The Biggest Bomb

In 1961, at the height of the Cold War, the Soviet Union detonated the largest hydrogen bomb ever tested. At 50 megatons, it was thousands of times larger than the bombs that destroyed Hiroshima and Nagasaki. And it could have been larger, but concerns over the spread of fallout caused the designers to scale back the size of the explosion. 

The Bulletin of the Atomic Scientists has published a well-documented (with footnotes) history of the development of the bomb, often known as the Tsar Bomba. It's a rather unnerving story that highlights the craziness of those years.

In the early hours of October 30, 1961, a bomber took off from an airstrip in northern Russia and began its flight through cloudy skies over the frigid Arctic island of Novaya Zemlya. Slung below the plane’s belly was a nuclear bomb the size of a small school bus—the largest and most powerful bomb ever created.

At 11:32 a.m., the bombardier released the weapon. As the bomb fell, an enormous parachute unfurled to slow its descent, giving the pilot time to retreat to a safe distance. A minute or so later, the bomb detonated. A cameraman watching from the island recalled:

A fire-red ball of enormous size rose and grew. It grew larger and larger, and when it reached enormous size, it went up. Behind it, like a funnel, the whole earth seemed to be drawn in. The sight was fantastic, unreal, and the fireball looked like some other planet. It was an unearthly spectacle! [1]

The flash alone lasted more than a minute. The fireball expanded to nearly six miles in diameter—large enough to include the entire urban core of Washington or San Francisco, or all of midtown and downtown Manhattan. Over several minutes it rose and mushroomed into a massive cloud. Within ten minutes, it had reached a height of 42 miles and a diameter of some 60 miles. One civilian witness remarked that it was “as if the Earth was killed.” Decades later, the weapon would be given the name it is most commonly known by today: Tsar Bomba, meaning “emperor bomb.”