August 6, 1945: The Bombing of Hiroshima

Tomorrow marks a notable anniversary. Shamelessly stolen from myself, from a few years ago…

Just a few weeks after the first atomic bomb was detonated by the Manhattan Project in the desert Southwest (on July 16, 1945) the US Army Air Force dropped an atomic bomb, code named “Little Boy” on the city of Hiroshima, Japan. Manhattan Project: The Atomic Bombing of Hiroshima, August 6, 1945

At 8:15 in the morning local time, a 15 kiloton uranium gun-trigger bomb was dropped on a city of 300,000 people.

The blast wave filled the air with broken glass. The flash from the detonation burned the shadows of people onto the walls left standing. 9 out of 10 people within half a mile of ground zero were dead.

The photo above is of the city center some weeks after the bombing. Click for a larger image.

In those areas most seriously affected virtually no one escaped serious injury. The numerous small fires that erupted simultaneously all around the city soon merged into one large firestorm, creating extremely strong winds that blew towards the center of the fire. The firestorm eventually engulfed 4.4 square miles of the city, killing anyone who had not escaped in the first minutes after the attack.

Those farther away had other problems as they thought their buildings had been bombed. Make-shift rescue parties started working shortly after the blast. Outside relief was slow to arrive, because the Japanese high command didn’t understand what happened. They couldn’t imagine destruction on that scale. It wasn’t until the US announcement 16 hours later that the true nature of what happened came to light.

While some things started to get back to normal in a few days, the effects of radiation sickness started to show itself.

Power in undamaged areas of the city was even restored on August 7th, with limited rail service resuming the following day. Several days after the blast, however, medical staff began to recognize the first symptoms of radiation sickness among the survivors. Soon the death rate actually began to climb again as patients who had appeared to be recovering began suffering from this strange new illness. Deaths from radiation sickness did not peak until three to four weeks after the attacks and did not taper off until seven to eight weeks after the attack.

The effects of radiation poisoning are truly hideous. A high enough exposure and you are dead – you are just waiting for the mechanics of dying to be complete. You can find descriptions of the gruesome details elsewhere. All I will say here is that I would not want to wait around for that end.

75 Years of the Nuclear Age

The GadgetJuly 16, 1945. 5:29 AM Mountain Time, near Alamogordo, New Mexico.

The Gadget was detonated – the 1st nuclear explosion – by the Manhattan Project. It was a plutonium implosion device.

At 05:29:21 (July 16, 1945) local time, the device exploded. It left a crater of radioactive glass in the desert 10 feet (3.0 m) deep and 1,100 feet (340 m) wide. At the time of detonation, the surrounding mountains were illuminated brighter than daytime for one to two seconds, and the heat was reported as being as hot as an oven at the base camp. The observed colors of the illumination ranged from purple to green and eventually to white. The roar of the shock wave took 40 seconds to reach the observers. The shock wave was felt over 100 miles (160 km) away, and the mushroom cloud reached 7.5 miles (12.1 km) in height. After the initial euphoria of witnessing the explosion had passed, test director Kenneth Bainbridge commented to Los Alamos director J. Robert Oppenheimer, Now we are all sons of bitches. Oppenheimer later stated that, while watching the test, he was reminded of a line from the Bhagavad Gita, a Hindu scripture: Now I am become Death, the destroyer of worlds.

(The Gadget was similar to Fat Man, which was dropped on Nagasaki on the 9th August that year. Little Boy, which was dropped on Hiroshima on August 6th, was a uranium gun-trigger.)

Video of the blast is all over YouTube. Here is a short one.

The best documentary I have seen on The Manhattan Project is The Day After Trinity. It is currently available on YouTube; how long that will be the case is anyone’s guess. When it was filmed, several of the scientists from The Manhattan Project were still alive for interviews.

It was later determined to be an 18-to-20 kiloton explosion. (The equivalent of 18,000 tons of TNT or more) Relatively small by modern standards. Thermonuclear – or hydrogen – bombs are measured in megatons. (The largest -Tsar Bomba of the USSR – measured 50 megatons)

The Gadget Detonation at Trinity: Dawn of the Nuclear Age on July 16, 1945

The GadgetJuly 16, 1945. 5:29 AM Mountain Time, near  Alamogordo, New Mexico.

The Gadget was detonated – the 1st nuclear explosion – by the Manhattan Project. It was a plutonium implosion device.

At 05:29:21 (July 16, 1945) local time, the device exploded. It left a crater of radioactive glass in the desert 10 feet (3.0 m) deep and 1,100 feet (340 m) wide. At the time of detonation, the surrounding mountains were illuminated brighter than daytime for one to two seconds, and the heat was reported as being as hot as an oven at the base camp. The observed colors of the illumination ranged from purple to green and eventually to white. The roar of the shock wave took 40 seconds to reach the observers. The shock wave was felt over 100 miles (160 km) away, and the mushroom cloud reached 7.5 miles (12.1 km) in height. After the initial euphoria of witnessing the explosion had passed, test director Kenneth Bainbridge commented to Los Alamos director J. Robert Oppenheimer, Now we are all sons of bitches. Oppenheimer later stated that, while watching the test, he was reminded of a line from the Bhagavad Gita, a Hindu scripture: Now I am become Death, the destroyer of worlds.

(The Gadget was similar to Fat Man, which was dropped on Nagasaki on the 9th August that year. Little Boy, which was dropped on Hiroshima on August 6th, was a uranium gun-trigger.)

Video of the blast is all over YouTube. Here is a short one.

The best documentary I have seen on The Manhattan Project is The Day After Trinity. It doesn’t seem to be anywhere for streaming.

It was later determined to be an 18-to-20 kiloton explosion. (The equivalent of 18,000 tons of TNT or more) Relatively small by modern standards. Thermonuclear – or hydrogen – bombs are measured in megatons. (The largest -Tsar Bomba of the USSR – measured 50 megatons)