It was a fine, clear day in Hiroshima on Aug. 6, 1945. That fact determined the fate of the city, together with its numerous inhabitants.

Given the perfect weather conditions there, a B-29 Superfortress bomber nicknamed the Enola Gay headed for the city, skipping the other two potential targets: the cities of Nagasaki and Kokura, Fukuoka Prefecture.

At 8:15 a.m., the Enola Gay dropped the bomb. Forty-two seconds later, it exploded, its blinding flash as bright as the sun.