Most astrologers seem to agree in hailing the sun as the single most important planetary body in astrology, at least for the conscious part of the human psyche. It is known as the "greater light" (the moon is the lesser) since it represents that irreversible flow of seasonal energy that allows the continuation and development of all forms of organic life. Likewise in astrology the sun becomes the irreversible flow of spiritual energy that molds individual consciousness. It is the life-giver, the source of light closely associated with greek mythological god Apollo. Apollo was the provider of light and life, but also distributor of illness and sudden death through the heat of the sun. Thus, in the context of astrology the sun is connected to life-force and vitality, affecting the status of both the physical and mental organisms. The astrological sun represents pure being, and the courage of being just for the sake of being; not for doing or accomplishing anything in particular.
In the natal (birth) horoscope, the sun is the force that integrates all other factors and energies into a focused will or individuality. That will is of course more or less focused, and that individuality more or less pronounced, dominant and uniform. This is determined by the zodiac sign and house position of the sun, and not least the aspects it receives from other planets. The placement of the sun gives an expression or color of the self that will always dominate that person's awareness. A part of the psyche that someone always will have to return to, that she is dependent on. One that is given space and is exhibited, perhaps with pride. Since it represents active consciousness, the sun marks the "yang" part of the personality in both male and female horoscopes. It is the source of energy, while the moon - considered the traditional "yin" part - is the container and responding instrument of this energy; a more unconscious mirror and distributor. The sun is for better or worse the "hero" of the planets, its image being of power and natural authority. Important is also its symbolizing of fatherhood and "fatherly" energies.
The moon is the channel for most everything that cannot be expressed by the conscious energy of the sun. Much like a solar energy generator that is dependent on the sun, yet becomes that which gives meaning and usefulness to its powerful radiance. Its archetype is that of the great mother, the womb of life, receptive passivity, inwardness and fluid changeability. This terminology may seem outdated in a progressive modern society, but it hardly matters since the moon is of equal power and importance in male and female horoscopes. Even if its symbolism springs from male-dominated, socially patterned conceptions of femininity, the moon's actual influence on the individual knows no genderly boundaries. It has a significance that is more collective and spontaneous and less individualistic and intellectual than that of the sun. If the sun relates to center, the moon relates to periphery - but also to depth. Its astrological image is similar to the idea of "soul" or a soul.
In the horoscope, the moon is the primary indicator of needs. In particular emotional needs. The zodiac sign, aspects and house position of the moon tells us the "matter" of what an individual needs, that is the type of qualities, behaviour and sorts of activity that (often unconsciously) are psychologically important and central to them. The moon shows how we get along with people and how we relate. Some astrologers consider it to be an indicator of public behaviour and spontaneous reactive patterns, an idea that appears to bring it closer to the Ascendant. What seems clear is that the moon represents less conscious and out-in-the-open levels of character, and the area in which it falls shows an instinctive, auto-pilot, inherited quality. It remains in some kind of opposition to the energy of the sun - the moon part of the personality is the "other side", the subjective reaction to the "objective" expression, or the complementing side. The idea of the moon brings a fragmentation that truthfully constrast the appearant unity of the sun's image and expression.