The bomber, piloted by the commander of the 509th Composite Group, Colonel Paul Tibbets, flew at low altitude on automatic pilot before climbing to 31,000 feet as it neared the target area. At approximately 8:15 a.m. Hiroshima time the Enola Gay released \"Little Boy,\" its 9,700-pound uranium gun-type bomb, over the city. Tibbets immediately dove away to avoid the anticipated shock wave. Forty-three seconds later, a huge explosion lit the morning sky as Little Boy detonated 1,900 feet above the city, directly over a parade field where soldiers of the Japanese Second Army were doing calisthenics. Though already eleven and a half miles away, the Enola Gay was rocked by the blast. At first, Tibbets thought he was taking flak. After a second shock wave (reflected from the ground) hit the plane, the crew looked back at Hiroshima. \"The city was hidden by that awful cloud . . . boiling up, mushrooming, terrible and incredibly tall,\" Tibbets recalled. The yield of the explosion was later estimated at 15 kilotons (the equivalent of 15,000 tons of TNT).
Portions of the text for this page were adapted from, and portions were taken directly from the Office of History and Heritage Resources publication: F. G. Gosling, The Manhattan Project: Making the Atomic Bomb (DOE/MA-0001; Washington: History Division, Department of Energy, January 1999), 51-53. Also used was the report on \"The Atomic Bombings of Hiroshima and Nagasaki\" in the official Manhattan District History, produced by the War Department in 1947 at the direction of Leslie Groves, especially pages 1-19; the \"Atomic Bombings\" document is available in the University Publications of America microfilm collection, Manhattan Project: Official History and Documents (Washington: 1977), reel #1/12; the report itself is a government document. Tibbets's description is from Paul W. Tibbets, \"How to Drop an Atom Bomb,\" Saturday Evening Post 218 (June 8, 1946), 136. The estimate of Little Boy's yield is from United States Nuclear Tests, July 1945 through September 1992 (DOE/NV-209-REV 15; Las Vegas, NV: Nevada Operations Office, Department of Energy, December 2000), vii. Summaries of Hiroshima and Nagasaki casualty rates and damage estimates appear in Leslie R. Groves, Now It Can Be Told (New York: Harper & Row, 1962), 319, 329-330, 346, and Vincent C. Jones, Manhattan: The Army and the Atomic Bomb, United States Army in World War II (Washington: Center of Military History, United States Army, 1988), 545-548. A translation of the leaflets dropped on Japan in between Hiroshima and Nagasaki can be found in Dennis Merrill, ed., Documentary History of the Truman Volume 1, The Decision to Drop the Atomic Bomb on Japan (Bethesda, MD: University Publications of America, 1995), 194-195. The photograph of the mushroom cloud is courtesy the United States Air Force (USAF) (via the National Archives (NARA)). The photographs of Little Boy and Fat Man are courtesy the U.S. Army Corps of Engineers (via NARA). The photograph of the Enola Gay landing at Tinian Island is courtesy the USAF. The photograph of the woman with burns on her back is courtesy the U.S. Army Corps of Engineers (via NARA). The photographs of the mushroom cloud taken from the ground and of the debris (including the Hiroshima Peace Memorial (Genbaku \"A-bomb\" Dome) are courtesy the Federation of American Scientists. The photographs of the hospital and of the lone soldier walking through an almost-completely leveled portion of the city are courtesy the Department of the Navy (via NARA); the former was taken by Wayne Miller. 1e1e36bf2d