Apollo 11 astronauts (from left) Neil Armstrong, Michael Collins, and Edwin "Buzz" Aldrin prior to the historic mission that saw Armstrong and Aldrin, on Sunday, July 20, 1969, became the first humans to set foot on the moon. In celebration of the 40th anniversary of the lunar landing, Buzz Aldrin spoke to LIFE about the mission, his colleagues, and what it felt like to gaze back at Earth, a quarter-million miles away, shining quietly in space.