The square between Sun and Moon brings together two fundamental drives: Sun's concern with the luminary of vitality, identity, and purpose — the core of the chart around which everything else revolves, and Moon's concern with the luminary of feeling, instinct, and the inner emotional world — the night-light of the chart.
The Nature of the Square
90° — a tense, friction-generating angle that demands resolution through action. The aspect of challenge and growth.
How This Combination Works
When Sun and Moon are in square, their energies cannot be understood in isolation. They interact, modify, and shape each other. Sun's drive is conditioned by Moon's influence, and vice versa. The square describes the quality of this interaction: in dynamic tension, demanding resolution.
The result is a consistent pattern in the native's life — a characteristic way of handling the domains governed by Sun and Moon that reflects the quality of the aspect between them.
In Practice
This aspect shapes how the native express identity and purpose in relation to feel and respond emotionally. When the aspect is harmonious (sextile, trine), the two energies cooperate easily, producing talent and flow. When it is challenging (square, opposition), the two energies conflict, producing tension that must be consciously worked with. When it is a conjunction, the two energies are fused, operating as a single combined force.
The houses occupied by Sun and Moon indicate the areas of life where this pattern expresses itself most consistently.
Further Reading
See the full articles on Sun, Moon, and Square for a deeper understanding of the forces at work in this combination.