Synastry: How Two Charts Resonate

What Synastry Means

Synastry overlays two natal charts and looks at the aspects formed between one person’s planets and the other’s. It reveals the patterns of energy exchange between two people.

Its value is not in deciding whether you “can be together,” but in understanding what happens when you are together — which areas come naturally and which call for more communication and tolerance.

Key Synastry Points

• Sun-Moon: a harmonious aspect between one person’s Sun and the other’s Moon reflects mutual nourishment between core identity and emotional needs — an important foundation for a long-term relationship.
• Venus-Mars: the Venus-Mars aspect represents chemistry and attraction. A harmonious aspect brings natural magnetism; a tense aspect brings excitement, but also instability.
• Ascendant-Descendant: the interaction between the Ascendant and the Descendant shapes first impressions and the dynamic of the partnership. The sign on the Descendant describes the qualities you are drawn to in others.
• Saturn-inner planets: aspects between Saturn and the other person’s personal planets bring stability but can also bring pressure. A well-aspected Saturn gives a relationship staying power; a difficult Saturn aspect can make it feel heavy.
• Sun, Moon, Venus and the angles (Ascendant/Descendant/Midheaven/Imum Coeli): personal planets touching the other person’s angles point to a strong connection with tangible, real-world impact.

Harmony and Challenge

Every synastry chart contains both harmonious and tense aspects, and that is normal. A chart that is all harmony is actually rare — and too much harmony can leave a relationship with little room to grow.

What really matters are the core aspects — the interactions between the Sun, Moon, Venus, and Ascendant. If these key points are well connected, the foundation of the relationship is solid; if they are mostly tense, the relationship will call for more understanding and effort.

The Composite Chart and the Nature of the Relationship

Beyond synastry, which examines how the two people’s planets interact, there is also the composite chart — a new chart cast from the midpoints of each person’s corresponding planets. The composite chart describes the qualities of the relationship itself, rather than the interaction between the two individuals.

In the composite chart, the Sun represents the relationship’s core purpose, the Moon its emotional climate, and the Ascendant the face the relationship presents to the outside world. The composite chart is well suited to reading the trajectory of a long-term relationship.

Astralis’s synastry analysis uses both the synastry and composite chart methods, and the AI integrates information from both when interpreting. As one of the specialized readings, synastry analysis is included in the profile unlock report.