Neil Armstrong and Buzz Aldrin walked on the moon on July 20, 1969, as hundreds of millions of people watched from television sets across the world. It remains one of the most astonishing feat in human history—one that, for a time at least, united a deeply divided country. Fifty years (and leaps and bounds in technological advances) later, it still boggles the mind that humans stepped foot on the moon, thrusting themselves into the unknown where their safety was far from certain. Look, for instance, at the face of Aldrin (below) in the moments before he left the lunar landing module. There's wide-eye wonder, fear, and confidence in his eyes. As all these photos show, it was a stunning human achievement.