Here's a bit more about the circumstances of that photo (from the Guardian website):
Anders recounted the experience as part of a BBC documentary on the mission.
“We’d been going backwards and upside down, didn’t really see the Earth or the sun, and when we rolled around and came around and saw the first Earthrise,” he said. “That certainly was, by far, the most impressive thing. To see this very delicate, colorful orb, which to me looked like a Christmas tree ornament coming up over this very stark, ugly lunar landscape really contrasted.”
“I don’t know who said it, maybe all of us said: ‘Oh my God. Look at that!’” Anders said.
“And up came the Earth. We had had no discussion on the ground, no briefing, no instructions on what to do. I jokingly said, ‘Well, it’s not on the flight plan,’ and the other two guys were yelling at me to give them cameras. I had the only color camera with a long lens. So I floated a black-and-white over to Borman. I can’t remember what Lovell got. They were all yelling for cameras and we started snapping away.”
