The Moon is the nearest body to us in the Solar System, and as a consequence of the Apollo missions is the only extra-terrestrial object that has yet been explored directly by humans. As a consequence of that exploration by both manned and unmanned spacecraft, we now know a great deal about our nearest celestial neighbor.

"I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to the Earth. No single space program in this period will be more impressive to mankind, or more important in the long-range exploration of space; and none will be so difficult or expensive to accomplish." - President John F. Kennedy, to a joint session of Congress, May 25, 1961

". . . t minus 15 seconds; guidance is internal . . . 12 - 11 - 10 - 9 . . . ignition sequence start . . . 6 - 5 - 4 - 3 - 2 - 1 - 0 . . . all engines running . . . Lift-off! We have a lift-off ! . . ." - NASA Mission Control; the launch of Apollo 11 on July 16, 1969

"That's one small step for (a) man. . . one giant leap for mankind." - Apollo 11 commander Neil Armstrong, as he sets foot upon the surface of the Moon; 10:56 PM EDT, July 20, 1969