Synastry Basics: What Does Compatibility Astrology Actually Look At?

By Astrology Tarot AI Editorial · Updated 2026-08-03 · 9 min read

Summary Synastry overlays two birth charts to study aspects and house overlays — attraction, friction and growth themes. Sun-sign match tables are too crude; the Moon, Venus, Mars and 7th house say more about day-to-day rhythm.

Why Sun-Sign Match Tables Fall Short

Social-media compatibility charts usually compare Sun signs only — like judging a whole relationship through "core identity." In real life, the Moon shows emotional response, Venus shows love and values, Mars shows conflict and desire, and the 7th house plus Saturn show commitment and boundaries. Two people with compatible Suns but opposite Moons can still feel exhausting in daily life.

Four Points Synastry Looks At Most

Moon–Moon: Whether emotional languages align and you can soothe each other
Venus–Mars: Spark, chemistry and how intimacy is expressed
Personal planets in the other person's 7th house: Whether you naturally enter a "partner / collaborator" frame
Saturn and Pluto aspects: Long-term commitment, power and transformation themes (read maturely — avoid fear-based takes)

Elements and Modalities: A Quick but Rough Filter

Traditionally, fire with air and earth with water are thought to stimulate each other — one pair leans outward and conceptual, the other toward feeling and structure. This is only a starting point; full synastry still depends on specific planets and aspects. Start with elemental energy to understand your default mode, then notice whether your elements complement or amplify each other.

Synastry Is Not a Verdict on "Meant to Be"

Professional astrology does not treat synastry as a sentence of "doomed to split" or "destined to last." It describes interaction themes: what flows naturally, what needs communication agreements, what keeps reopening old wounds. Hard aspects are not bad relationships — sometimes they are the fuel for shared growth. Easy aspects do not guarantee longevity; they may simply mean less friction and less depth.

Start with a Single Chart

Before comparing two people, clarify your own Sun, Moon and Rising and your 7th house (the one-to-one relationship sector). Astrology Tarot AI's free chart marks your Venus and Mars placements as the base for understanding how you enter relationships.

Method & boundaries · Synastry is based on astronomical calculation of both birth datasets; content is for entertainment and self-exploration only, not relationship or psychological professional advice.