1968 was not a good year on Planet Earth. Though such events can be seen as business as usual in the history of humanity, that year saw more than its share of antiwar and race riots; wars—both cold and hot; and assassinations that ripped the social and political fabric of the U.S. and the world.

In December 1968, Apollo 8 lifted off with the audacious goal of carrying astronauts for the first time in history to another world—the moon. Although they didn't touch down, crewmates Frank Borman, James Lovell, Jr., and William Anders orbited 10 times about 70 miles (110 kilometers) above the primordial lunar surface. For the first time, humans were laying eyes not just on the familiar side that bears the features we see as the "man in the moon," but on our satellite's mysterious far side—only "viewed" heretofore by the cameras of unmanned Soviet and U.S. probes.

Slide Show: The Voyage of Apollo 8

But what really moved the crew, as well as millions of viewers back on Earth, was the awe-inspiring sight of a most familiar place seen from a most unfamiliar perspective: their home world, rising like a serene blue jewel over the tortured horizon of the lunar orb into the inky blackness of the cosmos.

Suddenly, on Christmas Eve, as people across the globe watched a broadcast live from lunar orbit and saw a grainy black-and-white TV image of themselves, all the chaos, enmity and calamity seemed petty, subsumed—if only for a few moments—in a spirit of human unity. Here, reduced to the size of an astronaut's thumb was everything we knew, were and would be riding on a cloud-veiled, water-covered island suspended in a dark, alien void.