Some interesting things happened in history on this date.
Neil Armstrong was born.
In 1945, the first atomic bomb was loaded on the Enola Gay on a B 29 Super Fortress. This is why it is Japan's lucky day.
It seems counterintuitive, but follow me. There were other options to using atomic weapons. First, invasion. The Emperor himself hoped to win a battle, or at least make it bloody enough, that Japan would be in a better position to negotiate. Neither would happen. American air power, unopposed at the time, would destroy Japanese armor, artillery, and any massed infantry divisions. Nor were the Americans interested in negotiations.
Another option was attacking agriculture. Japanese rice production is very intricate and delicate. They made an admirable effort to switch to wheat, which would be vulnerable to fire bombing. The merchant fleet and fishing fleet had been sunk. Most of the trains had been wrecked, and Japan did not have the infrastructure to use trucks. Wait a few months, and step on the islands with no shots fired. The Japanese will have starved.
In both cases, we are looking at the end of the Japanese people.
The late and very lamented Iris Chang described Japanese culture as "vulnerable." We could argue that, I suppose, but is also vibrant .
If the US had not used atomic weapons, the world would be poorer.