[Read all Times reporting on the 50th anniversary of the Apollo 11 moon landing. | Sign up for the weekly Science Times email.]

The moon is at once so close and so far.

Neil Armstrong’s photograph of Buzz Aldrin on the lunar surface remains one of the most recognizable and enduring images in history, in part because so few people have been to the place where that picture was taken. The privilege of taking steps on our closest heavenly neighbor belongs (so far) to a tiny, exclusive cohort of a dozen individuals.

The two astronauts spent just over 20 hours on the moon, after three days of space travel and years of preparation, planning and practice. And then they came back, having forever expanded the way humankind sees itself. Five decades later the moon landing, as achievement and notion, remains mind-boggling.