On July 20, 1969, Apollo 11 astronaut Neil Armstrong announced his historic arrival on the ancient lava plain of Mare Tranquillitatis with the following message to NASA: "Houston, Tranquility Base here, the Eagle has landed."
Armstrong's words, spoken less than seven hours before he and fellow NASA astronaut Edwin "Buzz" Aldrin took humanity's first steps on the surface of another world, marked a watershed moment in human history. However, the now famous phrase could easily have been uttered from the opposite side of the lunar disk from Tranquility Base.
