The Moon (when it is visible) is the second brightest object in Earth's sky, and, thus, to the ancients represented the second most powerful planet in astrology. The Moon reflects light from the sun, and undergoes a cycle of lunation from full to gibbous to half to crescent to new and back again. The Moon represents an individual's unconscious self.

The Moon was most frequently associated with goddesses rather than gods: Diana, Artemis and Selene were all Moon goddesses.