While sun sign compatibility provides a useful overview, professional astrologers emphasize that a complete compatibility reading requires examining the full natal chart of both individuals. The natal chart is a map of the sky at the exact moment and location of your birth, and it includes placements for the Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto across the twelve zodiac signs and twelve houses.
The Moon sign is arguably the most important factor in emotional compatibility. It governs your inner emotional world, your instinctive reactions, and what you need to feel safe and nurtured in a relationship. Two people with compatible Moon signs often feel an immediate emotional connection, even if their Sun signs suggest challenges. Venus, the planet of love and beauty, reveals how you express affection, what you find attractive, and your approach to romance and partnership. Mars, the planet of desire and drive, indicates how you pursue what you want, your sexual energy, and how you handle conflict.
In synastry — the branch of astrology dedicated to relationship analysis — astrologers examine how the planets in one person's chart interact with the planets in another person's chart. Key aspects to look for include conjunctions (planets in the same sign), trines (planets four signs apart, considered harmonious), sextiles (planets two signs apart, also positive), squares (planets three signs apart, indicating tension), and oppositions (planets six signs apart, creating polarity). A relationship with multiple trines and sextiles tends to feel easy and supportive, while one with many squares and oppositions may be more challenging but also more transformative.
Another advanced technique is composite chart analysis, which creates a single chart representing the relationship itself by calculating the midpoints between each pair of corresponding planets. This composite chart reveals the purpose, themes, and potential of the relationship as its own entity. Together, synastry and composite analysis provide a comprehensive astrological understanding of any partnership — far beyond what sun sign compatibility alone can offer.
