Hiroshimaites are glass-like spheres of fallout debris found in Hiroshima, where conditions created by the atomic bomb forged a previously unknown metal alloy with a unique crystal structure.

Nine eyewitness accounts of Hiroshima and Nagasaki survivors

Japan's Hiroshima and Nagasaki became the first cities in history to be hit with nuclear weapons, where tens of thousands of civilians were killed nearly instantly. Hundreds of thousands of people who survived the bombings—referred to as hibakusha—dealt with wounds, radiation poisoning, and alienation from a society unable to process what had happened. This collection of accounts lets nine of those survivors speak, including one of the 165 survivors of both bombings.

While both are nuclear weapons, atomic bombs release nuclear energy by splitting large atomic nuclei, whereas hydrogen bombs derive most of their energy from fusing heavy hydrogen isotopes.

Experiments suggest nuking a metal-rich asteroid may strengthen it

Scientists exposed meteorite samples to proton irradiation at CERN to mimic the effects of a nuclear detonation. The material exhibited greater resistance to breaking after the exposure, suggesting nuclear weapons may better serve to deflect asteroids, not break them.

The H-bomb is hundreds of times more powerful than the bomb dropped on Hiroshima

Unlike the atomic bombs dropped on Hiroshima, which relied on nuclear fission, the hydrogen bomb uses fusion to unleash vastly greater destructive power. Developed by both superpowers in the 1950s, it gave each the ability to destroy entire cities in seconds.

John Hersey’s ‘Hiroshima’ focused on the stories of atomic bomb victims

The nonfiction book is considered one of the earliest pieces of New Journalism and an arresting case against nuclear warfare. Describing the pain, wounds and trauma of six ordinary citizens, “Hiroshima” played a powerful role in American perception of the war by focusing on its human toll.

The story of the Manhattan Project's unused demon core

A 3-inch, 14-pound sphere of nuclear reactive plutonium-gallium was set to be delivered to the Pacific Theater in 1945 to become the third atomic bomb dropped over Japan. When Japan surrendered, it was returned to Los Alamos in New Mexico for experiment, where two scientists would die testing whether the core could reach criticality—where it would release intense energy—via the use of a dense reflector. Watch the story here.

On August 6, 1945, the Enola Gay dropped the first atomic bomb used in warfare on Hiroshima, Japan, killing at least 80,000 people instantly.

How gold, platinum, and many rare earth elements form during neutron star mergers

While massive stars naturally fuse elements as heavy as iron, an analysis of gravitational waves from the collision of two neutron stars revealed that more massive elements are created in this environment via rapid neutron capture—the r-process. This phenomenon sees existing iron nuclei absorb plentiful free neutrons, many of which decay into protons, creating new elements.

In 1962, the US detonated a nuclear weapon in space, which produced an electromagnetic pulse that disabled three low Earth orbit satellites and damaged electrical equipment in Hawaii.

Although they rely on radioactive elements to operate, everyday technologies such as electronic exit signs, some wristwatches, and smoke detectors are not dangerous, unless they are damaged and their radioactive material is inhaled or swallowed.

The atomic bombs dropped on Japan had massive human costs

The US atomic bombings of Hiroshima and Nagasaki in August 1945 killed around 210,000 people—more than 38,000 of them estimated to be children—with tens of thousands more later dying from radiation-linked illnesses, leaving lifelong trauma and increased cancer risks.

Visualizing the chemistry of nuclear weapons

Nuclear weapons have devastating effects, but the science of how they work is atomically small. There are two main types of nuclear reaction: fission and fusion. The fission bomb produces immense energy by splitting an atom, the result of firing a...

The discovery of the neutron paved the way for nuclear weapons

In 1932, James Chadwick discovered the subatomic particle when trying to explain the radiation emitted by beryllium after it was bombarded with alpha particles. The radiation’s ability to eject protons from a target suggested a chargeless particle with slightly more mass than a proton.

Simulate the impact of an antimatter bomb around the world

Using "Total Annihilator," users can click on a location on the map, select the antimatter mass, and the observation altitude before detonating the bomb. Scrolling through the left sidebar reveals the impacts of the detonation, including the sizes of the resulting fireball and thermal pulse, the spread of ionizing radiation, and the atmospheric effects.

Build atomic nuclei to explore their instability and resulting radioactive decay

In this simulation, users can add protons and neutrons to create an atomic nucleus, view its half-life and decay options, and identify patterns in how specific combinations of particles create extremely stable nuclei, from which the nuclear shell model of stability emerged.

Oppenheimer reflected on the atomic bomb's legacy two decades later

In a 1965 CBS interview, J. Robert Oppenheimer discussed his role as Los Alamos director, expressing deeply mixed feelings about Hiroshima and Nagasaki and reflecting on how nuclear weapons had transformed the world since their first use.

The Manhattan Project operated at three key sites, each with a distinct role in building the first atomic bomb.

