A man landed on the moon; a little weekend music festival mushroomed into Woodstock. And a big yellow bird and his fuzzy friends took up residence on a street where the air is always sweet and the sky is always sunny.

The year 1969 was a busy one for big events, and 40 years later, lots of anniversaries are popping up at the intersection of history and pop culture. But when it comes to stirring whirlwinds of memories and before-and-after reflections, the debut of Sesame Street is at the top of the list.

As proof of that status, take this simple test: Try to imagine a world without Muppets.

"I think it's all but impossible to do, but even if you can, what a sadder and drearier world that would have to be," says Michael Davis, author of the best-selling Street Gang: The Complete History of Sesame Street.