Trinity, 16 July 1945: The First Atomic Bomb Test
What happened at the Trinity test? Explore the Manhattan Project’s first nuclear explosion, the people behind it, and the difference between a successful test and its human consequences.
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Communities exposed to fallout
Radioactive fallout from Trinity exposed nearby communities, whose residents are included among those known as downwinders.
Glass formed at test site
The heat of the Trinity explosion fused material at the test site into the glass known as trinitite.
Used a related design
Trinity tested a plutonium implosion design related to the design used in the Fat Man bomb.
Observed the explosion
Enrico Fermi observed the Trinity explosion and estimated its strength from the movement of small pieces of paper in the blast.
Designed the device
Los Alamos Laboratory designed and assembled the plutonium device tested at Trinity.
Organized bomb development
Trinity was the Manhattan Project’s first test of a nuclear explosive device.
Directed the test
Kenneth Bainbridge directed preparations for and execution of the Trinity test.
Military project leader
Leslie Groves led the Manhattan Project, which organized and funded the Trinity test.
Scientific director
J. Robert Oppenheimer directed the Los Alamos scientific work that produced the device tested at Trinity.