After the Soviet Union detonated a 50-megaton bomb over an uninhabited island north of the Arctic Circle on October 30, 1961, it was clear that human beings would need to consciously decide that atomic yields had reached a dangerous saturation point. Science had imposed no such limits. The Tzar Bomba was a glimpse of just how enormous a human-made nuclear explosion could be.
Its yield of 50 megatons, or 5,000 kilotons, was equal to 3,800 of the bombs dropped on Hiroshima. "The mushroom cloud reached a height of 60 kilometers [37 miles]," according to the website of the Comprehensive Test-Ban Treaty Organization. "Third-degree burns were possible at a distance of hundreds of kilometres. The ring of absolute destruction had a 35 km [28-mile] radius."
The Tzar Bomba's fireball was over 5 miles in width. According to the Nukemap, a project of nuclear historian Alex Wellerstein, if the Tzar Bomba were dropped over Business Insider's headquarters at 20th St and 5th Ave in Manhattan, the "radiation zone" in which between 50% and 90% of people would die if they didn't receive medical assistance would stretch from north of Times Square to south of the Brooklyn Bridge, while the fireball would stretch from Brooklyn Heights to the Natural History Museum: