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National Museum of Nuclear Science & History

Anniversaries of the Atomic Bombings

The mushroom cloud over Nagasaki
This August marks the 72nd anniversary of the bombings of Hiroshima and Nagasaki. The 509th Composite Group of the Army Air Forces flew from Tinian Island in the Pacific to deliver the bombs, nicknamed Little Boy and Fat Man. Little Boy, a uranium gun-type bomb, exploded with approximately 15 kilotons of force over Hiroshima on August 6, 1945. Fat Man, a plutonium implosion bomb, was dropped on Nagasaki three days later with an estimated yield of 20 kilotons. Japan officially surrendered on August 15. For a detailed timeline of the atomic bombing missions and the aftermath, please click here.
By the end of 1945, the bombings had killed an estimated 140,000 people at Hiroshima and 74,000 at Nagasaki, including those who died from radiation poisoning. The survivors became known as hibakusha (literally “atomic bomb-affected people”). Historians, scientists, and politicians continue to debate the decision to drop the bomb.
Colonel Paul Tibbets, the pilot of the Enola Gay which dropped the bomb on Hiroshima, remembered, “The whole sky lit up when it exploded. By the time we turned around to look at it, there was nothing but a black boiling mess hanging over the city. It was actually obscuring everything but something on the outskirts. You wouldn’t have known that the city of Hiroshima was there unless you had seen it coming in.” For more interviews with service members who flew on the atomic bomb missions, visit AHF’s “Voices of the Manhattan Project” website.
Norman Brown, a chemist and member of the Special Engineer Detachment, recalled, “Most of us at Los Alamos felt that the nuclear weapon should not be used in war first, that it should be demonstrated to the Japanese before it was used. But the powers that be decided that they were going to use this weapon.”
Others, such as physicist Leona Marshall Libby, asserted, “In wartime, it was a desperate time. I think we did right and we couldn’t have done differently. When you’re in a war to the death, I don’t think you stand around and say, ‘Is it right?’”
To read more accounts of and reflections on the bombings from Manhattan Project veterans, please see Manhattan Project Veterans on the Bombing of Hiroshima.