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Science16 July 1945

The Trinity Test

Also called: Gadget, First nuclear test

Before dawn on 16 July 1945 the world’s first atomic bomb was tested successfully in the New Mexico desert. The mushroom cloud rose 12 kilometres, and Oppenheimer recalled a line from Hindu scripture: "Now I am become Death, the destroyer of worlds."

The Trinity fireball 16 milliseconds after detonation — New Mexico, 16 July 1945
The Trinity fireball 16 milliseconds after detonation — New Mexico, 16 July 1945

Berlyn Brixner / Los Alamos National Laboratory · Public domain · Source

The device tested was the complex plutonium implosion bomb. At 5:29 a.m. on 16 July the "Gadget" exploded atop a 30-metre steel tower in the Jornada del Muerto ("dead man’s journey") desert. With the force of some 20,000 tons of TNT it vaporised the tower; the flash was seen hundreds of kilometres away and the sand melted into green glass (trinitite).

Oppenheimer later said that a line from the Bhagavad Gita came to him: "Now I am become Death, the destroyer of worlds." News of the success reached Truman at the Potsdam Conference, and on 24 July he casually told Stalin of "a new weapon of unusual destructive force". People living near the site were told nothing of the radioactive fallout.

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States and rulers at the time
United States — President Harry S. Truman
Places
Trinity Site

People

  • J. Robert Oppenheimer1904 – 1967

    key figure · American physicist who directed the Los Alamos laboratory and led the building of the atomic bomb — the "father of the atomic bomb" — and after the war opposed the hydrogen bomb

  • Leslie Groves1896 – 1970

    commander · US Army general who oversaw the building of the Pentagon and from 1942 commanded the whole Manhattan Project

  • Harry S. Truman1884 – 1972

    related figure · 33rd US president (1945–1953) who ordered the atomic bombings, set the policy of containment with the Truman Doctrine and sent US forces to the Korean War

Before and after

Earlier
1943 The Los Alamos Laboratory

Themes that include this event

  • The Birth of the Atomic Bomb1938 – 1949

    From the discovery of fission to the first Soviet bomb — Einstein’s letter, the Manhattan Project, the Trinity test, Hiroshima and Nagasaki, and the dawn of the nuclear age