August 6, 1945 at 8:15 a.m.

The US dropped the atomic bomb on Hiroshima on August 6, 1945 at 8:15 a.m.  The bomb detonated 600 meters above the city center.

 The entire city was leveled. and thousands of people died.  Many who survived had physical and psychological damage.  At the instant the bomb denoted the temperature at the center exceeded one million degrees celsius generating an enormous fireball. Within 1 second of detonation, it had extended to its maximum diameter of 280 meters.  The blast pressure was 500  meters from the center.  Buildings were crushed, people were blown through the air. The heat rays and blast burned and crushed nearly all buildings within a 2 km of the hypocenter. Many junior high school boys and girls had been helping to demolish buildings to make room for new fire lanes.  Most of those children were never identified except for their belongings left behind at worksites. The Motoyasu River was full of  dead people. The nuclear radiation caused severe injuries to the human body.  It affected all those within 1 km of the hypocenter.  Many people died within a few days. The Atomic Bomb Dome was built in 1915 by a czech architect and was formerly the Industrial Promotion Hall. The bomb exploded directly above the Atomic Bomb Dome and everyone inside was killed.  It is one of a few buildings that were left standing near the epicentre.  After the war there a was a discussion to preserve the shell as a memorial

At the Hiroshima Peace Memorial Museum, you can see a collection of belongings left by victims, photos and other things that convey the horror of this event. Most of the belongings on display were found by family members who went searching for their missing family.
One thing that hit me was a tricycle.  It belonged to Shinichi Tetsutani who was 3 years old.  He was riding in front of his home on the morning of August 6.  He was badly burned and died later that night.  His father buried the tricycle and his son in the backyard because he thought his son was too young to be buried in a grave far from home.  In 1985 the father dug up Shinichi's remains and the tricycle.  He transferred the remains to a family grave and donated the tricycle to the museum.

You can also see Hiroshima before the bomb. The atomic bomb was 3 meters long and weighed 4 tons.  It carried about 50 kg of uranium.