It was many years ago when I first had this moment. Someone I knew, I realized, had been born after Star Wars had come out. He had never lived in a world that didn't have Star Wars indelibly stamped upon its culture. The idea that the movie was once something that people figured wouldn't even succeed or make a profit. let alone become iconic, was alien to him.
As time goes by, different events serve as that boundary point of my advancing age: something which is an event to me, but "merely" a part of history to someone else. For my parents' generation, it was the moon landing, or JFK's assassination. For their parents it was Pearl Harbor, or D-Day, or VJ-Day. After Star Wars the next one for me is probably the fall of the Berlin Wall -- that one's coming up hard now -- or the Challenger disaster. It will be 9/11 all too soon.