NASA

Forty-five years ago today, Christmas Eve 1968, astronauts Frank Borman, James Lovell, and William Anders saw something no human had ever seen before—our planet as it appeared to rise over the moon's horizon.

Their picture of that sight is one of the most iconic images of the 20th century. But they almost missed taking it: The Earth disappears from their view just seconds after they successfully located the color film. Without that picture, the power of that moment, the perspective it conveys, would never have been seen by the billions of humans whom it has touched in the years since.

A new video from NASA weaves together the audio recordings from inside the orbiter with illustrations and modern lunar imagery to tell the story of how that photo came to be, and how it almost didn't.