Trinity Test -1945

Trinity Test -1945

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The famous photo of the Trinity test, taken by Jack Aeby.

The Alamogordo Bombing and Gunnery Range, 230 miles south of Los Alamos, is most famous for its landmark role as the birthplace of nuclear weapons.

On July 16, 1945, Gadget, an implosion plutonium bomb, the same style as the one used at Nagasaki, detonated with 20 kilotons of force, slightly more than the Little Boy bomb dropped on Hiroshima.  Originally the test was to occur at 4 a.m., but it was delayed to 5:30 after an early morning thunderstorm. At 5:29:45, Gadget exploded and the Atomic Age began.

For rare photographs taken by Marvin Davis, an MP stationed at the Trinity site, click here. For videos of the Trinity test, visit our YouTube channel.


Eyewitness Accounts

Witnesses had a variety of reactions to the Trinity test, ranging from joy to amazement to horror. 



Many of those present commented on the terrifying beauty of the blast:

  • Brigadier General Thomas F. Farrell: "The whole country was lighted by a searing light with the intensity many times that of the midday sun. It was golden, purple, violet, gray and blue. It lighted every peak, crevasse and ridge of the nearby mountain range with a clarity and beauty that cannot be described but must be seen to be imagined. It was that beauty the great poets dream about but describe most poorly and inadequately."
  • Kenneth Bainbridge: "No one who saw it could forget it, a foul and awesome display."
  • Joan Hinton: "It was like being at the bottom of an ocean of light. We were bathed in it from all directions. The light withdrew into the bomb as if the bomb sucked it up. Then it turned purple and blue and went up and up and up. We were still talking in whispers when the cloud reached the level where it was struck by the rising sunlight so it cleared out the natural clouds. We saw a cloud that was dark and red at the bottom and daylight at the top. Then suddenly the sound reached us. It was very sharp and rumbled and all the mountains were rumbling with it."
  • Frank Oppenheimer: "And so there was this sense of this ominous cloud hanging over us. It was so brilliant purple, with all the radioactive glowing. And it just seemed to hang there forever. Of course it didn’t. It must have been just a very short time until it went up. It was very terrifying. And the thunder from the blast. It bounced on the rocks, and then it went—I don’t know where else it bounced. But it never seemed to stop."
  • Robert Serber: "The grandeur and magnitude of the phenomenon were completely breath-taking."



Some were awed by the implications of their work:

  • The GadgetEdwin M. McMillan: "The whole spectacle was so tremendous and one might almost say fantastic that the immediate reaction of the watchers was one of awe rather than excitement… I am sure that all who witnessed this test went away with a profound feeling that they had seen one of the great events of history."
  • Isidor I. Rabi: "It was seen to last forever. You would wish it would stop; altogether it lasted about two seconds. Finally it was over, diminishing, and we looked toward the place where the bomb had been; there was an enormous ball of fire which grew and grew and it rolled as it grew; it went up into the air, in yellow flashes and into scarlet and green. It looked menacing… A new thing had just been born; a new control; a new understanding of man, which man had acquired over nature."
  • J. Robert Oppenheimer: "We knew the world would not be the same. A few people laughed, a few people cried, most people were silent. I remembered the line from 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 his multi-armed form and says, ‘Now, I am become Death, the destroyer of worlds.’ I suppose we all felt that one way or another."



Others felt relieved that their years of working on the Manhattan Project had resulted in success:

  • Trinity explosionKenneth Griesen: "Between the appearance of light and the arrival of the sound, there was loud cheering in the group around us. After thenoise was over, we all went about congratulating each other and shaking hands. I believe we were all much more shaken up by the shot mentally than physically."
  • Cyril S. Smith: "At the instant after the shot, my reactions were compounded of relief that ‘it worked’; consciousness of extreme silence, and a momentary question as to whether we had done more than we intended. Practically none of the watchers made any vocal comment until after the shock wave had passed and even then the cheers were not intense or prolonged."
  • General Leslie R. Groves: "Drs. Conant and Bush and myself were struck by an even stronger feeling that the faith of those who had been responsible for the initiation and the carrying on of this Herculean project had been justified. I personally thought of Blondin crossing Niagara Falls on his tight rope, only to me this tight rope had lasted for almost three years and of my repeated confident-appearing assurances that such a thing was possible and that we would do it."
  • In the words of author Joseph Kanon in his novel Los Alamos: "This was the real secret. Annihilation. Nothing else. A chemical pulse that dissolved finally in violet light. No stories. Now we would always be frightened."



News of the success of the Trinity test was initially limited to those Manhattan Project scientists who already had knowledge of the atomic bomb, despite the fact that the explosion was felt in cities throughout the state. Officially, the cause was reported as the accidental detonation of a bunker containing a number of high explosives and pyrotechnics. Only after the atomic bombings of Japan was Trinity's true nature made known.

The explosion annihilated nearly all of the 100-foot metal tower from which the bomb was dropped and created a crater of a radioactive green glassy substance known as trinitite, which is today prized as a collector's item. Radiation levels at the site remain about 10 times as high as natural background radiation. After being closed to the public for many years, the Trinity site was declared a National Historic Landmark district in 1965 and was listed on the National Register of Historic Places in 1966. It is now open to visitors on the first Saturdays of April and October.


Related Video: 

Trinity Test Color Footage

Color video of the Trinity test explosion.