In the birth chart, the Moon is second in importance only to the Sun. Unlike the other planets the Moon orbits the earth, and seen from the earth is the same size as the Sun (hence the possibility of total eclipses). The Moon gives off no light of its own, however, but reflects and polarises the light of the Sun.

The Moon represents memories, feelings and instinctive responses that lie just below the level of consciousness. As the Moon orbits the earth, it generates the movements of the tides and governs other natural cycles, such as the menstrual cycle in women. The Moon therefore symbolises the ebb and flow of feeling and emotion (symbolised by water in Astrology), and the feminine principle in nature and in the individual.

The Moon's sign position and aspects to the Moon show how we react instinctively, and what we need to feel comfortable and secure. As children the Moon is the Mother, or at least how we experienced our mother. As we grow older this extends to our relationships with women in general (particularly for men), and our instinctive or conditioned responses to the world in general; based on the often unconscious memories of this early nurturing experience (or lack of it).