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Russia's invasion of Ukraine has led to a sense of panic around the world, with many harbouring memories of the Soviet Union's Tsar Bomba and the impact this had back on October 30, 1961.
The thermonuclear bomb was dropped over Novaya Zemlya Island, deep in the Arctic Ocean, in the most extreme north-eastern part of Europe.
The Tsar Bomba is the most powerful thermonuclear weapon ever detonated, as no other bomb as strong has ever been tested.
While there were no deaths from the Tsar Bomba's test, there were windows shattered due to the explosion 780km (480 miles) away in a village on Dikson Island.
However, in the aftermath of the Cuban Missile Crisis, then-US president John F. Kennedy managed to convince the Soviet Union to limit nuclear testing to underground sites.
Then, on October 7, 1963, the United States, the United Kingdom and the Soviet Union signed the Partial Nuclear Test Ban Treaty, which forbade tests in the atmosphere, outer space and underwater.
As such, with the signing of this treaty, these countries ensured that no one would detonate a Tsar Bomba-style weapon ever again.
Is the Tsar Bomba still the most powerful nuclear weapon?
This is a bit of a difficult question to answer, as other nuclear weapons have not been tested in practice, even if it has been 50 years since the Tsar Bomba was detonated.
However, the Soviet Union developed three AN602 physics packages at 101.5 megatons (Mt) and these are more powerful than the Tsar Bomba, which was downscaled to 51 Mt before being used RDS-220 Vanya.
The remaining two AN602 packages were used in the 8F117 warheads, and these were set to be placed on top of the UR-500 Gerkules ICBM.
The UR-500 ICBM was successfully tested but never deployed, with it being further developed into the famous Proton rocket.
Therefore, Russia has a weapon that is almost twice as deadly as the Tsar Bomba, as well as an ICBM to use it.
On October 30, 1961, the Soviet Union tested the largest nuclear device ever created. The "Tsar Bomba," as it became known, was 10 times more powerful than all the munitions used during World War II.
While its original purpose was to prove to the world, and especially to the United States, that the Soviet Union was capable of producing such devices, it also brought a surprising twist to the future testing of nukes.
The Military Race Is On
At the beginning of the 1960s, the relationship between the Soviet Union and the United States was tense -- the countries were in the middle of the Cold War, struggling for geopolitical, ideological, and military dominance.
The United States had already tested the world's first hydrogen bomb -- called "Mike" -- in 1952 and their biggest nuclear device -- called "Castle Bravo" -- in 1954. The Soviet Union was also working on developing a hydrogen bomb and managed to detonate its first true one in 1955. But that was just the beginning. Soviet leader Nikita Khrushchev was keen to show off the U.S.S.R.'s military prowess, so he ordered the creation of the most powerful bomb ever made.
Who Was Who In Creating The 'Tsar Bomba'?
How Does A Hydrogen Bomb Work?
The Tsar Bomba was a hydrogen aerial bomb, also known as a thermonuclear weapon, which is usually described as a more advanced and powerful version of an atomic bomb. While atomic bombs use either uranium or plutonium in most cases, hydrogen bombs also need additional isotopes of hydrogen, called deuterium and tritium.
The reaction that causes the explosion is also different. Atomic bombs rely on fission -- a process of compressing the core of uranium or plutonium, splitting it into parts, and therefore releasing a huge amount of energy. On the other hand, hydrogen bombs use not only the energy from fission but also secondary fusion, which makes the explosion much stronger.
Specifications of various hydrogen bombs vary. For example, Soviet scientist and dissident Andrei Sakharov, a member of the Soviet nuclear weapons program, came up with a design called "sloika" (layer cake). This method used alternating layers of deuterium (an isotope of hydrogen) and uranium. It was a major contribution to the development of the hydrogen bomb in the Soviet Union.
What Did The Most Powerful Bomb Look Like?
The Tsar Bomba was given many technical names, such as Project 27000, Product Code 202, and RDS-220. It was 8 meters long, its diameter was about 2 meters, and it weighed roughly 25 tons. Its proportions made it very challenging to handle. It was so large that it couldn't be loaded on any plane that the Soviet Union had at that time.
Testing the "Tsar Bomba": The World's Most Powerful Nuclear Bomb
Originally, the bomb was supposed to yield up to 100 megatons, but scientists were concerned about radioactive fallout and potential effects on human health. That's why they eventually decided to use three layers of lead (instead of three uranium layers) and halve the explosion.
Tsar Bomba Scheme
The Day Of The Explosion
On October 30, 1961, a Tupolev Tu-95 plane started its journey from the Olenya airfield on the Kola Peninsula. Although it was the largest plane in the Soviet fleet, it had never carried such a heavy weapon and had to be modified. Nonetheless, the bomb would not fit inside the plane and had to be placed underneath it. In order to reflect the heat caused by the blast, the plane was painted bright white.
Its pilot, Major Andrei Durnovtsev, climbed to 10 kilometers above the ground and flew toward the Matochkin Strait at Novaya Zemlya. He was accompanied by another plane, a Tu-16 bomber, which was supposed to film the blast.
