Forty years ago today, on Dec. 7, 1972, three young men were on their way to the moon, racing away from the Earth at 25,000 miles per hour. Some ways out (about 28,000 miles), their ship passed a narrow tunnel of light, directly between the Earth and the sun. In that moment, they looked out the window and saw the Earth as almost no one had ever seen it: a giant, full, beautiful circle. The sands of the Sahara were in full sunlight. The snows of Antarctica shone bright white. The ocean resonated a deep blue hue.
At that point, one member of the Apollo 17 crew picked up a specially made Hasselblad camera and took several photos. No one knows who did this, because all three astronauts recalled taking the photo. Whomever did, it was a stunning, rare shot. You could see nearly all of Africa – the cradle of humanity – as well as the island of Madagascar, the Arabian peninsula and the clouds swirling over the ocean.
The photo would eventually become known as the “Blue Marble,” and it would become one of the most enduring pictures of all time. In fact, that photo probably changed the way we viewed our place in the cosmos more than any other.