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Edward Teller and the Green Fireballs: Mysterious Lights over the City of the Atomic Bomb

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In December 1948, bright green orbs began streaking across the skies of New Mexico, right where the United States' most secret nuclear weapons research was taking place. Pilots swerved to avoid them, Edward Teller took part in the conference at Los Alamos, and the Air Force built an observation network. No solution was ever found, however. This year, a newly released letter has brought the case back into the spotlight.

When: December 1948
Where: United States
Witnesses: Military personnel, scientists, civilians

In May 2026, the United States government released another batch of its files on unidentified anomalous phenomena. Among the documents is a handwritten letter dated 1970, in which a Los Alamos scientist reports that between 1948 and 1951 he regularly saw green lights over the mountains, in the evenings between nine and eleven o'clock, once moving in some kind of formation.

The letter leads back to a mystery more than seventy years old: the case of the green fireballs, which occupied the US military and scientists at the highest level at the dawn of the Cold War.

The night they saw eight

In late November 1948, strange reports came in from the Albuquerque area: a green streak crossed the sky low on the horizon. Intelligence officers at nearby Kirtland Air Force Base first suspected flares, but the reports became more and more detailed, and the objects seemed to be getting larger and larger.

The turning point was December 5, 1948. At 9:27 p.m., the crew of an Air Force C-47 transport plane flying at 5,500 meters east of Albuquerque saw a bright green fireball. Barely 20 minutes earlier, they had already spotted a similar one. Eight minutes later, the pilots of Pioneer Airlines Flight 63 observed an object near Las Vegas, New Mexico, that was first orange-red, then turned green, and was heading straight toward them head-on. The captain turned the plane sharply to avoid it. According to the pilots, the orb was as large as the full moon, or larger.

Edward J. Ruppelt, who later headed the Air Force's UFO investigation, Project Blue Book, counted a total of eight separate fireballs that night. Three days later, two Kirtland officers also saw one from their aircraft: the green orb sped past roughly 600 meters above them, on an almost horizontal path, and was visible for two seconds.

The meteor expert who wasn't convinced by meteors

The natural expert on the matter was Lincoln LaPaz, head of the University of New Mexico's Institute of Meteoritics. LaPaz had previously successfully calculated the impact sites of several meteorites. This time, together with the Kirtland officers, he interviewed the witnesses, plotted the trajectory of the December 5 fireball, and combed the presumed impact area in northern New Mexico, all the way to the Texas border. They found nothing.

It was then that LaPaz began to doubt that these were meteors. He later listed five arguments:

the color was a vivid, brilliant green, not the pale green known from meteors;
the trajectory was flatter than a meteor's;
according to the witnesses, the orbs were huge and blinding;
there was no sound and no shock wave, even though large meteors can break windows and frighten animals;
not a single fragment was ever found.

The fireballs appeared almost every night in December and January. And not just anywhere: Los Alamos, the Sandia base and Kirtland Air Force Base were key sites of the US nuclear weapons program at the time. Similar phenomena were also reported near the Hanford and Oak Ridge nuclear facilities.

Conference with Edward Teller

On February 16, 1949, the Los Alamos laboratory held a two-day conference. Participants included atmospheric physicist Joseph Kaplan, Hungarian-born Edward Teller, the "father of the hydrogen bomb," and LaPaz, as well as military officers and representatives of the FBI and the Atomic Energy Commission. According to Ruppelt, almost everyone sitting in the room had already seen a green fireball.

Opinions were divided. Some pointed out that greenish meteors had been observed before, and that the flat trajectory could simply be an illusion caused by the viewing angle. LaPaz maintained that the phenomenon was not natural. According to a summary in the laboratory's archives, the participants did not consider the fireballs a serious national security threat, but they found no solution.

The camera that was always too late

The conference led to the launch of Project Twinkle. The plan was to set up three observation stations around White Sands with special film cameras that would record the time, direction and altitude along with the image. From this, the fireballs' speed, altitude and size could have been calculated.

However, the project never operated at full strength. The budget was tight, only one camera was available, and it was always taken to wherever a report had just come in, but always too late. Ruppelt remarked sarcastically that a duck hunter doesn't run around the swamp either, but waits in a good spot. Project Twinkle never photographed a single green fireball. After about two years, with the outbreak of the Korean War, it was quietly shut down with the official conclusion that the phenomenon was probably of natural origin.

How did the story live on?

In 1951, Ruppelt himself traveled to Los Alamos. Over lunch, scientists and technicians talked to him about the fireballs for hours. A private pilot described one as if a softball painted with fluorescent paint had been thrown in his face. Some of the group thought they might be unmanned experimental devices launched from hundreds of kilometers up. Ruppelt did not take a position, but he noted that by then there had been no "real" green fireball report for a year and a half, and the later ones were ordinary greenish meteors.

LaPaz never said what he thought the orbs were, only that he did not believe they were natural. He hoped that one day one of them would reach the ground and the mystery would be solved. That did not happen. When, in September 1954, a blindingly green fireball the size of the full moon crossed over Colorado and New Mexico and flooded the phone lines of police and newsrooms, LaPaz said he did not expect anything to be found.

Since then, the green fireballs have been a fixture of Cold War UFO history. The 1970 letter released this year adds another witness account to this story, albeit one written down almost twenty years after the events.

The sober take

The green fireballs were most likely extremely bright meteors, so-called bolides. The investigation at the time reached this conclusion as well, and our current knowledge also supports it. Most of LaPaz's arguments can be readily explained today:

The green color: this is particularly common with bright fireballs. Excited oxygen in the atmosphere and metals in the meteor, such as nickel and magnesium, can produce a vivid green light.
Silent, and no remains: fireballs burn up at altitudes of 70–120 kilometers. The sound, if it reaches the ground at all, arrives only minutes later. Most meteors burn up completely, leaving no meteorite.
Flat trajectory, an orb that seems close: the path and distance of a distant object traveling at high altitude are almost impossible to estimate by eye, especially from an aircraft. The "full-moon-sized" description actually reflects the brightness, not the actual size. We wrote more about how much our eyes deceive us in such cases in our article on fireballs.
Why there and then? In the winter of 1948–49, the weather over New Mexico was clear, and an especially large number of trained, alert observers worked around the nuclear facilities, reporting every unusual phenomenon. The many reports thus also partly reflect where people were watching most closely.

The solution, however, is not complete: since Project Twinkle never captured a single image, there is no measurement of the fireballs of that time that would settle the debate for good. And the lights described in the 1970 letter, seen regularly in the evening between nine and eleven and once moving in formation, do not necessarily belong to the same phenomenon. It is impossible to determine what they were from this brief description.

What was that?

A fireball in the sky? A bright meteor or reentering space debris