Tsar Bomba (Russian: Царь-бомба) was the largest nuclear explosive device in history. It was detonated on October 30, 1961 as a test; this took place at a height of 4000 metres over the Novaya Zemlya Nuclear Range at the Novaya Zemlya Island in the Arctic Sea; it was dropped from a Tu-95 bomber.
The name (Russian, Tsar-bomb) was coined in an analogy with Tsar Kolokol, an extraordinarily large bell and Tsar Cannon, an extraordinarily large howitzer. The bomb was meant for the same purpose. During its development the bomb was actually nicknamed Ivan.
It was a fusion bomb with a yield of ~50 megatons (the original US estimate was 57 megatons, though since 1991 all Russian sources have cited it as "only" 50 megatons ), though the design was capable of approximately 100 megatons. It was purposely reduced shortly before the launch, though Nikita Khrushchev initially reported a yield of 100Mt, and cited this number in his speeches. The nuclear devices of the type used in the bomb were designed by a team of physicists headed by Academician Igor Kurchatov, which included Andrei Sakharov, Victor Adamsky , Yuri Babayev , Yuri Smirnov , and Yuri Trutnev (А.Д.Сахаров, В.Б.Адамский, Ю.Н.Бабаев, Ю.Н.Смирнов, Ю.А.Трутнев).
It was not intended for actual use in warfare; it was developed and tested as part of the sabre-rattling between the Soviet Union and United States in the course of the Cold War. The launch date was matched to the time of the XXII Congress of the CPSU.
Excluding the nuclear device, Tsar Bomba was designed and constructed in only 14 weeks after Soviet premier Nikita Khrushchev initiated the project on July 10, 1961. The bomb itself weighed 27 tonnes and was 8 metres long by 2 metres wide; a special parachute (of weight 0.8 tonne) had to be designed to allow it to be dropped from an airplane. A possibly apocryphal story claims that the fabrication of this parachute required so much raw nylon that the negligible Soviet nylon hosiery industry was noticeably disrupted.
The Tsar Bomba had its yield scaled down by replacing the uranium fusion tamper (which amplifies the reaction greatly) with one made of lead to eliminate fast fission by the fusion neutrons. For this reason it was actually a very "clean" test, with over 90% of the energy coming from fusion rather than fission (fusion produces little fallout).
Tsar Bomba was detonated on October 30, 1961 over the nuclear testing range at Novaya Zemlya Island in the Arctic Sea. It was dropped from a Tu-95 bomber at 11:30 a.m. at 10,500 metres altitude by pilot A. E. Durnovtsev. The bomb was detonated at 11:33 a.m. with the aid of barometric sensors at the height 4,000 metres over the land surface (4,200 over the sea level). The fireball touched the ground and reached nearly as high as the release plane. Light from the detonation was visible 1000 km away; the mushroom cloud rose as high as 14-16 km and developed to the width of 30-40 km.
The 50-Mt test was hot enough to have induced third degree burns at 100 km, and atmospheric irregularities caused blast damage up to 1000 km away (due to atmospheric focusing, where localized regions of destructive blast damage can be created many hundreds of kilometers away); the "dirty" 100-Mt version would have laid lethal radioactivity over an enormous area.
A bomb of this magnitude has tremendous "blowback" potential to its user, while at the same time being inefficient in radiating much of its energy out into space. Modern nuclear-weapon tactics call for multiple relatively smaller bombs to produce more damage on the ground (for example, MIRVs). It was not practical for use as a weapon in wartime, requiring a specially modified bomber that could not be used to deliver the massive bomb to a distant target.
Because the Tsar Bomba is the highest energy device ever detonated it also represents the highest power device ever used by humans. Since 50 Mt is 2.1x1017 Joules the power produced during the burn was around 5.3x1024 watts or 5.3 yottawatts. This represents a power just greater than one percent of the entire power output of the Sun (386 yottawatts)!