Biggest nuclear tests in history: Tsar Bomba, Castle Bravo and their global impact

Edited By Kushal Deb : Aug 25, 2025, https://www.wionews.com/photos/biggest-nuclear-tests-tsar-bomba-castle-bravo-global-impact-1756122889360/1756122889362

Tsar Bomba

Tsar Bomba is the most powerful nuclear test in the history of nuclear weapons. A Soviet Tu-95 bomber dropped it from 13,000 feet, accompanied by a parachute, in Novaya Zemlya, a remote archipelago in the northern fringes of the U.S.S.R., on October 30, 1961, at around 11.32 am in Moscow time. Yielding nearly 50 megatons, it produced mushroom clouds over 40 miles high and 25 miles from end to end and equivalent to the explosion of 57 million tons of TNT. Houses within a 20km radius were completely destroyed. A 5-5.5 magnitude seismic event was felt across the world. The explosion’s shockwave circled the Earth three times and broke windows as far as 1,000 km away.

The Soviet Union was condemned unanimously by Great Britain, Sweden, and the United States. Glaciers around Novaya Zemlya were found with elevated levels of radiation because of the blast. In the following years Soviet Union and the United States signed several treaties, namely the Partial Test Ban Treaty (1963), to restrict the development of nuclear weapons. It banned nuclear weapons tests in the atmosphere, outer space, and underwater; only underground testing was allowed. Several other treaties followed, like the Outer Space Treaty (1967) prohibited placing nuclear weapons in orbit or testing them in space, Treaty on the Prohibition of Nuclear Weapons in Latin America (1967), establishing Latin America as a nuclear-weapon-free zone.

Castle Bravo

The US tested its first dry Thermonuclear device on March 1, 1954, in the Marshal Islands. Castle Bravo, with a 15 megaton yield, had produced a mushroom cloud that grew to nearly four-and-a-half miles wide and reached a height of 130,000 feet six minutes after the detonation.

Scientists have terribly miscalculated its capacity, intended to be a 5–6 megaton detonation, following the impact, radioactive fallout contaminated surrounding islands, exposing locals and U.S. personnel to dangerous radiation levels. An estimation states that 665 inhabitants of the Marshall Islands were overexposed to radiation. The fallout spread over 7,000 square miles. Europe, Australia, India, and Japan all found traces of radioactive material, starting a widespread outcry for a Nuclear Testing ban.

Castle Yanke

It was tested on May 5, 1954, at Bikini Atoll in the Marshall Islands. It was part of the Castle series tests, of which Ivy Mike and Castle Romeo were a part. Yanke contributed a yield of approximately 13–13.5 megatons, vaporised the test island, and generated a mushroom cloud affectionately estimated at 43 km in height. Although the yield of Castle Yankee was smaller than Castle Bravo, it still contributed to radioactive fallout in the nearby areas around the atoll.

Castle Romeo

Castle Romeo was tested by the US on March 26, 1954, just after the test of Castle Bravo. It yielded 11 megatons of TNT after the explosion, and the extreme red, orange, and yellow hues cloud became a popular representation of the nuclear explosion in the media. This thermonuclear test caused extensive radioactive contamination in the Pacific.

Ivy Mike

Ivy Mike was the world’s first successful hydrogen bomb test. The test marked a shift from fission-based weapons to fusion technology. It also pushed the Soviet Union to accelerate its thermonuclear program. It was also detonated in the Marshal Islands on November 1, 1952. The explosion produced 10.4 megatons of TNT. It spread across 1.8 to 3.2 miles and rose above 25 miles.