Apollo 8’s closest approach to the Moon was 69 miles (about 111 kilometers). The spacecraft reached this altitude during its first lunar orbit on December 24, 1968, becoming the first crewed mission to orbit another world.
Apollo 8 was not designed to land. Its crew—Frank Borman, James Lovell, and William Anders—spent roughly 20 hours circling the Moon, completing ten orbits before firing the spacecraft’s engine to return to Earth.
The 69-mile figure is an altitude above the lunar surface, not the total distance traveled and not the distance from Earth. It is also sometimes expressed as approximately 60 nautical miles or 110 kilometers, which can create slightly different-looking answers.
The mission’s close lunar orbit allowed the crew to photograph potential Apollo landing sites and capture the famous Earthrise image. Apollo 10 later conducted a much lower lunar-orbiting rehearsal before Apollo 11’s landing.