Forty years ago this week, the crew of Apollo 8 were the first humans to go into orbit around another body besides the earth. The three astronauts, Jim Lovell, Frank Borman and William Anders remembered the mission this week.
The mission was a very big step in the Apollo program. It was the first use of the Saturn 5 rocket for a manned launch. The Saturn was necessary to provide the trans-lunar injection maneuver to fling the spacecraft from earth orbit to lunar orbit. Along with those physical capabilities, there were several orbital navigation tasks that all had to be performed correctly to get the spacecraft to the moon and back.
Apollo 8 also had a large cultural significance. The crew made a television broadcast from lunar orbit and read from the first chapter of Genesis, the bit that begins "In the beginning...". They also took a very famous series of photographs taken, some of which were the "earthrise" photos:
By the way, the Apollo 8 Command module is in the Museum of Science and Industry in Chicago, Illinois.