A photograph of Earth taken by an astronaut orbiting the Moon on Christmas Eve, 1968. The three Apollo 8 astronauts were the first humans to ever leave Earth orbit.
In this image, light from the Sun partially illuminates Earth. Earth is partially darkened just as the Moon appears partially darkened to Earth observers during many of its phases.
Courtesy of the Apollo 8 crew and NASA. www.nasa.gov/multimedia/imagegallery/image_feature_102.html. Public Domain.