Little Boy was the code name of the atomic bomb which was dropped on Hiroshima, on August 6, 1945 by the 12-man crew of the B-29 Superfortress Enola Gay, piloted by Colonel Paul Tibbets of the United States of America Army Air Forces. It was the first atomic bomb ever used as a weapon and was dropped three days before the "Fat Man" bomb was used against Nagasaki.
The weapon was developed during the Manhattan Project during World War II. It derived its explosive power from the nuclear fissioning of enriched uranium. The Hiroshima bombing was the second man-made nuclear explosion in history (the first was the "Trinity" test), and it was the first uranium-based detonation ever. Approximately 600 milligrams of mass were converted into energy. It exploded with a destructive power equivalent to between 13 and 16 kilotons of TNT (estimates vary) and killed approximately 140,000 people including associated effects.
