Nagasaki Atomic Bomb Museum
The atomic bomb was developed by scientists working under the Manhattan Project. The project was granted funding on December 6, 1941, with American leaders aiming for a new invention that would serve as a wartime weapon. The decision to drop an atomic bomb on Japan had been made by 1943, and a shortlist of candidate target cities was in place in 1945. At the time, it was argued that an atomic bombing would bring about a more rapid end to the war. Hiroshima, the first target, was selected to show the power of America's new weapon. The second bombing, of Nagasaki, was intended to demonstrate that the USA had a large arsenal. At 11:02 A.M. local time on August 9, 1945, the atomic bomb, nicknamed Fat Man as its code name by Robert Serber in the United States (after Sydney Greenstreet's character in "The Maltese Falcon") was dropped on Nagasaki, forever changing the city's landscape. A mushroom cloud rose to an altitude of 45,000 feet above the city.
Nuclear weapon yield
Where these data are not available, as in a number of cases, precise yields have been in dispute, especially when they are tied to questions of politics. The weapons used in the atomic bombings of Hiroshima and Nagasaki, for example, were highly individual and very idiosyncratic designs, and gauging their yield retrospectively has been quite difficult. The Hiroshima bomb, "Little Boy", is estimated to have been between (a 20% margin of error), while the Nagasaki bomb, "Fat Man", is estimated to be between (a 10% margin of error). Such apparently small changes in values can be important when trying to use the data from these bombings as reflective of how other bombs would behave in combat, and also result in differing assessments of how many "Hiroshima bombs" other weapons are equivalent to (for example, the Ivy Mike hydrogen bomb was equivalent to either 867 or 578 Hiroshima weapons — a rhetorically quite substantial difference — depending on whether one uses the high or low figure for the calculation). Other disputed yields have included the massive Tsar Bomba, whose yield was claimed between being "only" or at a maximum of by differing political figures, either as a way for hyping the power of the bomb or as an attempt to undercut it.