Craters found on the moon and the calculated dates of these impacts, based on rocks returned by the Apollo missions, suggest that Earth was pummeled by asteroids for millions of years—a period known as the Late Heavy Bombardment.

Ernest Rutherford's gold foil and nitrogen experiments revealed nuclear structure

Observing high-angle deflections when alpha particles were fired at gold foil led to an atomic model with a dense, positively charged nucleus. Firing those particles at nitrogen resulted in the emission of hydrogen nuclei—protons—leading to the discovery of the subatomic particle.

The 'Elephant's Foot' in Chernobyl is part of the largest documented mass of corium

The nuclear disaster produced around 200 tons of nuclear fuel that mixed with the surrounding melted reactor core materials. As of 2025, corium has been naturally formed four other times in history: once during the Three Mile Island accident and three times at the Fukushima Daiichi plant disaster.

The death toll of the atomic bombings in Japan remains disputed, with estimates ranging from 110,000 to 210,000.

Fusion reactions and radioactive decay produce elements inside stars

Hydrogen, present since the early universe, serves as fuel for the proton-proton chain, producing helium, which is then incorporated into the CNO cycle to produce carbon, nitrogen, and oxygen. Additional fusions of helium with these elements and subsequent decays via the alpha ladder produce elements up to iron and bismuth.

Every day, lightning releases several Hiroshima bombs' worth of energy into the atmosphere

If all this lightning struck one location at once, the bolt would be the diameter of the center circle of a basketball court, turning the entire court into a crater. Its heat would ignite surfaces for miles around, and its shockwave would demolish buildings.

The Manhattan Project, the top-secret American program that built the world's first atomic bomb, cost $27B in today's dollars and reshaped global power.

The discovery of nuclear fission was facilitated by the discovery of the neutron

The discovery of the neutron provided scientists with a particle that could penetrate the nucleus and advance atomic physics. Otto Hahn was the sole Nobel recipient for the discovery of fission, despite collaborating with Lise Meitner and Fritz Strassmann.

Kurt Vonnegut's 'Cat's Cradle' was inspired by the bombing of Hiroshima

The writer fought in World War II and witnessed the firebombing of Dresden, which he recounted in 1969's satirical "Slaughterhouse Five." Six years earlier, though, he wrote about the bombing of Hiroshima in "Cat's Cradle," channeling some of the horror he witnessed in Dresden to write about the dropping of the atomic bomb. (Some users may experience a paywall.)

Interviews from the Manhattan Project

This is an archive of interviews with people who worked on and were impacted by the Manhattan Project, the World War II-era effort that resulted in the atomic bomb. Listen to the "father of the atomic bomb," Julius Robert Oppenheimer, describe his daily routine during the project, which he reports officially started Dec. 6, 1941. This archive also includes interviews with survivors of the Hiroshima and Nagasaki bombings.

During the Cold War, a mid-air fire led to a nuclear bomber crash in Greenland that left a piece of a hydrogen bomb missing to this day.

View the evolution of atomic models, with four successively overturned between 1900 and 1926

Originally thought to be indivisible spheres unique to each element, the discovery of the electron by J.J. Thomson revealed them to be made of smaller particles. Ernest Rutherford's gold foil experiment uncovered the existence of nuclei, which Niels Bohr suggested were surrounded by electrons in fixed orbits. By applying quantum mechanics, Erwin Schrödinger replaced orbits with probability clouds.

Methods for disposing of nuclear waste include melting it into a liquid to create glass, dumping it into graphite blocks, storing it in lead-lined rooms, and submerging it in deep pools of water.

The origin of atmospheric science while testing nuclear weapons during the Cold War

The arms race between the US and the Soviet Union saw both countries stockpiling and detonating hundreds of bombs underground, underwater, and in the atmosphere. To better predict where nuclear fallout would travel after these tests, scientists developed models that would serve as a foundation for those used to explain atmospheric circulation.

While the leading hypothesis for the moon's origin involves a Mars-sized object called Theia striking ancient Earth and forming from the resulting debris, it cannot explain why lunar isotope abundances match Earth.

More than 90% of the atoms in the human body were forged by stars

Excluding all of the universe's hydrogen and most of its helium and lithium that formed in the Big Bang, elements found in significant amounts in our bodies formed through nuclear fusion within stars, collisions between neutron stars, or stars undergoing supernova. For example, all of the oxygen (65% of our mass) came from massive stars exploding.

View the periodic table of radioactive elements, and a list of each's most stable isotopes

Technetium is the lightest artificial radioactive element, which is produced primarily as a byproduct of nuclear fission. Several unstable isotopes are commercially available to medical professionals and scientists, despite their radioactivity risks.

Meet the scientists who worked on the Manhattan Project.

Nitinol is an example of a shape memory alloy, which can be trained to 'remember' a specific shape and, if deformed, revert to it upon being heated.