"How cool," said astronaut Julie Payette, who was 5-years-old when Armstrong and Aldrin touched the moon's surface July 20, 1969.
At the White House Monday, President Barack Obama met with the Apollo 11 crew, telling them they untethered humans from planet Earth to explore the stars.
"Very rarely do I have such an extraordinary pleasure as I have today to welcome three iconic figures, three genuine American heroes," Obama said.
On that historic day 40 years ago, Armstrong reached the surface first and soon was joined by Aldrin, the two men spending 21 hours on the moon as astronaut Michael Collins remained in orbit, piloting the spacecraft that would return the three of them to earth.
While on the moon, Armstrong and Aldrin planted a U.S. flag and left a sign reading, "Here men from the planet Earth first set foot upon the moon July 1969, A.D. We came in peace for all mankind."