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Relationship Astrology: Synastry in Your Birth Chart

Comparing two people's birth charts can show if a relationship will sizzle or fizzle

By Maria DeSimone

What is it about that special someone that gives him or her the ability to make your knees weak, your heart race, and your brain to turn to mush? In a word, it's called chemistry.

Astrologically, there are a few clear indicators to help you understand why one person has the power to give you an immediate rush while someone else leaves you feeling flat.

Synastry is the branch of Astrology concerned with how one person’s planets interact with your planets, thus creating a unique synergy of energy flow between the two of you. Astrologically speaking, it’s possible to know if someone is attracted to you and whether or not you share a mutual affinity. Of course, astrological indicators of attraction won’t tell us much about the potential for love and endurance ... but hey, it’s a start. And isn’t it fun to explore what your planets might do to the planets of your latest crush?

What follows is a lowdown of the dominating indicators of chemistry between birth charts. Keep in mind that the conjunction is the granddaddy of all aspects when it comes to chart comparison. With the following aspects, if two planets are in the same sign and in close degree you have a guarantee of sexual attraction! Sextiles and trines in close orb are the next best. Squares and oppositions, while providing the attraction of friction, often also comes with a challenge.

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This is the classic indicator not only for attraction, but for compatibility. When you share a Sun-Moon tie with someone there’s an instant rapport that just can’t be beat. One’s essence (Sun) is embraced and understood intuitively (Moon). The Moon person can count on the Sun person and this pair will easily "get" each other. When this combination is found along with one of the sexier indicators of chemistry, it’ll likely be a love match that’s hard to beat.

Sun-Mars (or, if someone’s Mars falls in your 5th House of Creativity)

When the Sun and Mars are linked, passion is fortified! The Sun person feels energized in this relationship and his or her sex drive is immediately aroused in the presence of the Mars person. Mars feels prompted to pursue the Sun person in an assertive way. The thrill of the chase is intoxicating with this connection!

Sun-Pluto (or, if someone’s Sun falls in your 8th House of Intimacy)

A potent, obsessive, and instant connection is felt where identities seem to merge and you each feel a strong fated pull towards the other. With this link comes the potential for deep intimacy physically and psychologically. You want each other... body and soul. There’s something oh so sexy about a person who can take you to the depths and heights of being.


Emotional arousal is a strong factor in any passionate relationship. Sure, the occasional one night stand might have its place in your life. But when it comes to sensitive chemistry, this link is hard to beat. You each get to each other’s core, affecting each other in a visceral way. Sex is not just sex when you share this link. Connecting sexually to your mate enhances your feelings and deepens your bond.

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This is by far the most famous inter-aspect for attraction. The planet of love (Venus) meets up with the planet of desire (Mars) and voila -- you’ve got chemistry! There is a magnetic force that seems to pull the two of you together when you share this link. This is the kind of connection that makes your knees go weak when your special someone kisses you.


Many a one night stand was created thanks to this link! A Venus-Uranus connection is known as the "love at first sight" aspect. Electric attraction is obvious between you and anyone you share this connection with. In fact, it is such an exciting sensation that you simply must scratch the itch ... immediately! This contact alone however, is not enough to assure longevity. Still, it is all you need for someone to take your breath away!

Venus-Pluto (or, if someone’s Venus falls in your 8th House of Intimacy)

If you’re looking for deep, intense attraction that leads to a transcendental love experience, then this is the link to share! This connection is all about the power of love, intimacy and deep sexual sharing. Sexual intimacy evolves to the highest possible level under this inter-aspect. We often find ourselves incredibly vulnerable and under the spell of someone who’s Venus aspects our Pluto or vice versa.


With this link, you have a pure, unadulterated physical attraction to one another. Mars is desire and passion and the Ascendant symbolizes the physical body as well as the identity projection. This is hot stuff because together, you’re both sexy -- and you know it!

Mars-Pluto (or, if someone’s Mars falls in your 8th House of Intimacy)

Deep erotic urges and physical desire is inspired with this link. All-encompassing passion is at the root of this connection ... so it’s certainly not for the faint of heart! In the case of Mars-Pluto however, only the favorable aspects are encouraged since the square and opposition might be a contributing factor to an obsessive, overly controlling, or even abusive relationship if the shadow rears its ugly head.

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