The Tsar Bomba was dropped above the Arctic archipelago of Novaya Zemlya. To give the planes some time to escape the scene, the bomb was equipped with a parachute that was supposed to slow down its fall and make sure the bomb exploded at 4,000 meters. Despite all of the precautions, the survival rate of the crew was calculated at about 50 percent.
At 11:32 a.m. Moscow time, the bomb exploded. It created a fireball about 8 kilometers wide and the flash could be seen from 1,000 kilometers away. All buildings within 55 kilometers of the test site at Sukhoy Nos were completely destroyed; windows within hundreds of kilometers were broken. The shock wave generated after the blast traveled three times around the Earth. It also made the Tu-95 plane drop about 1,000 meters, but the pilot later managed to regain control and landed safely.
The explosion produced about 57,000 kilotons of energy. In comparison, the bombs dropped on Hiroshima and Nagasaki during World War II were equivalent to 15 and 21 kilotons, respectively. The largest nuclear device tested by the United States was 15,000 kilotons.
The bomb's mushroom cloud climbed to 60 to 70 kilometers above the ground. Luckily, the fireball didn't make contact with the Earth, and therefore the level of radiation was relatively small, compared to the size of the bomb. According to some sources, however, radioactive fallout was measured across Scandinavia.
Comparison Of Mushroom Cloud Heights
Selected detonations, in kilometers
What Happened Next?
After the Tsar Bomba had been tested in 1961, nuclear tests continued and Soviet leader Nikita Khrushchev even ordered the detonation of another megaton bomb just a few months later. The following year, the testing reached its peak when a total of 79 nuclear bombs were detonated. However, efforts to end the atmospheric testing of nuclear weapons were also on the rise.
Nuclear Tests By Country
(Atmospheric and underground)
In 1963, the United States, the United Kingdom, and the Soviet Union signed the Partial Nuclear Test Ban Treaty, which prohibited tests in the atmosphere, outer space, and underwater. The deal was later opened to other countries as well. From that point onward, nuclear tests were conducted underground.
Nuclear Test Sites
(Sites with the highest number of tests included)
The Soviet Union conducted its last nuclear test in 1990, the United States in 1992. Four years later, the Comprehensive Nuclear Test Ban Treaty banned nuclear weapons tests in all environments.
Sources: RFE/RL, AFP, Arms Control Association, Atomic Archive, Atomic Heritage Foundation, The Barents Observer, BBC, Federation of American Scientists, The Insider
The United States and Russia now have thousands of nuclear weapons each, with China, France, the United Kingdom, India, Pakistan, North Korea and Israel also having nukes. The ongoing Russian invasion of Ukraine has sparked fears that such nuclear weapons could end up being used.
Here, Live Science takes a look at the most powerful nuclear weapons ever detonated — specifically explosions that exceeded 10 megatons. In comparison, estimates for the Hiroshima bomb are around 15 kilotons. Documents from the U.S. Department of Energy and the Russian Federation's Ministry of Defense revealed plenty of high-energy blasts. Even so, there are a number of nuclear weapon detonations whose yields are uncertain, so only those detonations whose yields are known with confidence are included here. All of these behemoth blasts are many times more powerful than those that were used on Hiroshima and Nagasaki at the end of World War II.
Tsar Bomba
On Oct. 30, 1961, the Soviet Union dropped the most powerful nuclear weapon ever exploded on the archipelago of Novaya Zemlya, north of the arctic circle. Yielding an explosion of 50 megatons the "Tsar Bomba," as it is sometimes called, was about 3,300 times more powerful than the 15 kilotons nuclear weapon dropped on Hiroshima. The hydrogen bomb, designated as the Soviet RDS-220, was also dubbed "Big Ivan" and "Vanya," though "Tsar Bomba" (translated to King of Bombs) is its most popular moniker.
Ironically, the bomb could have been much more powerful. It was designed to have an explosive yield of up to 100 megatons, but it was detonated at 50 megatons, wrote Alex Wellerstein, director of the Science and Technology Studies program at the Stevens Institute of Technology, in an article published in 2021 on the Bulletin of the Atomic Scientists website. The fireball from the explosion was nearly 6 miles (9.7 km) in diameter, which is "large enough to include the entire urban core of Washington or San Francisco, or all of midtown and downtown Manhattan," wrote Wellerstein.
Test 219
On Dec. 24, 1962, the Soviet Union dropped a rather unpleasant Christmas present over the test site on the Novaya Zemlya archipelago — which holds the second largest glacier complex in the Arctic, according to a paper published in 2021 in the journal Nature (opens in new tab). At 24.2 megatons, this nuclear bomb was less than half as powerful as the "Tsar Bomba" bomb but was still the second most powerful nuclear weapon ever detonated. It also about 1,600 times stronger than the bomb dropped on Hiroshima.
