The largest nuclear weapon ever detonated was known as tsar bomba, or RDS-220 (code name Big Ivan), and it produced the most powerful man-made explosion ever recorded. Detonated in a test over Novaya Zemlya in October 1961, it had a yield of 50 megatons, more than ten times the power of the two atomic devices dropped on Hiroshima and Nagasaki. The blast, which was seen from as far away as Norway and Finland, produced a mushroom cloud 25 miles wide at its base and 60 miles high, and vaporized anything within three dozen miles of the impact site—and shattered windows in distant cities. Radioactive particles laced the atmosphere, but scientists assured the public that most of the bomb’s fallout would stay high in the stratosphere and would disintegrate by the time it reached Earth.

The Tsar Bomba: Unveiling the Power and Impact of the World’s Largest Nuclear Bomb

Tsar Bomba’s spectacular destruction prompted worldwide condemnation, and the Soviet Union was forced to tone down future tests. Andrei Sakharov, horrified not only by Tsar Bomba’s power but also by the cumulative effect of open-air nuclear tests in the United States and Great Britain, became a leading advocate for limiting atomic weapons testing to underground sites.

It’s easy to dismiss Tsar Bomba as a macabre curiosity of the Cold War, but recently declassified files and memoirs reveal that its design was taken more seriously than previously thought, and that its potential as a weapon was a lot higher than the U.S. government was willing to admit at the time. It’s a reminder that very high-yield nuclear weapons aren’t necessary for deterrence—and that such exploration can be dangerous, wasteful, and pointless.