Stellune
Synastry is the astrology of relationships. A synastry chart takes two people’s birth charts and lays one over the other, so you can see where one person’s planets fall in the other’s chart and which planets connect.
It’s more detailed than comparing Sun signs, and it’s the method most astrologers use when someone asks “how do we work together?”
How a synastry chart is drawn
Usually your chart sits in the middle, with your planets on the inner wheel, and the other person’s planets are placed around the outside. Lines across the middle show aspects, the angles between one person’s planet and the other’s.
To draw it properly you need both people’s dates of birth, and ideally times and places, so that the houses and rising signs are accurate.
The aspects that matter most
An aspect is the angle between two planets. In synastry, five matter most:
| Aspect | Angle | What it feels like between two people |
|---|---|---|
| Conjunction | 0° | Strong, merged, hard to ignore |
| Trine | 120° | Easy flow, natural understanding |
| Sextile | 60° | Friendly, supportive, takes a little effort |
| Square | 90° | Friction and attraction; growth through challenge |
| Opposition | 180° | Strong pull between opposites; balance needed |
Trines and sextiles feel easy. Squares and oppositions feel charged. Long relationships usually have a mix: ease to rest in and some friction to keep things alive.
Which planet pairs to check first
You don’t need to read every line. These connections carry most of the weight:
- Sun and Moon between you. One person’s Sun touching the other’s Moon is a classic sign of feeling understood.
- Moon with Moon. Whether your emotional rhythms match.
- Venus and Mars. The pull of attraction. Strong links here keep the spark alive.
- Mercury with Mercury. How easily you talk, plan and argue.
- Saturn to personal planets. Saturn contacts often show commitment and staying power, sometimes with a feeling of duty or weight.
House overlays
If you have birth times, synastry also shows where each person’s planets land in the other’s houses. If your Venus falls in your partner’s 7th house (partnership), they may feel you as a natural partner. If your Moon falls in their 4th house (home), being together may feel like home to them.
Reading it as a story, not a score
The trap with synastry is counting good and bad aspects like a match report. A more useful approach:
- Find the two or three strongest links, the closest aspects between personal planets.
- Ask what each one feels like in real life. A Mars square Mars may show up as competitive banter, or as fights over who drives.
- Notice where you already agree and where you already argue. Synastry is best at explaining patterns you’ve lived, not inventing new ones.
Synastry and the Destiny Matrix
Our app pairs the zodiac comparison with the Destiny Matrix, which adds a couple energy from both centre numbers. It’s a different lens: the Matrix describes what the relationship is for, while synastry describes how two people’s energies meet day to day. Together they give a fuller picture. (See Destiny Matrix compatibility.)
Questions people ask
What is the difference between synastry and a composite chart?
Synastry overlays two charts to show how the people interact. A composite chart blends both into a single chart for the relationship itself.
What is the most important aspect in synastry?
Many astrologers look first at Sun–Moon and Venus–Mars connections, and at Moon–Moon for living together.
Are square aspects bad in synastry?
No. Squares bring friction, but also attraction and growth. Relationships with no challenging aspects can feel pleasant but flat.
Can synastry tell me if a relationship will last?
It can show what’s easy and what will take work. Whether a relationship lasts depends on the two people, not on the chart.
Astrology here is for reflection and self-understanding. It doesn't predict events, and it isn't medical, legal or financial advice.