38. A Quarter of the power of Krakatoa

X is the nickname for the AN602 hydrogen bomb, the most powerful nuclear weapon ever detonated. Developed by the Soviet Union, the bomb was initially designed to have a yield of 100 megatons of TNT, but which was reduced to 50 megatons to avoid a nuclear fallout. Only one bomb was ever built and tested successfully on October 30, 1961, generating a 64km high mushroom cloud and causing complete destruction within a 55km radius. The heat generated could have caused third-degree burns at a distance of 100km, and shockwaves were experienced at distances of 700km. The red circle in the photograph shoes the region of complete destruction, and the yellow circle the area of the fireball, with Paris for an example.

X was also known as Y, a phrase popularized by Z's speech, addressing Richard Nixon in 1959 who was attending an exhibition in Moscow.

Give X, Y and Z.

Z with JFK.