From CNN:
Forty years ago this week, three men in a tiny spacecraft slipped their earthly bonds and traveled where no one else had before, circling the moon 10 times and bringing back an iconic image of a blue-and-white Earth in the distance, solitary but bound as one against the black vastness beyond.

The voyage of Apollo 8 from December 21-27, 1968, marked humans' first venture to another heavenly body.

Apollo 8 astronauts remember historic voyage - CNN.com