Today marks the 45th anniversary of Apollo 11's launch. If your history is fuzzy, that's the mission that took astronauts Buzz Aldrin and Neil Armstrong to the moon. Aldrin says he was "out of town" on July 20, 1969, and missed the world's celebration of their lunar landing, and now he wants to know where everyone was that Sunday when he and Armstrong set foot on the moon.
He's set up a YouTube channel inviting celebrities and ordinary people to share their memories of that day.
Among those reminiscing via social media: actors Tom Hanks and Tim Allen, and London's mayor, Boris Johnson.
It's the first big anniversary of man's first moon landing without Armstrong. He died in 2012 at age 82.
Aldrin and Michael Collins, the command module pilot, will take part in a NASA ceremony at Florida's Kennedy Space Center on Monday. Armstrong's name will be added to the historic Operations and Checkout Building.