Sun-Moon synastry contacts naturally complement one another on the birth chart and form complementary parts of a personality. In a relationship, it works this way too, and the Sun’s self-expression, creativity, and sense of purpose meet with the Moon’s emotional, tender, and nurturing reactions. So the Moon essentially supports the Sun’s development and who they are becoming. With the easy contacts (sextile, trine, and the conjunction), the Moon bathes in the warmth of the Sun and feels reflective, contemplative, warmed in their presence. Both illuminate each other. In this interaction, the Moon feels safe expressing their vulnerable side, and is understanding, comforting, and plays an emotionally supportive role in the relationship. The Sun has finally found someone who can be there as a safe container for their growth and continuing progress as an individual. Ultimately, the Sun and Moon is a fire and water mix, and this pairing, when found across two charts, essentially creates a warm, supportive, and generous interaction.
According to Lyn Birkbeck:
Whatever your sexes, ages or positions in life, this interaction gives a definite feeling of being connected in some way, if not in many ways. There is a feeling of familiarity, despite anything else that might or might not be happening between you both. It is as if one of you, the Sun, has the other one, the Moon, fixed in their beam, as if they are illuminating their inner emotional being. Depending on other factors, particularly sexual or status ones, this can make the Moon feel overwhelmed and greatly impressed, as somehow inferior or even at the Sun’s command. At another level – when there are plenty of strong interaction – you may feel like soul-mates.
It’s obvious to see why astrologers dub the Sun and Moon conjunction the “Soul Mate” aspect. On some level, if someone is attuned, familiar and at ease (Moon) with who you are as a person (Sun), it is understandable to think this is “the one.” When the conscious goals of the Sun person are in tune with the unconsciousness expression of the Moon, it creates a powerful feeling of emotional togetherness. With the Sun and Moon conjunct, there is a common and similar approach to life, and the way one person moves forward in life the other person has kind of been there before and understands. The Moon person is always the reactive one in the partnership and the Sun person is the pro-active one. So while the sense of purpose of the Sun is keenly felt, it is the Moon who feeds the Sun’s creativity and direction in life. When the Sun and Moon are sextile or trine to one another, it is the Sun person who lights the way, and the Moon person supports and nourishes the Sun’s aims, goals, and objectives.
When the Sun and Moon are opposed or square to one another, the Sun’s goals in life are challenged by the security needs of the Moon. The Sun and Moon are two of the most powerful personality factors in the chart, but the past conditioning of the Moon may struggle to support the self-expression of the Sun. The solar individual may see the lunar individual as over-emotional, dependent, and sensitive. With the hard aspects, they tend to operate at times harmoniously and then fall into disharmony. There will be some times of friction, which can be handled if you can understand where the Moon is coming from and honor the individuality and purpose of the Sun. The trouble is that the Sun person cannot feel where the Moon is coming from and the Moon cannot see where the Sun is heading. It may be as simple as two temperaments clashing and not necessarily that one will not support the other in this relationship.
Carl Jung, as part of his life-long interest in astrology, researched five hundred married couples, using their birth charts to test the classic aspects. He found a significant proportion had Sun conjunct Moon, Moon conjunct Moon, and Moon conjunct Ascendant, and reported his findings in the monograph, Synchronicity – An Acausal Connecting Principle. However, I read somewhere about the discrepancies of the study, and only the conjunction and opposition were used. The planets and points used in the study were the Ascendant, Sun, Moon, Venus, and Mars. Jung said these two aspects (Sun-Moon & Moon-Moon) have long been mentioned in the old traditional literature, as marriage characteristics and they, therefore, represent the oldest tradition.
In some of the older textbooks when the Moon belonged to the woman and the Sun belonged to the man and both were in conjunction or harmonious aspect, it was said that the female would make the best of wives. While the male with the Moon would make the most domesticated of husbands, meekly submitting to the wife’s beck and call. Whatever the truth, both male and female roles come into play whoever holds what position. In the olden days, the woman supported the male and naturally played the home-maker and domesticated partner anyway. Today, though, most people try to live out the best of both worlds. Hence, this synastry pairing is very much like the Union of Opposites: In alchemical terms, this is called the conjuctio. The inner marriage is the union between opposites: yin and yang, masculine and feminine, spirit and soul, or heaven and earth. This is the powerful place of centre which can hold the opposite or dual forces of life and the human quest for union.