The date was August 6, 1945, and the clock read 8:00 AM (Hiroshima time) when the B-29 Superfortress Enola Gay entered Hiroshima airspace. The plane was piloted by 29-year-old Lt. Colonel Paul Tibbets. Three weeks ago he had been in the New Mexico desert to witness the first ever detonation of an atomic bomb. Now he was piloting a uranium bomb on a mission that he and everyone else in the plane with him hoped would bring the Second World War to an abrupt end.

At 8:05 AM, flight navigator Dutch Van Kirk shouts over the comlink: "Ten minutes to the AP [aiming point]!" Seven minutes later, control of the aircraft is handed over to bombardier Thomas Ferebee, as the bomb run begins. At around this same time, Radio Hiroshima reports that three American aircraft had been spotted over Hiroshima airspace. Not much could be done about it, however, as all three planes are Superfortresses flying at a cruising altitude of 31,500 feet. At this point in the war, Japan had no countermeasures against planes flying so high in the sky. Aside from the Enola Gay, one Superfortress (Great Artiste) is there to take scientific measurements while the other (Necessary Evil) is there to record video and photographic documentation of the event. At 8:12 AM, Tibbets tells the crew: "On glasses." Even from the relative safe distance the Enola Gay should be when detonation occurs, the magnitude of the flash would still be enough to cause at least temporary blindness.

At 8:14 AM, Ferebee's aiming point - the T-shaped Aioi Bridge - is now in clear view. The 60 second sequence to automatic release is engaged via the Norden bombsight. At the same time, Luis Alvarez - a researcher on the Manhattan Project - drops two pressure gauges from Great Artiste via parachute to determine the bomb's yield. Observers within Hiroshima some six miles below the aircraft remember seeing these devices as they floated slowly toward the ground.

It is now 8:15 AM and the Enola Gay is flying at an altitude of 31,050 feet when its bomb bay doors snap open. Almost immediately, the atomic bomb known as Little Boy detaches from the bomb bay and begins its descent toward Hiroshima. Ferebee shouts: "BOMB AWAY!" Tibbets immediately takes back control of the aircraft and pulls it into a sharp 155 degree turn to the right in an effort to get clear of the city before detonation.

After falling for 43 seconds, the time and barometric triggers started the firing mechanism: a uranium bullet fired down a barrel into a uranium target. Together they started a nuclear chain reaction. Solid matter began to come apart, releasing untold quantities of energy. At 8:16:02 AM, Hiroshima time, Little Boy detonated at an altitude of 1,968 feet above the Dr. Shima's Clinic - some 550 feet away from the aiming point of Aioi Bridge. A tenth of a second after detonation, the fireball has expanded to a diameter of 100 feet and reaches a peak temperature of 500,000 degrees Fahrenheit. Some .15 seconds after detonation, the super heated air above ground zero glows and a woman sitting on the steps of the bank of the Ota River a half mile away is instantly vaporized.

Within three tenths of a second after detonation, intense infrared energy is released and burns exposed skin for miles in every direction. Roofing tiles fuse together, a bronze Buddha statue melts, along with granite stones. The soft internal organs of humans and animals evaporate as the blast wave propagates outwards at speeds exceeding 7,200 MPH. Approximately one second after the initial blast, the fireball reaches its maximum size of 900 feet in diameter and the blast waves slows to a speed of some 768 MPH. The temperature at ground level directly below the blast has now cooled to around 7,000 degrees Fahrenheit. The blast wave spreads fire outward in all directions at 984 MPH, tearing and scorching the clothing off every person in its path. The blast wave hits the mountains surrounding Hiroshima and rebounds back. Approximately 60,000 out of the city's 90,000 buildings are demolished by the intense wind and firestorm.

Approximately 525 feet southwest from the hypocenter, the copper cladding covering the dome of the Industrial Products Display Hall is gone, exposing the skeleton-like girder structure of the dome. However, most of the brick and stonework of the building remains in place. The ground within the hypocenter cools to 5,400 degrees Fahrenheit as the mushroom cloud reaches a height of approximately 2,500 feet. Shards of glass from shattered windows are embedded everywhere, even in concrete walls. The fireball begins to dim but still retains a luminosity equivalent to ten times that of the sun at a distance of 5.5 miles.

Nuclear shadows appeared for the first time as a result of the extreme thermal radiation. These shadows were outlines of humans and objects that blocked the thermal radiation. Examples are the woman who was sitting on the stairs near the bank of the Ota River. Only the shadow of where she sat remained in the concrete. The shadow of a man pulling a cart across the street is all that remained in the asphalt. The shadow of a steel valve wheel appeared on a concrete wall directly behind it because the thermal radiation was blocked by the outline of the wheel.

The firestorm continued to rage within an area which had now grown to over a mile wide. A gruesome, raging red and purple mass begins to rise in the sky. The mushroom column sucks superheated air, which sets fire to everything combustible. A coded message is sent to General Thomas Farrell at Tinian. It stated: “Clear cut, successful in all aspects. Visible effects greater than Alamogordo. Conditions normal in airplane following delivery. Proceeding to base."

The Enola Gay circled Hiroshima a total of three times beginning at 29,200 feet and climbing towards 30,000 feet before heading for home. It was 368 miles from Hiroshima before Caron reported that the mushroom cloud was no longer visible.

The "mushroom cloud" rising above Hiroshima - photograph taken by the B-29 Superfortress Necessary Evil (August 6, 1945)

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