What Was Little Boy?

Mary McMahon
Mary McMahon

Little Boy was an atomic weapon which was detonated over the Japanese city of Hiroshima on August Sixth, 1945, marking the first time a nuclear weapon was used in wartime. The bombing of Hiroshima was followed three days later by the bombing of Nagasaki, which led the Japanese to surrender, ending the conflict of the Second World War. The bombings of Hiroshima and Nagasaki have become extremely controversial in retrospect, as some people believe that they were unnecessary, while others believe that the bombings were justified.

The atom bomb radically changed the face of warfare.
The atom bomb radically changed the face of warfare.

Like Fat Man, the bomb dropped on Nagasaki, Little Boy was developed through the offices of the Manhattan Project, a top-secret project in the Second World War which was dedicated to finding the secret of the atom bomb before the Germans did. Little Boy was a uranium bomb, the first of its kind, and the detonation of Little Boy was the second man-made nuclear explosion in history.

The detonation of Little Boy was the second man-made nuclear explosion in history.
The detonation of Little Boy was the second man-made nuclear explosion in history.

The bomb was dropped from the Enola Gay, a B-29 Superfortress named after the pilot's mother. At 1,980 feet (580 meters), the bomb detonated, using a gun-type detonation system which basically shot a uranium rod onto a spike to trigger a nuclear reaction. Within seconds, a cloud of superheated gases had formed over the city, followed by an intense pressure wave.

Little Boy was actually somewhat weaker bomb than Fat Man, with an estimated force of around 15 kilotons of TNT, but it was far more devastating, thanks to the fact that Hiroshima was on a relatively flat plain, allowing the explosion to disperse widely. An estimated 66,000 people died as an immediate result of the explosion; many of them were so completely incinerated that the only signs of their presence were eerie shadows on buildings and roadways.

In the weeks and months following, many more victims of the bomb died as a result of injuries sustained in the explosion and subsequent fires. Survivors of the bomb also experienced a variety of health problems as a result of their exposure to the radiation caused by the bomb, with around 60,000 people dying as a result of the bomb in the decades following.

The use of nuclear weapons in wartime was unprecedented before Little Boy exploded over Hiroshima on that August morning, and almost immediately, it triggered a global discussion. As follow-up studies on the long-term effects of the bomb continued, many critics became much more outspoken, including critics drawn from the ranks of the scientists who built the bomb. Some people felt that such weapons were so devastating that they should never be used in wartime again, while others felt that nuclear weapons had a legitimate place in military arsenals.

Whether or not one agrees that the atom bomb should have been dropped on Hiroshima, it certainly radically changed the face of warfare. Research into nuclear weapons continues even today, and most modern nuclear bombs are far more powerful than Little Boy and Fat Man.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


@MrsPramm - It was a horrible, tragic thing that happened, but I can't help but feel like the use of Fat Man and Little Boy was necessary in order to end the war. It had dragged on for so long and the Japanese just didn't want to surrender. They were willing to keep going as long as it took in order to avoid surrender, no matter how many people died.

Honestly, I don't know what would have happened if they hadn't dropped those bombs, but I don't think that you can outright declare that it was a bad decision. At least, not lightly. It's possible that using them saved lives, even for Japan, in the long run because it forced the end of the war.

But there's no way to really know what might have happened if they hadn't dropped them.


@Ana1234 - I don't see what difference it makes in the end. Calling them Fat Man and Little Boy might seem somewhat disrespectful, but it really changes nothing for the people they killed and the millions more who have had to deal with the fallout after it happened.

I don't think it's even all that widely known that they were called by these nicknames. It seems like the kind of thing soldiers will often do, though, giving an instrument of death an innocuous name in order to help themselves process the idea of it.


I have to say that I really dislike the names they gave these bombs. Calling it the Little Boy bomb seems to make it something like a child's toy or at least a thing that can be used as a lark rather than one of the most serious and dangerous objects of the 20th century.

I know that the military purposely chooses names that won't give away the nature of what they are describing, but in this case I wish they had been a little bit more on the nose.

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