First Atomic Bomb Test
The Trinity test detonated the first nuclear weapon in New Mexico
July 16, 1945
The Gadget
At 5:29 AM on July 16, 1945, a plutonium bomb nicknamed "The Gadget" detonated in the desert of New Mexico at a site called Trinity. The flash was visible 160 miles away. The explosion released energy equivalent to 21,000 tons of TNT. The mushroom cloud rose 12 kilometers into the sky. A steel tower holding the device was vaporized. Sand around the blast fused into green glass, later called trinitite. Robert Oppenheimer, the scientific director of the Manhattan Project, recalled a line from Hindu scripture: "Now I am become death, the destroyer of worlds."
The Manhattan Project
The Trinity test was the culmination of the Manhattan Project — a secret program that began in 1942 and employed 130,000 people across facilities in New Mexico, Tennessee, Washington State, and elsewhere. Scientists from the US, UK, Canada, and Europe — including many Jewish refugees who had fled Nazi Germany — worked in secrecy to build a weapon before Germany could. Germany surrendered before the bomb was ready; Japan did not.
What It Unleashed
Less than a month after Trinity, atomic bombs were dropped on Hiroshima and Nagasaki. The nuclear age — with its Cold War arms race, mutually assured destruction, and constant threat of accidental war — shaped every decade that followed. Nine countries now have nuclear weapons. The scientific knowledge that produced the first nuclear reactor in 1942 was only three years away from producing the most destructive weapon ever used.