On December 7, 1972, the Apollo 17 crew photographed the “Blue Marble” above, the first photograph in which Earth is in full view. The image is one of the few to show a fully illuminated Earth. This view of the Earth is credited with helping humans realize the fragility of their home. A couple years earlier, on December 24, 1968, the Apollo 8 crew photographed the iconic “Earthrise” photo of the Earth rising from the horizon of the moon.
Other iconic images of the earth can be found here.