Atomic Heritage Foundation

In partnership with the National Museum of Nuclear Science & History National Museum of Nuclear Science & History

The Trinity Test

The Trinity Test

The Trinity Test mushroom cloud

The Detonation

Turret for following camera

Capturing the Trinity Test

Jack Aeby's famous color photograph of the Trinity Test

Eyewitness Accounts

A road by Trinity Site

Making Sure Nobody Noticed

Norris Bradbury with the "Gadget" on top of the Trinity test tower

A Long Night’s Vigil

J. Robert Oppenheimer's Los Alamos ID badge photo

Now I Am Become Death

  • The Detonation

    The Detonation

    Manhattan Project veterans Stanley Hall and Hans Courant describe the moment that the “Gadget” nuclear device detonated.

    Narrator: Stanley Hall and Hans Courant both served in the Special Engineer Detachment at Los Alamos. Both can summon back the exact moment that the Gadget detonated.

    Stanley Hall: That day and time when the radio comes on in the morning, they play “The Star Spangled Banner.” The radio was next to the speaker where somebody was talking to us, and then they started playing “The Star Spangled Banner” at the same time that the bomb went off.

    Hans Courant: Then the countdown began, and then the flash. My hands got warm from the heat from the bomb, which just grew and grew, and then eventually started up into the sky.

    It was terrible. It all worked, and, suddenly, I realized that next time there would be people under it. It never occurred to me. Well, it was also wonderful. It worked.

  • Capturing the Trinity Test

    Capturing the Trinity Test

    Manhattan Project photographer Berlyn Brixner recalls being stunned by the large explosion of the Trinity Test.

    Narrator: Manhattan Project photographer Berlyn Brixner remembers the critical moment surrounding the Trinity Test.

    Berlyn Brixner: Well, I was sitting at one of my cameras, motion picture cameras, which was on a panoraming device. I was just sitting there with the camera running. Everything was operated from the central control station. So I didn’t have to do anything at the time but just sit there.

    I had a loudspeaker actually and was listening to the countdown, and so I knew when the explosion was to occur. I had arranged a very dense welding glass type of glasses in front of my eyes, and I was looking directly at the Zero. I was one of the few people allowed to do that. It was perfectly safe through these welding glasses. I was looking right at it, just staring at where it was.

    Of course, it was nighttime. I couldn’t see anything. But when the explosion went off, that welding glass seemed to just glow white, just intense white like the sun. So it just blinded me, and so I looked aside to the left. The Oscura Mountains were at the left, and they were just lit up like daylight then. So I looked at that for a few seconds, and then I looked back through my welding glass and I saw that the terrific explosion had taken place. Just unbelievably large explosion.

    My camera was just sitting there, but soon the ball of fire was starting to rise and I thought, “Gee, I better get busy!” So abruptly I raised it, and photographed the ball of fire as it went up to the stratosphere. I kept photographing it for the next couple of minutes or so.

    I knew immediately that the explosion had exceeded the greatest expectations and that essentially we had won the war, because that bomb would soon be used on Japan. And it was. That was July the 16th, I believe, and the war was over only about three weeks later. 

  • Eyewitness Accounts

    Eyewitness Accounts

    ​​Manhattan Project veterans William Spindel, Roger Rasmussen, Lilli Hornig, and Val Fitch describe witnessing the Trinity Test.

    Narrator: Manhattan Project scientists William Spindel, Roger Rasmussen, Lilli Hornig, and Val Fitch remember witnessing the Trinity Test, including the vibrant colors and the force of the shockwave.

    William Spindel: I was about twenty miles away from the site. We were supposed to keep our eyes closed for the first ten seconds because of ultraviolet radiations, and then we were told that it was okay, we could watch. I estimated that at twenty miles away, the explosion travels at the speed of sound, would take about a minute to reach me.

    It was the most—not frightening, but intimidating minute I have ever spent. Seeing this terrible ball, growing and growing, enormous colors. What was the blast going to be when it finally got to me a minute later? Hugging the ground in fear. Fortunately, obviously, it wasn’t that great, because I’m still here.

    Roger Rasmussen: The brightest light that I had ever observed with my eyes closed, that I’d ever seen. That was the detonation. But no noise and no sound. Nothing to see, until our troop master said we could look up. The lightning had passed by then, but there was this beautiful color of the bomb. Gorgeous.

