10 Explosive Facts About the Trinity Nuclear Test

“Now I am become death, the destroyer of worlds.” That paraphrased line from the Bhagavad Gita crossed Robert Oppenheimer’s mind as he became a witness to history. On July 16, 1945, the first atomic bomb was detonated near Socorro, New Mexico—and 80 years later, we’re still feeling the political and scientific shockwaves of this high-stakes experiment. Here are the facts about the blast code-named “Trinity.”

1. Eight different sites were considered for the test.
2. Nobody knows where the code name Trinity came from.
3. There was a rehearsal.
4. Physicist Edward Teller feared the test might ignite Earth’s atmosphere.
5. Scientists made bets on how big the explosion would be.
6. The Trinity fireball was seen 180 miles away.
7. At first, civilians were told that it was an ammunition accident.
8. The Trinity bomb was the same design as Fat Man, the one that destroyed Nagasaki.
9. The nuclear test created a new substance called Trinitite.
10. A house just two miles from the blast site remained intact—and you can visit it.

Eight different sites were considered for the test.

U.S. military officials started looking for a suitable location for the Trinity test in May 1944. Barrier sand reefs in south Texas were assessed, as was an island off California’s southern coast and Rice, California (now a ghost town). Colorado's San Luis Valley region was also under consideration. 

New Mexico alone presented four separate options: the Tularosa Basin, an area near the village of near Cuba, the desert south of Grants, and a waterless desert called Jornada del Muerto, or “route of the dead men.” The latter was chosen for its wide-open and mostly uninhabited space, as well as its proximity to Los Alamos, where the Manhattan Project’s bombs were under development. Construction of the site started in fall 1944.

Nobody knows where the code name Trinity came from.

Oppenheimer took the credit, but forgot his source of inspiration. “Why I chose this name is not clear,” he said in a 1962 conversation with General Leslie Groves. The well-read physicist said that as the day of the detonation approached, he often thought of John Donne, the 17th-century poet whom he greatly admired. Donne began one famous sonnet with “Batter my heart, three person’d God,” referring to Christianity’s holy trinity. But, Oppenheimer said, “beyond this, I have no clues whatsoever.”

There was a rehearsal.

One hundred-and-eight tons of TNT were placed on a 20-foot-tall wooden platform and blown up on May 7, 1945. The run-through allowed everyone to calibrate their data collection equipment.     

Physicist Edward Teller feared the test might ignite Earth’s atmosphere.

Work came to a halt (by some accounts) when Teller presented his doomsday scenario. Fission explosions, like the one America’s first nuclear test would create, generate heat in the tens of millions of degrees. He cautioned that this heat could fuse nitrogen atoms throughout our planet’s atmosphere, kicking off a catastrophic release of energy and incinerating life on Earth. Luckily, further analysis and modeling indicated this result was unlikely.

Scientists made bets on how big the explosion would be.

Teller wagered that it would equal 45,000 tons of TNT. Hans Bethe went with 8000 tons. Oppenheimer predicted a meager 300 tons and privately bet another associate $10 that the test would fail. Leslie Groves started getting annoyed when Enrico Fermi took bets on whether the bomb would obliterate the whole world or merely New Mexico.

The Trinity fireball was seen 180 miles away.

When it detonated, the bomb wielded enough force to match around 20,000 tons of TNT. It also let loose a radiant burst of light that startled people in Albuquerque, Santa Fe, Silver City, and El Paso. 

Rowena Baca of San Antonio, New Mexico, 35 miles away, was shoved under a bed by her grandmother, who mistook the Trinity test for armageddon. Navy pilot John R. Lugo initially thought he was watching the sun rise—from the south—while flying near Albuquerque that morning,.

At first, civilians were told that it was an ammunition accident.

In response to questions from the public, the military released a statement obfuscating the true source of the explosion:

“Several inquiries have been received concerning a heavy explosion which occurred on the Alamogordo Army Air Base reservation this morning. A remotely located ammunition magazine containing a considerable amount of high explosive and pyrotechnics exploded. There was no loss of life or injury to anyone, and the property damage outside of the explosives magazine itself was negligible. Weather conditions affecting the content of gas shells exploded by the blast may make it desirable for the Army to evacuate temporarily a few civilians from their homes.”

Americans would not know what really happened until after the atomic bombs were dropped on Hiroshima and Nagasaki, Japan, the following month.

The Trinity bomb was the same design as Fat Man, the one that destroyed Nagasaki.

The military dropped a uranium-based atomic bomb, nicknamed Little Boy, on Hiroshima on August 6, 1945. Three days later, the U.S. dropped a plutonium-based bomb, Fat Man,” on Nagasaki. The former was relatively simple and Manhattan Project scientists were confident it didn’t need testing, but the latter was more complicated—it required that a core filled with plutonium implode before it could explode. 

The nuclear test created a new substance called Trinitite.

New Mexico’s sandy soil was transformed by the unnatural heat of the Trinity test into greenish-gray, glass-like minerals called Trinitite. For a few years after the test, rock hunters visited the site and collected the radioactive chunks. The military excavated and buried the remaining Trinitite at the test site in the 1950s.

A house just two miles from the blast site remained intact—and you can visit it.

Most of its windows were shattered, some shingles flew off, and the roof bowed inward, but the George McDonald ranch house remained more or less intact despite standing only two miles away from Trinity’s ground zero. Abandoned by its owners when it was appropriated by the military in 1942, the building became a workshop for Manhattan Project personnel who repurposed a bedroom as a bomb assembly zone. Since then, it’s been renovated and visitors are allowed to explore the site one day per year. 

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A version of this story was published in 2015; it has been updated for 2025.