Stunning images show the radioactive cloud formed after the 3‑8 megaton thermonuclear explosion carried out during Operation Red Wing near Bikini Atoll in the Marshall Islands on May 21, 1956. The blast, one of the first air‑launched hydrogen‑bomb tests from a B‑52 bomber at an altitude of 1,320 metres, released energy equivalent to 3‑8 million tons of TNT—about 250 times the Hiroshima bomb—and produced a mushroom cloud that rose more than 28 kilometres. Temperatures at the fireball’s core reached tens of millions of degrees Celsius, with the majority of the energy derived from hydrogen fusion and uranium fission.