Ethan and I have been together for six years. We've been married for four. We've survived a cross-country move, a pandemic, a dog with anxiety, and the kind of fights that make you wonder if you even speak the same language.
I could tell you our synastry chart is "perfect." It's not.
I could tell you it's "challenging." That's also not quite right.
The truth is somewhere in between: our charts don't tell us whether we should be together. They tell us what we signed up for.
And that's the thing about synastry—the art of comparing two birth charts. Most of what you'll find online treats it like a cosmic compatibility quiz. "Soulmates or disaster?" "Is your Venus in harmony?" "Will you survive Mercury retrograde together?"
That's not how it works. That's not even close to how it works.
Let me show you what to actually look at—so you can use synastry as a tool for understanding, not for judging.
First: what synastry is not
Before we get into the planets, I need to clear up some myths.
Synastry is not a compatibility score. It doesn't tell you if you're "meant to be" or "doomed." There's no such thing as a perfect synastry chart—because if there were, it would mean you and your partner are identical, which would be boring and probably terrible.
Synastry is not a verdict. It doesn't determine whether your relationship will succeed or fail. It's a map, not a fortune. It shows you the terrain—the mountains, the valleys, the rivers you'll have to cross. It doesn't tell you whether you'll make the journey. That's up to you.
Synastry is not a weapon. Don't use it to prove you're "right" or to justify why you're "stuck." Don't say, "Well, our Mercuries are square, so I guess we'll never communicate." That's not insight. That's avoidance masquerading as astrology.
What synastry actually is: a diagnostic tool. It shows you where you're in sync, where you're misaligned, and where you've got opportunities to grow. It gives you a vocabulary for the patterns you've already been living. And if you use it right, it can help you argue better, love smarter, and stop taking things personally that aren't personal.
The planets that matter in synastry
Here's what I actually look at with clients. Not every planet—just the ones that matter most for understanding a relationship.
☀️ The Sun: Your Core Selves
The Sun represents your essential identity—who you are at your core. In synastry, this shows how your basic selves relate to each other.
What to look at:
Sun conjunct, trine, or sextile: You get each other. There's an ease, an alignment, a sense that you're playing on the same team. This is classic "compatibility."
Sun square or opposite: Your fundamental styles are different. One is fire, the other earth. One is impulsive, the other deliberate. That's not a problem—it's just a challenge to understand.
Sun-Sun hard aspects: You're going to have to work to understand each other's core drives. But the work is worth it—it's where growth happens.
The therapist translation: Sun aspects show you whether you feel seen in the relationship. If you don't feel seen, you'll feel invisible or resentful. If you do, you'll feel supported and understood.
What it means for you: When you're both feeling seen by each other, the relationship has a solid foundation. When one of you feels unseen, the whole structure starts to wobble.
🌙 The Moon: Your Emotional Needs
The Moon is your emotional interior—your needs, your defenses, your subconscious patterns. This is the most important part of synastry, because the Moon is where you get triggered.
What to look at:
Moon conjunct, trine, or sextile: You intuitively get each other's emotional needs. You're on the same wavelength. You can read each other's moods without words.
Moon square or opposite: Your emotional wiring is different. One needs silence, the other needs words. One processes alone, the other processes out loud. This is where the fights happen—because you're speaking different emotional languages.
Moon conjunct the other person's Sun: They see you—deeply and intuitively. This is a powerful bonding aspect.
The therapist translation: Moon aspects show you whether your emotional needs are aligned. If they are, you'll feel safe. If they're not, you'll feel anxious or invalidated—and you'll fight about things that aren't really about the thing.
What it means for you: The Moon is the part of you that gets scared. When you understand your partner's Moon, you understand what scares them—and you can choose not to push that button.
💬 Mercury: Your Communication Styles
Mercury is how you think, speak, and process information. In synastry, this determines whether you can actually talk to each other.
What to look at:
Mercury conjunct, trine, or sextile: You speak the same language. You finish each other's sentences. You're on the same mental wavelength.
Mercury square or opposite: You process differently. One is fast, the other slow. One is abstract, the other concrete. This doesn't mean you can't communicate—it just means you'll need translation.
Mercury in the same element: You understand each other's mental rhythms. Fire + Fire = fast and passionate; Earth + Earth = slow and practical; Air + Air = intellectual and curious; Water + Water = intuitive and emotional.
The therapist translation: Mercury aspects show you the communication dynamic. If you're in a hard aspect, you'll often feel misunderstood—and you'll need to develop specific strategies for bridging the gap.
What it means for you: If you feel like you're "always fighting," look at your Mercuries. It might not be a values conflict. It might just be a speed and style conflict.
❤️ Venus: How You Love and Express Affection
Venus is your love language, your values, and what brings you pleasure. This is the planet of connection, attraction, and relational style.
What to look at:
Venus conjunct, trine, or sextile: You show love in ways the other person naturally receives. This is the "easy" connection—the sense that you just get each other's affection.
Venus square or opposite: You show love differently. One is words, the other is actions. One is emotional, the other practical. Again—a translation need, not a failure.
Venus in the same element: You share similar values about connection and pleasure.
The therapist translation: Venus aspects show you how you receive love. If you're in a hard aspect, you'll often feel unappreciated—not because the other person doesn't care, but because they're showing care in a language you don't speak.
What it means for you: When you feel unloved, check your Venus aspects. It's probably not that they don't love you. It's that they're loving you differently than you need.