Because it was the second most powerful nuclear weapon, it didn't get a catchy nickname like the "Tsar Bomba" did; it is simply referred to as "test 219." Test 219 would be one of the last nuclear bombs dropped from the air by the Soviet Union, as a test ban treaty in 1963 banned aboveground testing and future tests were conducted underground.
Test 147
On Aug. 5, 1962, the Soviet Union dropped a 21.1 megaton over the Novaya Zemlya archipelago (which is part of the Russian Arctic). The third most powerful nuclear detonation in history, it is simply known as "test 147," again not acquiring a nickname like the "Tsar Bomba" did.
This bomb clocks in as being about 1,400 times as powerful as the one dropped on Hiroshima. Despite its immense power this nuclear detonation is not as well known as others on this list.
According to the site Nukemap (opens in new tab), a nuclear weapon like this that was airburst over Central Park, in New York City, would produce a fireball that would cover all of the park and produce an intense wave of thermal radiation that would cover all of the city and reach as far away as Stamford, New York. Nukemap was created by Alex Wellerstein.
Test 173
On Sept. 25, 1962, the Soviet Union dropped a 19.1 megaton nuke over the Novaya Zemlya archipelago. The fourth most powerful nuclear weapon ever detonated it is about 1,270 times more powerful than the Hiroshima bomb. Known simply as "test 173" this bomb never got a nickname.
An interesting note — a few weeks after this bomb was dropped the Cuban Missile Crisis began — a crisis that brought the Soviet Union and United States to the brink of nuclear war. During the crisis the Soviet Union deployed nuclear missiles to Cuba. President Kennedy considered attacking the sites and ultimately ordered a naval blockade to prevent more nuclear weapons from reaching Cuba. The Soviet Union eventually agreed to take down the missiles in exchange for the United States removing their nuclear missiles from Turkey.
Castle Bravo
On March 1, 1954 the United States detonated a 15 megaton nuclear weapon on the Bikini Atoll, in the Marshall Islands, in a test codenamed "Castle Bravo." It was detonated on the surface rather than being dropped by air and is the fifth most powerful nuclear weapon detonation in history.
The yield was about two and half times greater than expected and resulted in nuclear fallout spreading for about 7,000 square miles (18,130 square kilometers) across the Pacific, leaving residents of the Marshall Islands, U.S. military personnel and the crew of a Japanese fishing trawler exposed to a high level of radiation, according to an article published in 2017 by the Atomic Heritage Foundation. Some residents had to be evacuated, and the people of the Marshall Islands suffered an elevated rate of cancer.
The Castle Bravo test, and the harm done to the residents, triggered global protests against the testing of nuclear bombs. In future decades, the U.S. government paid compensation to island residents; retired U.S. military personnel launched a case against the government in 1984, alleging that the American government had downplayed the radiation danger.
Castle Yankee
On May 5, 1954, another nuclear weapon was detonated on a barge beside the Bikini Atoll. The "Castle Yankee" test resulted in a yield of 13.5 megatons. It is the sixth most powerful nuclear weapon ever detonated in history, being about 900 times more powerful than the one dropped on Hiroshima. In the years that followed, global pressure would mount for a ban on nuclear tests to come into place.
The Bikini Atoll is a coral reef that surrounds a lagoon. Prior to nuclear testing, people lived on the atoll. The population was removed before the tests and has never been able to return because the atoll is still contaminated with remains from the radioactive fallout.
Test 123
On Oct. 23, 1961, the Soviet Union dropped a 12.5 megaton bomb on the Novaya Zemlya archipelago, about 830 times as powerful as the Hiroshima bomb. It is the seventh most powerful nuclear weapon detonated in history. Known as "test 123," it was a prelude to the "Tsar Bomba," which would be dropped in the same area just a week later.
According to an article published (opens in new tab) in 1996 in the journal Polar Geography, this archipelago had small populations of people living there prior to nuclear testing. These people engaged in hunting and trapping.
Castle Romeo
On March 26, 1954, a nuclear weapon was detonated on a barge off the Bikini Atoll. It yielded an 11 megaton nuclear explosion that was about 730 times as powerful as the Hiroshima bomb. Codenamed "Castle Romeo," the test was carried out just a few weeks after the Castle Bravo test that had spread radioactive fallout across the Marshall Islands.
According to Nukemap, a nuclear weapon of this intensity airburst over New York City's Central Park would produce a fireball that would cover the park and a wave of intense thermal radiation that would extend as far as Port Chester.
Ivy Mike
On Nov. 1, 1952, "Ivy Mike" or "Mike," would become the first thermonuclear weapon (hydrogen bomb) to be fully detonated — yielding a 10.4 megaton explosion, about 690 times the size of the Hiroshima bomb. It was detonated on the surface of the Enewetak atoll on the Marshall Islands. At the time it was detonated, the Korean War was raging and a nuclear arms race had developed between the United States and Soviet Union.
Whether to develop the hydrogen bomb was a subject of debate within the Truman administration, with some officials pushing against it and others pushing for it, an article on the Atomic Heritage Foundation website noted (opens in new tab), with president Truman ultimately deciding to build it.
Originally published on Live Science.