On the technical side, Apollo 8 was mainly a test flight for the Saturn V and the Apollo spacecraft. The main spacecraft system that needed testing on a real lunar flight was the onboard navigation system.

In a small spacecraft, it was hard for the other two guys to sleep when the on-duty man was talking to Mission Control regularly.

Speaking of photography, while the Apollo 8 crew shot hundreds of photos, there was one that got everybody's attention: a blue-and-white Earth rising over a gray moonscape.

Henry Spencer Quotes