July 16, 1945: Trinity, the first nuclear test. In this photo, the nuclear age is only a few milliseconds old. About ten milliseconds after this photo was taken, the fireball was about 300% larger; after ten seconds, it was beginning to form a mushroom cloud. The black spots indicate where the brightness of the explosion burned through the negative.
Photo by Berlyn Brixner. National Archives Still Pictures Branch, 454-RF-12A (TR84-1).