Sun-Moon Synastry Is the Green Flag for Astrological Compatibility You Didn't Know You Needed

Sorry, but if you've ever swiped left on a dating app because a potential partner's Sun sign wasn't compatible with yours, you might have made a huge mistake. Astro enthusiasts know that Sun signs aren't the be-all, end-all of compatibility: Your and your potential partner's Moon signs, Venus signs, and Mars signs are also très important. But many people miss a major—and super underrated—green flag for compatibility. I'm talking about a little something called Sun-Moon synastry.

In astrological terms, "synastry" is a term that refers to how two peoples' birth charts interact with each other. Sun-Moon synastry means looking at how your Sun sign interacts with your partner's Moon sign, and vice versa. Because most compatibility guides focus on Sun sign only (or, more rarely, Moon sign only), they usually miss this type of compatibility.

To be specific, one of the greenest green flags for compatibility—I'm talking the brightest, most neon green you can imagine—is when your Sun sign is the same as your partner's Moon sign, or when your Moon sign is the same as your partner's Sun sign. For example, maybe you have a Gemini Sun and your partner has a Gemini Moon, or you have a Pisces Moon and your partner has a Pisces Sun.

When this happens, your and your partner's personalities will likely be different. One might be more outgoing where the other is more introverted. However, you understand each other on a deep level. It's the kind of connection where as soon as you meet someone, you feel like you've known them your whole life. You just get each other like no one else does. Next time you feel this kind of connection, pull up your birth charts and compare them. And then send a thank-you note to the stars.

Do you and your partner have this astrological green flag? Read below to see what your zodiac Sun-Moon synastry means for your 'ship.

Nothing gets you going like a little (heated) rivalry. You might have an enemies-to-lovers story worthy of a three-season TV series, or you might just get a little flirty when you beat your S.O. to the triple-word-score in a game of Scrabble. While the Aries Sun partner is likely to be more openly competitive, Aries Moon wants to win just as badly—they just tend to hide it a little better.

Your ideal date night is spending hours cuddling together on the couch while watching a romance movie. You both want to be cozy and comfy at all times, and you can both be a little lovey-dovey, too. Go ahead and indulge in your romantic tendencies. Your S.O. will appreciate your sonnets, even if the couplets don't quite rhyme. Taurus Moon might be a little more in touch with their emotions, but with their help, it won't take much for Taurus Sun to get there, too.

"Sapiosexual" is a controversial label, so I won't stick it on you. Instead, let me just say that you get turned on by your mind-blowing intellectual connection. Witty banter is like dirty talk to you, and skilled dirty talk can take your sex life to the next level. While Gemini Moon might appear more serious to others, when the pair of you are together, you get playful and silly. You can make each other laugh til your stomachs hurt.

As a pair, you might be the most emotional couple of the zodiac. You can spend hours processing your feelings and digging deep into your childhood memories. While Cancer Sun might seem more nurturing and caring on the surface, Cancer Moon is just as sensitive—if not more so. While other signs might get a little intimidated by the depth of your emotional intelligence (and eagerness to quote from The Body Keeps the Score), you're each other's perfect match.

You share a bond based on your shared creativity and generosity. While the Leo Sun partner is likely more outgoing, the Leo Moon partner can also thrive in the spotlight in the right situation—maybe they love to belt out their favorite songs at karaoke or they make TikTok fancams for their favorite shows in their downtime. You both need compliments, so don't hold back when you think your S.O. looks good. Need date night inspo? You both love to dress up and go out, making everyone jealous of how good you look together.

As a couple, you two are a little… intense. Your weekly wellness routines, synched Google calendars, and superfoods-stocked fridge can intimidate others. Which is exactly why it feels so amazing to find each other. Your daily routines help you both feel grounded, and you're both health-conscious. Virgo Sun likely appears more Type A to others, but Virgo Moon gets just as much satisfaction (if not more) from balancing their weekly budget.

Life feels like a party when you're together. A chic party with craft cocktails and a curated guest list. You both love the finer things in life, like fashion, flirtation, and fun. People might think you're superficial, but you both get a sense of deep satisfaction from looking at a beautiful painting or taking a gorgeous photo together. Out of all the couples on this list, you're the most likely to color-coordinate your outfits.

I'm going to be honest: Together and apart, you kind of scare people. You both tend to be drawn to extremes, and you're naturally deep-thinkers. Neither of you is great at small talk (though Scorpio Moon is likely a little better), but it's not because you're pretentious; you just honestly think a lot more about death than you do about the weather. Together, you can feel free to be your weirdest, goth-est, most obsessive selves.

Your connection is powered by spontaneity, honesty, and plenty of adrenaline. You don't hold back your opinions and might tend to argue a lot; however, you always have plenty of hot make-up sex afterwards. This, plus your passion for jet-setting and making spontaneous big decisions, might make other people think you're messy (though Sagittarius Moon hides it better), but it works for you two. As a couple, you're most likely to surprise your friends and family by going to Las Vegas and eloping on a whim.

The term "power couple" was invented for you. You're ambitious, hard-working, and a little bit ruthless. (Capricorn Sun leads with this, while Capricorn Moon is more likely to keep their ambition under wraps—intentionally.) Your idea of a fun date night is plotting out your ten-year plans together. It doesn't work for everyone, but it works for you. Your direct communication style and dark sense of humor might rub other people the wrong way, but together, you feel right at home.

Aquarius is often called as the zodiac's loner or rebel. Aquarius Sun is likely to have gotten used to doing a lot of things solo, while Aquarius Moon might feel isolated even when they're surrounded by friends. Both of your brilliant, eccentric minds tend to run off on tangents that are hard for others to follow, but with each other, you've finally found someone who just gets you.

Your relationship is built on your shared creativity, kindhearted nature, and wisdom. You're both "old souls," no matter how old you actually are. People tend to describe you as open-minded, artistic, and caring. Others tend to trust you and ask you for advice, even if they don't quite understand you. (Pisces Sun gets the "what should I do?" questions from almost everyone they meet, while Pisces Moon gets them from their nearest and dearest.) Together, you can live in your own little world.