What invisible bonds connect your charts?
Calculate the synastry between two birth charts and discover the planetary aspects shaping your connection.
Synastry overlays two birth charts to reveal compatibility, challenges, and the cosmic blueprint of your relationship. Enter your birth data and your partner's to see how your planets align.
164 bonds mapped this week
Map Our Bond
“His Mars sits exactly on my Venus. The reading explained why we fight about the same three things and why the chemistry hasn’t faded in seven years. Finally have language for what we already knew.” — ♎ LIBRA SUN · COSMIC BOND READING
“Didn’t expect the Bazi compatibility layer to be the part I quoted back at her. My Earth Day Master and her Wood Day Master have been in a quiet tug-of-war the whole time — that’s every Sunday argument we’ve ever had, named.” — ♑ VIRGO SUN · COSMIC BOND READING
“We’d been stuck on whether to move in together. The reading named my Saturn conjunct her Moon as the pattern — and gave us the exact conversation we needed to have. We moved in three weeks later.” — ♋ GEMINI SUN · COSMIC BOND READING
Person A
Person B
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Your Cosmic Connection
The Cosmic Bond — Compatibility Reading
This free calculation shows Sun, Moon, and Ascendant compatibility. The full reading goes deeper into all six systems: Western Astrology, Chinese Bazi, Sabian Symbols, Tree of Life, Hermetic Alchemy, and Hermetic Virtues.
Explore your individual charts in all six systems:
Launch Your Birth Chart Explorer →Synastry maps the bond. The Athanor answers the question between you.
A compatibility report describes the dynamic. The Athanor takes one specific question about the relationship and answers through your chart cross-referenced — six esoteric traditions converging on what the bond is actually asking of you right now. Three questions, $5.
Ask the Oracle →What is Synastry?
The Art of Comparing Birth Charts
Synastry is the practice of overlaying two birth charts to analyze the relationship between them. Rather than creating a new chart, synastry preserves both charts and examines how the planets in one person's chart interact with the planets in another's. This reveals the invisible threads connecting you — the harmonies, the friction, and the dance between your cosmic blueprints.
The Five Major Aspects
Aspects are the angles between planets. In synastry, five major aspects reveal the nature of connection: Conjunction (☌) shows fusion and merging of energies; Sextile (⚹) represents easy flow and natural support; Trine (△) indicates effortless harmony; Square (□) reveals productive tension requiring effort; and Opposition (☍) shows complementary forces that attract and challenge simultaneously. Harmonious aspects (trine, sextile) feel easy; dynamic aspects (square, opposition) demand growth.
Synastry vs. Composite Charts
Synastry compares two charts directly, showing how each person's planets affect the other. A composite chart, by contrast, averages the two birth times to create a single new chart representing the relationship as an independent entity. Synastry is about interaction; composite charts show the relationship's distinct personality.
Sun, Moon, and Ascendant in Compatibility
The Sun represents core identity and willpower; the Moon represents emotional nature and instinctive response; the Ascendant represents outward presentation and first impression. In synastry, these three points matter most. Sun-Sun aspects show identity resonance; Sun-Moon aspects show emotional-spiritual connection; Moon-Moon aspects reveal emotional compatibility. The Ascendant's role is subtler—it shapes how each person perceives and is perceived by the other.