An astronaut, Major Robert Gaines, is orbiting the Earth in his space capsule.
A significant step in the US Apollo manned lunar missions, Apollo 8 was the first time astronauts orbited the Moon.
Soviet astronauts are now orbiting Earth in Mir, a large module that is seen as the nucleus for a larger space station.
In all, 20 astronauts orbited Earth, 14 traveled to the Moon, and twelve walked upon its surface.
And five American astronauts were safely orbiting 184 miles above the earth, completing a revolution once every 90 minutes.
When astronauts are orbiting hundreds of miles above Earth's surface, they still have to eat, sleep and go to the bathroom.
From 1962 to 1963, Atlas boosters launched the first four American astronauts to orbit the Earth.
Two other astronauts who are featured in In the Shadow of the Moon orbited or looped around the Moon without landing.
During his tenure NASA launched the first seven Apollo missions, in which 20 astronauts orbited the earth, 14 flew to the moon and 4 walked on its surface.
For the next three hours the "astronauts," all in the seventh grade, orbited the earth, launched a satellite and successfully navigated their craft through the difficult descent back to the ground.