The nuclear arms race that originated in the race for atomic weapons during World War II reached a culminating point on October 30, 1961, with the detonation of the Tsar Bomba, the largest and most powerful nuclear weapon ever constructed.

The bomb would be attached to a parachute to slow its descent to detonation at 13,000 feet,

The detonation was astronomically powerful—over 1,570 times more powerful, in fact, than the combined two bombs dropped on Hiroshima and Nagasaki. The Tsar Bomba’s yield was 50 megatons: ten times more powerful than all of the ordnance exploded during the whole of World War II. The mushroom cloud was 25 miles wide at its base and almost 60 miles wide at its top. At 40 miles high, it penetrated the stratosphere.

The resulting radioactive fallout might have been catastrophic, not just for the Soviet Union but for its neighbors. And it would have, if the Tsar Bomba’s original concept—yielding an almost inconceivable 100 megatons—had been pursued. Fortunately, because of the height at which the device was detonated, the accompanying five-mile-wide fireball was repelled away from the surface by the force of its own shockwave and did not make contact with the earth, …