LOS ANGELES (AP) ― Musical moments that capture the attention of a national audience ― and beyond ― never seem to be in short supply. Last week, Bruno Mars set a ratings record with 115 million people watching his Super Bowl performance. A few months ago, the talk was about Beyonce’s surprise album. And there’s still discussion of That Miley Moment at the MTV Video Music Awards.

But moments that spark a musical revolution? A dramatic altering of the pop culture landscape? A true moment for historians to analyze? Rare indeed, which is what makes the 50th anniversary of what is considered the start of Beatlemania so remarkable ― and so unlikely to happen again.

“The media has gotten so fragmented now ... there’s 50 things in a marketing plan for an artist today,” said Revolt TV President (and former MTV executive) Andy Schuon. “The ability to fan that fire and to give it the kind of intensity that ‘The Ed Sullivan Show’ could get doesn’t exist today.”

Sunday marks the 50th anniversary of the Beatles’ performance on “Ed Sullivan,” their first appearance in America. Nielsen says 45 percent of all TV sets in use at the time were tuned into the broadcast, with fans and the uninitiated alike gathered shoulder to shoulder in their living rooms. The Beatles landed on a trigger point when they hit America. It was a pop culture sonic boom spurred by talent, timing and luck that’s still rattling the windows.

“This was a seismic shift in American culture and it gave the teenagers not only a voice but a way of being, a way of thinking that had never occurred before,” Beatles biographer Bob Spitz said.

“Previous to the Beatles’ arrival here, teenagers were an appendage in the family. After that, the teenager became one of the dominant forces in the family. They became a marketable force and that didn’t happen with Elvis. This was pure.”

Grammy Awards producer Ken Ehrlich, who produced this Sunday’s TV special “The Night That Changed America: A Grammy Salute to The Beatles” on CBS, vividly remembers the electricity surrounding the British band’s appearance as he gathered with friends at a boarding house in Athens, Ohio, near the Ohio University campus to watch the show.

Fans’ interest had been stoked expertly thanks to their recent hits, including “I Want to Hold Your Hand,” and a promotional campaign that included mop-top wigs.

“Everybody was waiting for it,” Ehrlich said. “People hadn’t seen them. There weren’t VCRs, there weren’t DVRs. There was nothing. If you didn’t see it on one of three TV channels, you didn’t see it.”

A generation of baby boomers ― teenagers just turning 13 and 14 ― was poised for the moment: The relatively new medium of TV, the growing media culture in the U.S. and a burgeoning post-war affluence that allowed millions of teens to bond through the black-and-white broadcast that began with a mop-top shaking version of “All My Loving.”

“Entire families wanted to see what was going on here because the phenomenon of The Beatles arriving here was so spectacular, so different from anything we’d ever experienced before, and everybody wanted to look at it,” Spitz said. “The kids wanted to look at it because they wanted to be like The Beatles and the parents watched it because they wanted to see what they were up against. Really.