The first test of a thermonuclear, or fusion, bomb took place on November 1952 at Enewetak Island. Nicknamed Ivy Mike, the huge eighty-two-ton device was more of a building than a usable nuclear device. The device registered a yield of 10.4 megatons, or the equivalent of 10,400,000 tons of TNT. (Hiroshima, by contrast, was roughly eighteen thousand tons of TNT.) Ivy Mike was the biggest test by far, creating a fireball 1.8 miles wide and a mushroom cloud that rose to an altitude of 135,000 feet.