The 1961 USSR hydrogen bomb

The world's most powerful hydrogen bomb, Tsar Bomba (Царь-бомба) or Изделие 202, was detonated on the 30th of October 1961 at 11:32 GMT+03:00, over Novaya Zemlya (Новая Земля) island in northern Russia above the Arctic Circle. The bomb had an explosive force of 58 megatons, which remains unsurpassed in terms of its yield. This device was distinguished by its purity: 97 percent of its energy yield was derived from thermonuclear reactions. The explosive force war almost 6,000 times more powerful than the Hiroshima (広島) bomb, or the equivalent of more than 50 million tons of TNT — 10 times the total power of all explosives used during World War II, including the atomic bombs dropped on Japanese cities by the United States. The bomb was dropped by TU-95V (Ту-95В) strategic bomber, and detonated 4000 metres above the surface. The atmospheric disturbance generated by the explosion orbited the earth three times. The flash of light was so bright that it was visible at a distance of 1,000 kilometers, despite cloudy skies. A gigantic, swirling mushroom cloud rose as high as 64 kilometers.