Take a minute to visit the Bulletin of Atomic Scientists website to read this brilliant photo essay on the Tsar Bomba by Associate Professor and Director of the Science and Technology Studies program at the Stevens Institute of Technology Alex Wellerstein. His first book, Restricted Data: The History of Nuclear Secrecy in the United States, was published by the University of Chicago Press in April 2021.
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! 
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.”
Designed to have a maximum explosive yield of 100 million tons (or 100 megatons) of TNT equivalent, the 60,000-pound monster bomb was detonated at only half its strength. Still, at 50 megatons, it was more than 3,300 times as powerful as the atomic bomb that killed at least 70,000 people in Hiroshima, and more than 40 times as powerful as the largest nuclear bomb in the US arsenal today. Its single test represents about one tenth of the total yield of all nuclear weapons ever tested by all nations.
At the time of its detonation, the Tsar Bomba held the world’s attention, largely as an object of infamy, recklessness, and terror. Within two years, though, the Soviet Union and the United States would sign and ratify the Limited Test Ban Treaty, prohibiting atmospheric nuclear weapons testing, and the 50-megaton bomb would fall into relative obscurity.