This is one of the most reproduced photographs in history. It was taken by the crew of Apollo 17 on their way to the Moon, from roughly 29,000 kilometres away. The Sun was behind the astronauts, so the whole planet appears fully lit — a complete, glowing marble.

You can see Africa, the Arabian Peninsula, the Mediterranean, and the Antarctic ice cap, under a tangle of white weather systems.

Apollo 17 was the last crewed mission to the Moon. No human since 1972 has been far enough from Earth to see the whole planet like this with their own eyes. Every "whole Earth" photo since has been taken by robots, or stitched together from satellites.

Hang it in your mind next to Earthrise. Together they mark the moment we saw where we live.