🔥 Mars: How You Fight and Desire
Mars is your drive, your passion, and your conflict style. In synastry, this shows how you navigate tension—and attraction.
What to look at:
Mars conjunct, trine, or sextile: You have complementary energy. Your drives align. You're on the same page about what you want and how to get it.
Mars square or opposite: Your conflict styles are different. One is direct; the other is indirect. One needs to resolve quickly; the other needs to process slowly. This is where the real fights happen—not about the thing, but about how you fight.
Mars-Venus aspects: This is the chemistry. Mars and Venus are the two planets of attraction, and when they interact, there's often strong chemistry—even in hard aspects.
The therapist translation: Mars aspects show you how you negotiate difference. If you're in a hard aspect, you'll have to work harder at conflict resolution. If you're in an easy aspect, you'll fight constructively—or not at all.
What it means for you: If you're constantly fighting about how you fight, look at your Mars aspects. It might not be the content. It might be the approach.
The houses: where the energy lands
In synastry, the houses are just as important as the planets. When someone's planet lands in your house, it activates a specific area of your life.
1st house: Your identity. They help you see yourself—or they challenge how you see yourself.
4th house: Your home and roots. They feel like family.
7th house: Your partnerships. This is marriage/partnership energy.
10th house: Your career and public life. They affect your reputation or ambitions.
The therapist translation: The house shows you where your partner's energy is going to show up in your life. If their planet hits your 4th house, they'll make you feel "at home." If it hits your 10th, they'll push you to achieve something.
What I actually look at with clients
Here's my simplified approach for couples who want to understand their synastry without getting overwhelmed:
Step 1: Compare your Sun signs. This tells you about the macro dynamic—the big picture.
Step 2: Compare your Moon signs. This is the most important part. If you understand each other's Moon signs, you can navigate 90% of your emotional conflicts.
Step 3: Compare your Mercuries. This tells you how to talk to each other. If you're in a hard aspect, you'll need to build specific communication habits.
Step 4: Compare your Venuses. This tells you how you show and receive love. If you're in a hard aspect, you'll need to learn each other's love languages.
Step 5: Compare your Mars placements. This tells you how you fight and desire. If you're in a hard aspect, you'll need to develop specific conflict resolution strategies.
Step 6 (optional): Look for planets in the 4th, 7th, and 10th houses. These are often where the relationship feels most impactful.
The hard truth about "bad" aspects
Here's what I've learned after hundreds of synastry charts:
Some of the strongest, most enduring relationships have "challenging" synastry.
They aren't easy. They aren't effortless. But they're growth-oriented. The friction, the misalignment, the hard aspects—they force the couple to grow up. To communicate. To learn each other's languages. To stop expecting the other person to be a mirror, and start accepting them as a complement.
Ethan and I have several hard aspects. We have Moon square Moon. We have Venus opposite Venus. We have Mercury square Mercury. If you put our chart into some compatibility calculator, it would probably tell us to stay away from each other.
And yet—we're still here. Still showing up. Still fighting, still repairing, still learning.
Because the chart isn't the final word. The chart is the starting point.
The chart tells you what you're working with. You decide what you're going to build.
How to use synastry without weaponizing it
Here are my ground rules for using synastry in your relationship:
1. Use it for curiosity, not certainty. Don't look at a hard aspect and think, "This is why we'll never work." Look at it and say, "This is where we'll need extra care."
2. Don't use it to diagnose your partner. If you see their Moon is in Capricorn, don't say, "You're emotionally unavailable." Say, "I notice you process differently than I do. Let's figure out how to meet each other halfway."
3. Don't use it to avoid your own work. It's easier to say, "We have Mars square Mars" than to say, "I need to learn to handle conflict better." Don't let astrology be an excuse for avoiding your own growth.
4. Share it together—not as a verdict, but as an exploration. Pull each other's charts. Read them together. Ask each other: "Does this match your experience? What resonates? What doesn't?"
5. Use it as a vocabulary, not a weapon. When you understand synastry, you can say things like: "I think our Moons are pulling us in different directions right now. Can we talk about what we actually need, not just what we think we should want?" That's communication. That's repair.
What I wish I'd known when I was 22
I used to think synastry would tell me whether I was with the "right" person. I used to run compatibility charts the way you run a credit check—like it was going to tell me whether I was safe, whether I could finally relax.
But that's not what it's for.
Synastry tells you what you're in for. It doesn't tell you whether you should stay.
If you're in a challenging synastry, it doesn't mean you should leave. It means you'll have to work. It means you'll have to show up, again and again, and choose to understand even when it's hard.
If you're in an easy synastry, it doesn't mean you should stay. It means you'll have to not coast. It means you'll have to keep showing up, even when it's easy, because easy can become complacent.
The chart is the beginning of the conversation, not the end of it.
The couple's synastry exercise
If you want to actually use synastry—not just read about it—try this:
Pull both your charts (free websites will do it).
Write down one thing you learned about your partner from each of these five points: Sun, Moon, Mercury, Venus, Mars.
Write down one thing they might need to know about you from each of those points.
Share your lists with each other. No defending, no explaining. Just sharing.
Ask: "What's one thing we could do differently to accommodate the other person's style?"
That's it. That's the work.
The final truth
Synastry is not a compatibility test. It's a relationship map. It shows you where the roads are paved and where they're bumpy. It shows you where you'll have to slow down and where you can speed up.
But it doesn't tell you whether to take the journey.
That's up to you.
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