1. Most people died from burns. According to the health department of Hiroshima prefecture, on the day of the explosion, 60 percent of people died was because of flash or flame burn and 30 percent of people died from falling debris. After the bomb, only 15-20 percent died from radiation sickness.
2. The way American chose target. It should be larger than 5 km and was a large urban area. Attacking Tokyo has a greater fame than other target but least strategic value. Hiroshima was attracted that day is partly because it is sunny and the weather is clear in Hiroshima that day.
3. Genbaku dome. The genbaku dome left right now is only 150 m from where the bomb was. It is probably because the bomb detonated in the air and the blast was going more downward than sideways. Since the Genbaku dome is very close to the center, it survived.
4. The closest survivor was only 170 meter from the center. He is in a basement of a reinforced concrete building. Another close survivor is Akiko Takakura. She was 300 meter away from the center and was in a solidly built Bank.
5. Only 3 days after the Hiroshima nuclear attack, Nagasaki was attacked again. An air alert was sounded in 7:50 that day while cleared on 8:30. Then at 11:00, the bomb was dropped.
6. The nuclear bombs themselves cost about $2 billion dollars each.
7. Within the first several months of the bombing, about 150,000-250,000 people were killed which is about half of the people died on the first day.
8. The U.S. has planed for several more atomic attacks on Japan in September and October.
9. Even after the atomic bomb was dropped, the war council still kept its conditions for surrender.
10. There are people that have experienced both bombs and survived.