On Dec. 19,1972, a final sonic boom above the South Pacific signaled the end of the Apollo program, as a tiny space capsule burst back through the blue sky. On board were the last three astronauts to visit the moon on Apollo 17. Riding home with them was the precious negative of a photograph that would go on to become the most reproduced image in human history.
Frame No. 22725 in magazine NN was a single shot of the whole Earth — later branded "the Blue Marble." Snapped 12 days earlier by astronaut-geologist Harrison Schmitt as the spacecraft accelerated away from the Earth, the picture was immediately captivating.
Journeying southward, toward the moon, Schmitt had seen his home planet upside down, with the continent of Antarctica sprawling over the top. Below it the entire African land mass arced downward toward the cradle of civilization in the Middle East, with the edge of southern Europe right at the bottom. On a rare, relatively cloudless day, so many human histories, causes and stories were on show in one view.