The Moon is directly illuminated by the Sun, and the cyclically varying viewing conditions cause the lunar phases.
The image of the Moon here is drawn as is normally shown on maps, that is with north on top and west to the left.
The two hemispheres have distinctly different appearances, with the near side covered in multiple, large maria (Latin for 'seas').
These lowlands were believed to be seas of lunar water by the astronomers who first mapped them, in the 17th century (notably, Giovanni Battista Riccioli and Francesco Maria Grimaldi).
[3] These larger impact craters make up the Man in the Moon references from popular mythology.