    Lilli Hornig: This thing bloomed in front of us. Boiling clouds and color. Vivid colors like violet, purple, orange, yellow, red, just everything. It was fantastic. And we were all kind of shaken up.

    Val Fitch: It’s the most surprising thing of all, that fantastic flash of light. Then of course you see the dust cloud and the ball, slowly rising off the ground and the famous mushroom cloud eventually. I got up off the ground to get a better view of that, totally forgetting that the shockwave had yet to arrive. It might take only thirty microseconds for the light to arrive, but it takes about thirty seconds for the shockwave. It was hard to overstate the impact on the senses. Words haven’t been invented to describe it.

  • Making Sure Nobody Noticed

    Making Sure Nobody Noticed

    Manhattan Project counterintelligence officer Thomas O. Jones recalls his job to make sure that the Trinity Test remained secret, no matter what happened. Chemist Lilli Hornig remembers meeting some people who wondered what had caused the nearby explosion.

    Narrator: The Trinity Site was quite isolated. Still, Manhattan Project leaders were concerned that the Test would be impossible to hide from surrounding communities. Thomas O. Jones served as the intelligence officer at Los Alamos.

    Thomas Jones: My role in that situation was to see whether this bomb went “pfump” or whether it took half of the state of New Mexico into the air and perhaps into flights around the world. No one knew that wasn’t my job, my job was to see that whatever happened, no one noticed.

    Narrator: Manhattan Project chemist Lilli Hornig witnessed the Trinity Test from Sandia Mountain. She and her group of friends were not the only ones who heard the explosion.

    Lilli Hornig: And then we backed up and started down the mountain, and we stopped at a diner somewhere near Albuquerque for breakfast. And the guy behind the counter said, “You guys know anything about that explosion they had down at the proving grounds?” We said, “What, no, we didn’t know about that!”

  • A Long Night’s Vigil

    A Long Night's Vigil

    Elsie McMillan vividly describes waiting with her neighbor Lois Bradbury for word that the Trinity Test had been a success.

    Narrator: Elsie McMillan remembers waiting up all night to see a glimpse of the test with her neighbor Lois Bradbury. Lois’ husband Norris Bradbury was in charge of the final assembly of the “Gadget,” or plutonium test bomb.

    Elsie McMillan: There was a light tap on my door. There stood Lois Bradbury, my friend and neighbor. She knew. Her husband was out there, too. She said her children were asleep, and would be all right since she was so close and could check on them every so often.

    “Please, can’t we stay together this long night?” she said. We talked of many things, of our men, whom we love so much, of the children, their futures, of the war with all its horrors. We kept the radio going softly, despite the fact our last word had been that the test would probably be at 5:00 a.m. We dared not turn it off.

    Suddenly, there was a flash and the whole sky lighted up. The time was 5:32 a.m. The baby didn’t notice. We were too fearful and awed to speak.

    The news came. “Flash! The explosive dump at the Alamogordo airfield has exploded. No lives are lost. This explosion is what caused the tremendous sound and the light in the sky.”

    We looked at each other. It was a success. Could we believe the announcement, no lives are lost? They had not said no injuries. We had hours to wait to be absolutely sure. At least it was over with.

    Lois went home to grab a few hours of rest before her family might awaken. I, too, crawled into bed, but found I could not sleep. The day dragged on. I tried walking the mesa with the children, but by lunchtime home was where I wanted to be.

    The door opened about 6:00 o’clock in the evening. We were in each other’s arms. Then, and only then, did the tears come streaming down my face.

  • Now I Am Become Death

    Now I Am Become Death

    Los Alamos laboratory director J. Robert Oppenheimer describes his response to the Trinity Test.

    Narrator: J. Robert Oppenheimer recalls how and he and other felt in the moments following the Trinity Test.

    J. Robert Oppenheimer: We knew the world would not be the same. Few people laughed, few people cried, most people were silent. I remembered the line from in the Hindu scripture, the Bhagavad-Gita. Vishnu is trying to persuade the prince that he should do his duty, and to impress him takes on this multi-armed form and says, “Now I am become death, the destroyer of worlds.” I suppose we all thought that, one way or another.


Quick Fact:
At 5:29 AM, the "Gadget" nuclear device detonated at the top of the 100-foot steel tower. The device yielded between 15 and 20 kilotons of force, slightly more than the Little Boy bomb dropped on Hiroshima. The Atomic Age had begun.