"It's going to be a very small picture, but we're all going to be in it. All trillions of us on Earth."

"It's not our first group portrait, but Carolyn Porco, the woman in charge, says it's going to be gasp-worthy. She should know. She helped shoot some of the early ones."

"What am I talking about?"

"Well, going back a bit, here's the first one, the granddaddy of Earth pictures. It's often called the 'Blue Marble' shot, and it was our first look at our whole planet suspended in space, taken in 1972 as the Apollo 17 crew headed toward the moon. It makes us look dazzlingly blue — and quite alone."