green fireballs did not fit. According to Newsweek’s review of the released transcript, he described three tracked paths, each low, roughly 8 to 10 miles up, moving at nearly constant speed over long horizontal distances.

Big meteorite falls, he noted, usually make enough noise to frighten people and animals on the ground. LaPaz called the silence of the green fireballs “the most implausible feature of all.”

Then there was the color. Observers placed it between about 4,900 and 5,300 angstroms, clustering near 5,218, a vivid green. LaPaz likened it to copper salts burning in a lab burner. Meteorites, he said, carry only traces of copper.

The January 30 fireball

One event stood out. On Jan. 30, 1949, more than 100 people across New Mexico and West Texas reported a green fireball. It appeared southwest of Amarillo and vanished near Lubbock. Trained observers gave direction and elevation readings within minutes, which let LaPaz plot its path.

Teller pressed LaPaz on the brightness and duration. The scientists left without a consensus. Edward Ruppelt, who later ran the Air Force’s Project Blue Book, wrote that more quiet meetings on the subject followed later in 1949.

209 Sightings and a Trail of Copper Dust

The scale of the problem came into sharper focus in May 2026, when the second PURSUE release included a 116-page Sandia Base dossier. The Pentagon said it logs 209 sightings of “green orbs,” “discs” and “fireballs” near the base between 1948 and 1950.

The file describes objects that appeared to maneuver, vanish or explode. It also includes investigations into residual copper powder found at several sites, according to Newsweek’s coverage of the release. Copper fit LaPaz’s color theory neatly, which is part of why the detail still gets passed around today.

An August 1950 FBI memo put the count at about 150 observations near New Mexico installations since 1948. The exact total depends on who was counting and what they counted, but the numbers point the same way: this was not one strange night.

Stucci Media has tracked each batch of the 2026 files, including a rundown of what the Pentagon’s UFO file drops have actually shown so far.

Project Twinkle: Cameras on the Desert

The Air Force responded the way the military often does: it built a watch. Project Twinkle set up observation posts to triangulate and photograph the fireballs. Reports clustered around Holloman Air Force Base and the small town of Vaughn, about 150 miles to the north, so instruments went to Vaughn first and then back to Holloman in late 1950.

The plan relied on Askania phototheodolites, precision tracking cameras run by a contractor, Land-Air Inc., plus grating cameras that could split light into its colors. In theory, a single good photo could have revealed what was burning.

Reality got in the way. The grating cameras sat mostly unused after their operators were reassigned for the Korean War. An electromagnetic monitoring setup was dropped because sightings were too rare to justify roughly $50,000 a year. Some lights were seen during missile and V-2 launches in August 1950, but the crews never got a proper triangulated fix.

The Project Twinkle final report, dated Nov. 27, 1951, called the results “essentially negative.” It recommended no more spending and put the effort on standby.

Green Fireballs Still Light Up the Sky

Green fireballs did not stop in 1951. They are still reported, and now they are routinely caught on dashboard cameras, doorbell cameras and observatory sky cameras.

On the evening of Sept. 14, 2011, a bright green fireball startled skywatchers across the Southwest, the same region that spooked the Cold War investigators. In February 2017, a huge green fireball lit up the Midwest sky and was captured on video by people across several states, NPR reported. Sightings have also been logged in Japan, Australia, West Virginia and Tennessee.

The difference today is the camera. A single clear video can be matched against meteor networks within hours. In 1949, LaPaz had eyewitness sketches, phone calls and his own notebook. Modern footage has helped scientists study how bright meteors behave, and it has also made clear how strange a big green bolide can look to someone who has never seen one.

What Skeptics Say

The strongest ordinary explanation is the one LaPaz worked hardest to rule out: meteors, specifically bright fireballs, also called bolides.

• Green is normal for some meteors. When NASA’s Don Yeomans was asked about a bright green fireball over the Southwest in 2011, he said the color likely came from nickel or magnesium in the space rock, Space.com reported. Copper is not required.
• The timing fits a busy sky. The Twinkle report itself raised the possibility that Earth was passing through a region of heavy meteor activity, and noted that 1948 was a sunspot maximum.
• Many reports were mundane. Twinkle investigators concluded that many sightings were likely airplanes, rockets, planets, clouds and especially balloons, which were common over the missile ranges.
• Expert eyewitnesses disagreed. Harvard astronomer Donald Menzel saw a green fireball near Alamogordo in 1949 and later described it as a meteor.
• Silence is not proof. A meteor’s boom can be faint, delayed or lost entirely depending on altitude, distance and terrain, so a quiet fireball is unusual but not impossible.
• Los Alamos moved on. The laboratory says on its own history pages that the national security concern was ultimately dismissed and the fireballs were likely natural.

Why It Matters

The green fireballs grip people for a simple reason. The men who saw them were not cranks. They were pilots, security officers and some of the most accomplished scientists of the 20th century, and they wrote down in classified records that they did not know what they were looking at.

The story also echoes today. Modern military reports in the PURSUE files describe glowing orbs near sensitive sites, and the government still labels most cases unresolved rather than solved. The 1949 transcript shows that “unresolved” has a long history, and that the people charged with protecting America’s nuclear arsenal took strange lights seriously, then and now.

Finally, it is a lesson in how official mysteries fade. Project Twinkle did not end with an answer. It ended when the money and the manpower ran out. That gap is exactly where legends grow, as with the 1952 Tremonton film and other cases that resurfaced this year.