Startling Facts About the Atomic Bombings of Hiroshima and Nagaski

Startling Facts About the Atomic Bombings of Hiroshima and Nagaski
Stanley Troutman/Pool Photo via AP
Startling Facts About the Atomic Bombings of Hiroshima and Nagaski
Stanley Troutman/Pool Photo via AP
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Seventy-four years ago this week, the United States dropped two atomic bombs on the Japanese cities of Hiroshima and Nagasaki, killing up to 226,000 people and leaving thousands more horribly disfigured by burns and radiation sickness. An estimated 2,000 more people would be diagnosed with radiation-linked cancer over the ensuing decades. The bombings and their terrifying effects forced Japan's surrender, effectively bringing World War II to a close.

A debate over whether or not the U.S. should have dropped those bombs persists to this day, but regardless of one's position in that discussion, we can all hope that these weapons will never be used again.

Here are five startling or surprising facts about the atomic bombings of Hiroshima and Nagasaki:

At the time this photo was made, smoke billowed 20,000 feet above Hiroshima while smoke from the burst of the first atomic bomb had spread over 10,000 feet on the target at the base of the rising column.

1. The destruction was sudden and swift. The atomic bombs dropped over Hiroshima and Nagasaki respectively released the energy equivalent to 15,000 and 20,000 tons of TNT. Almost all of that energy was released in the initial thirty seconds after detonation: 35% in the form of heat and light, 50% in a pressure shock wave, and 5% in nuclear radiation. The shock waves leveled almost all structures within a one mile radius from the bombs' detonation. People within 500 meters were instantly incinerated.

2. Many people suffocated. The immense explosions extended out about one mile, swiftly consuming oxygen in the blast areas, leaving little of the precious element left for living things to breathe. The ensuing firestorms that engulfed many more miles of each city ate up even more oxygen. Hundreds, perhaps thousands, suffocated.

3. Waterways evaporated. The Hiroshima fireball was 1,200 feet in diameter, with a surface temperature of 10,800 degrees Fahrenheit (6,000 Celsius). The intense heat evaporated large volumes of water in the city, "sucked up as if by a tornado," scientist Shizuyo Sutou wrote.

4. Radioactive "black rain" fell. Water vapor rose into the sky and cooled, precipitating around soot and other debris. Radioactive rain started falling roughly thirty minutes after detonation and lasted for a few hours. The downpour extended over a large area roughly 11 x 19 kilometers. "The possibility exists that the black rain included the most fallout, two-thirds of the nuclear radiation energy," Sutou said, although a 2014 study found no apparent long-term health effects from black rain exposure.

Formation of black rain from the mushroom cloud (left), and black rain areas (right)

5. Low levels of radiation may have been beneficial.  Intense levels of radiation close to the blasts killed thousands in the minutes, days, weeks, months, and years after the explosion. However, an analysis published late last year which followed 120,000 survivors of the atomic bombings showed that those "exposed to between 0.005 and 0.5 Grays of radiation (just before where light radiation sickness starts) had lower relative mortality than control subjects not exposed to atomic bomb radiation." This is in line with the hormetic theory of radiation, which suggests that low levels are actually good for health.

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