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Relationship astrology

Composite charts vs synastry: what is the difference?

Synastry compares two existing charts; a midpoint composite creates a derived chart used to symbolize the relationship as a shared pattern.Reviewed · 2026-08-24 · Educational astrology content
Direct answer

Synastry studies cross-chart contacts between two people. A midpoint composite calculates mathematical midpoints between corresponding planets and angles to form a derived chart. They answer different questions and should not be treated as interchangeable evidence.

Key points

  • The composite chart is calculated, not a sky chart for the relationship’s first meeting.
  • Accurate birth times matter for composite angles and houses.
  • Synastry can show directional impact; composite interpretation is shared.
  • An event or Davison chart uses a different construction.

Method

  1. Interpret both natal charts first.
  2. Review synastry for interaction patterns.
  3. Use the composite to examine recurring shared themes.

Limits and responsible use

  • A composite chart cannot guarantee relationship duration.
  • Derived angles are unreliable when either birth time is unknown.