Earthrise

Coming round the far side for the fourth time, Apollo 8's crew looked up and found the Earth climbing over the lunar horizon, and scrambled for colour film.

The photograph was not on the flight plan and the moment is on the onboard tape, Anders shouting for a magazine while Borman and Lovell argue about which window. It is often credited with starting the environmental movement, on the grounds that nobody had ever seen the whole thing at once before.