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On 6 and 9 August 1945, the United States detonated two atomic bombs over the Japanese cities of Hiroshima and Nagasaki. The bombings killed between 129,000 and 226,000 people, most of whom were civilians, and remain the only use of nuclear weapons in an armed conflict.
- Nuclear Bombs and Hydrogen Bombs
- Manhattan Project
- Who Invented The Atomic Bomb?
- Hiroshima and Nagasaki Bombings
- The Cold War
- Cuban Missile Crisis
- Three Mile Island
- Nuclear Non-Proliferation Treaty
- Illegal Nuclear Weapon States
- North Korea
A discovery by nuclear physicists in a laboratory in Berlin, Germany, in 1938 made the first atomic bomb possible, after Otto Hahn, Lise Meitner and Fritz Strassman discovered nuclear fission. In nuclear fission, the nucleus of an atom of radioactive material splits into two or more smaller nuclei, which causes a sudden, powerful release of energy....
On December 28, 1942, President Franklin D. Roosevelt authorized the formation of the Manhattan Projectto bring together various scientists and military officials working on nuclear research. The Manhattan Project was the code name for the American-led effort to develop a functional atomic bomb during World War II. The project was started in respon...
Much of the work in the Manhattan Project was performed in Los Alamos, New Mexico, under the direction of theoretical physicist J. Robert Oppenheimer, the “father of the atomic bomb.” On July 16, 1945, in a remote desert location near Alamogordo, New Mexico, the first atomic bomb was successfully detonated—the Trinity Test. It created an enormous m...
Scientists at Los Alamos had developed two distinct types of atomic bombs by 1945—a uranium-based design called “the Little Boy” and a plutonium-based weapon called “the Fat Man.” (Uranium and plutonium are both radioactive elements.) While the war in Europe had ended in April, fighting in the Pacific continued between Japanese forces and U.S. troo...
The United States was the only country with nuclear weaponry in the years immediately following World War II. The Soviet Unioninitially lacked the knowledge and raw materials to build nuclear warheads. Within just a few years, however, the U.S.S.R. had obtained—through a network of spies engaging in international espionage—blueprints of a fission-s...
Over the next few decades, each world superpower would stockpile tens of thousands of nuclear warheads. Other countries, including Great Britain, France, and China, developed nuclear weapons during this time, too. To many observers, the world appeared on the brink of nuclear war in October of 1962. The Soviet Union had installed nuclear-armed missi...
Many Americans became concerned about the health and environmental effects of nuclear fallout—the radiation left in the environment after a nuclear blast—in the wake of World War II and after extensive nuclear weapons testing in the Pacific during the 1940s and 1950s. The antinuclear movement emerged as a social movement in 1961 at the height of th...
The United States and Soviet Union took the lead in negotiating an international agreement to halt the further spread of nuclear weapons in 1968. The Treaty on the Non-Proliferation of Nuclear Weapons(also called the Non-Proliferation Treaty or NPT) went into effect in 1970. It separated the world’s countries into two groups—nuclear weapons states ...
Some countries wanted the option of developing their own nuclear weapons arsenal and never signed the NPT. India was the first country outside of the NPT to test a nuclear weapon in 1974. Other non-signatories to the NTP include: Pakistan, Israeland South Sudan. Pakistan has a known nuclear weapons program. Israel is widely believed to possess nucl...
North Koreainitially signed the NPT treaty, but announced its withdrawal from the agreement in 2003. Since 2006, North Korea has openly tested nuclear weapons, drawing sanctions from various nations and international bodies. North Korea tested two long-range intercontinental ballistic missiles in 2017—one reportedly capable of reaching the United S...
- Missy Sullivan
- 1 min
May 13, 2024 · atomic bombings of Hiroshima and Nagasaki, during World War II, American bombing raids on the Japanese cities of Hiroshima (August 6, 1945) and Nagasaki (August 9, 1945) that marked the first use of atomic weapons in war. Tens of thousands were killed in the initial explosions and many more would later succumb to radiation poisoning.
- The Editors of Encyclopaedia Britannica
Mar 7, 2016 · Humans 07 March 2016. By Peter Dockrill. Esri UK. On 16 July 1945, Trinity – the first nuclear explosion ever – was conducted by the US Army in the Jornada del Muerto desert, New Mexico.
atomic bomb, weapon with great explosive power that results from the sudden release of energy upon the splitting, or fission, of the nuclei of a heavy element such as plutonium or uranium.
- The Editors of Encyclopaedia Britannica
Nov 18, 2009 · The plane dropped the bomb—known as “Little Boy”—by parachute at 8:15 in the morning, and it exploded 2,000 feet above Hiroshima in a blast equal to 12-15,000 tons of TNT, destroying five square...
Weapons whose explosive output is exclusively from fission reactions are commonly referred to as atomic bombs or atom bombs (abbreviated as A-bombs ). This has long been noted as something of a misnomer, as their energy comes from the nucleus of the atom, just as it does with fusion weapons.
