So, 40 years after the Apollo 11 moon landing, here are some of the facts that you probably didn't know about the historic event:
1. Aldrin took secret communion: Before leaving the Apollo 11 moon-landing module, US astronaut Edwin 'Buzz' Aldrin took a Christian Communion, including a wafer and a thimbleful of wine from a kit prepared by his pastor.
Neil Armstrong "watched respectfully, but made no comment to me at the time," Aldrin recalled.
Atheism advocate Madelyn Murray O'Hair, who objected to government employees praying publicly, was suing NASA at the time, so Aldrin kept the act private.
2. Mementos left on Moon: Along with their backpacks, an American flag, and half the Apollo 11 moon-landing module, Armstrong and Aldrin left some sentimental mementos on the surface of the moon, including, a patch from the never-launched Apollo 1 mission, which ended prematurely when flames engulfed the command module during a 1967 training exercise, killing three US astronauts.
The mementos also included medals commemorating pioneering Soviet cosmonauts Vladimir Komarov and Yuri Gagarin, who had died in flight in 1967 and 1968, respectively; goodwill messages from 73 world leaders; and a small gold pin shaped like an olive branch, a symbol of peace.
3. US President had speech ready in case of disaster: President Richard Nixon's speechwriter William Safire wrote a speech in case the Apollo 11 moonwalkers missed the rendezvous with the orbiting command module to return to Earth.
Among the sentiments: "These brave men, Neil Armstrong and Edwin Aldrin, know that there is no hope for their recovery. But, they also know that there is hope for mankind in their sacrifice."
4. Between homecoming and oblivion may have stood a pen: While on the moon, one of the astronauts knocked loose the circuit breaker responsible for igniting the engine that would propel the Apollo 11 astronauts back to the orbiting command module-their only ride home. The interesting fact bout the incident is that Aldrin used a felt tip pen to push the breaker back into place.
5. American flag bit the dust: As the Apollo 11 astronauts blasted off from the moon, flying dust and debris toppled the first American flag planted on the moon.