Portal:Disasters/Selected anniversary/August 2007
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The atomic bombings of Hiroshima and Nagasaki were nuclear attacks during World War II against the Empire of Japan by the United States of America under US President Harry S. Truman. On August 6, 1945, the nuclear weapon "Little Boy" was dropped on the city of Hiroshima (広島市 Hiroshima-shi?), followed on August 9, 1945 by the detonation of the "Fat Man" nuclear bomb over Nagasaki (長崎市 Nagasaki-shi?). They are the only instances of the use of nuclear weapons in warfare.
In estimating the number of deaths caused by the attacks, there are several factors that make it difficult to arrive at reliable figures: inadequacies in the records given the confusion of the times, the small number who died months or years after the bombing as a result of radiation exposure, and the pressure to either exaggerate or minimize the numbers, depending upon political agenda. That said, it is estimated that as many as 140,000 had died in Hiroshima by the bomb and its associated effects, with the estimate for Nagasaki roughly 74,000. Almost all of the casualties were a direct result of the bomb itself, with very few people dying from radiation induced illnesses. In both cities, the overwhelming majority of the deaths were those of civilians. The role of the bombings in Japan's surrender, as well as the effects and justification of them, has been subject to much debate.
Hiroshima was the primary target of the first nuclear bombing mission on August 6, with Kokura and Nagasaki being alternative targets. August 6 was chosen because there had previously been cloud over the target. The B-29 Enola Gay, piloted and commanded by 509th Composite Group commander Colonel Paul Tibbets, was launched from North Field airbase on Tinian in the West Pacific, about six hours flight time from Japan. The Enola Gay (named after Colonel Tibbets' mother) was accompanied by two other B29s, The Great Artiste which carried instrumentation, commanded by Major Charles W. Sweeney, and a then-nameless aircraft later called Necessary Evil (the photography aircraft) commanded by Captain George Marquardt.
After leaving Tinian the aircraft made their own individual way to Iwo Jima where they rendezvoused at 2440 m (8000 ft) and set course for Japan. The aircraft arrived over the target in clear visibility at 9855 m (32,000 ft). On the journey, Navy Captain William Parsons had armed the bomb, which had been left unarmed to minimize the risks during takeoff. His assistant, 2nd Lt. Morris Jeppson, removed the safety devices 30 minutes before reaching the target area.
The release at 08:15 (Hiroshima time) was uneventful, and the gravity bomb known as "Little Boy", a gun-type fission weapon with 60 kg (130 pounds) of uranium-235, took 57 seconds to fall from the aircraft to the predetermined detonation height about 600 meters (2,000 ft) above the city. The radius of total destruction was about 1.6 km (1 mile), with resulting fires across 11.4 km² (4.4 square miles). Infrastructure damage was estimated at 90 percent of Hiroshima's buildings being either damaged or completely destroyed.
About an hour before the bombing, Japanese early warning radar detected the approach of some American aircraft headed for the southern part of Japan. An alert was given and radio broadcasting stopped in many cities, among them Hiroshima. At nearly 08:00, the radar operator in Hiroshima determined that the number of planes coming in was very small—probably not more than three—and the air raid alert was lifted. To conserve fuel and aircraft, the Japanese had decided not to intercept small formations. The normal radio broadcast warning was given to the people that it might be advisable to go to air-raid shelters if B-29s were actually sighted, but no raid was expected beyond some sort of reconnaissance.
On August 15, 1945 Japan announced its surrender to the Allied Powers, signing the Instrument of Surrender on September 2 which officially ended World War II. Furthermore, the experience of bombing led post-war Japan to adopt Three Non-Nuclear Principles, which forbids Japan from nuclear armament.
