The moon. She's the one I look for when I'm trying to figure out how to connect with someone. She rules the sign of the Great Mother -- Cancer -- and she represents women, motherhood, domesticity, home, family, how we nurture and soothe, our reaction to fear, our emotional selves, and our inner landscape.
Her domain is a big one and she rightfully takes her place as one of the "Big Three" in astrology (sun, moon, rising).
The moon doesn't work on the rational principles of, say, your sun sign. She is all feeling and intuition. As far-reaching as her influence is, however, she is also the astrological body most affected by other planets, signs, and aspects. Sit her next to Saturn, for example, and she struggles to express her feelings. (Heck, she'll even deny them and pretend she doesn't have any feelings.) Sit her across from Mars and her protectiveness may turn violent. Square her with Uranus and she will not be told what to do and can't be held down. Place her in harmony with Venus, however, and you get the kindness and sensitivity of the "sweetheart placement."
I often say to people that if I could know only one placement in a chart, I would want to know a person's moon sign. It tells me how the person might experience fear, what they need to feel secure, and their style of connection.
When I was first dating my Scorpio husband, I was aware that, as a Scorpio, he might have difficulty trusting others. But when I saw his Gemini moon, I knew that I was in for a lot of conversations about a lot of topics. Gemini loves to talk. No--I mean it. Loves talking. And Gemini also loves learning about a lot of different things. Like a curious child or trivia geek, Gemini wants to know a little about everything and then share it with the world.
What does that tell me? 1.) He's not a typical, taciturn Scorpio, 2.) he saves his chitchat for those he feels safe and happy with, and 3.) rebuffing his conversations will be hurtful. Talking and sometimes even blabbering on about things is his way of truly, genuinely connecting in a human way. (We're not talking about professional connections, we're talking about establishing friendship and trust.)
In my naivete, I thought that as an air moon myself (Libra), I could keep up with his chatter, but boy, was I wrong! There are times when he can jabber away at the end of the day, and I just don't have the energy for it after a day of work. However, I remind myself that it's his Gemini moon trying to connect with me, and that's a beautiful thing coming from a self-protective, trust-shy Scorpio. My Aries sun conjuncts my Aries Mars, it would be altogether too tempting for me to tell him to shut up, but my astrological knowledge about my husband keeps me kind and compassionate with his love language. If I were to rebuff him because I was impatient or irritated, I would not only hurt his Gemini moon, but his Scorpio suspiciousness would tell him, "See? This is what happens when we trust other people. Let's not do that again and protect ourselves," and I would damage the relationship.
I'm not saying that we need to martyr our time to every chatterbox, but I knew from my husband's moon sign that it meant something deeper to him. And as his partner, I had to value his conversations in the spirit they were given. Furthermore, talking his feelings out is very important to him. When he yammers on about the awful state of the world, it's his way of processing his emotions. All air moons do this--they have to talk and think through their feelings. Discussion is important to all air moons, and especially so for Gemini--the chattiest of them all! (Air signs are Gemini, Libra, and Aquarius.)
The moon sign is so important when you're trying to coexist harmoniously with someone. This includes friends and coworkers. An Aries moon might have a temper and could be impatient, but they're likely very protective of their people. A Libra moon like me hates confrontation. You know how I said Gemini loves to talk? Well, Libra moon hates confrontation. Libra also loves gossip, so when a Libra moon asks you if you've heard about the latest scandal around Harry and Meghan, they're trying to bond with you. That one is easy to understand, but how about this one -- when a Virgo moon nitpicks, that's their way of letting down the wall and trying to connect. (I had to remember this when a Virgo moon corrected my "there's nothing!" with "no, there's just not a lot." I told myself: Don't go all Aries on her and flip out, she's just trying to connect with you in her Virgo way.)
In synastry readings where I look at the energies between two people, I look to the moon to see if they can cohabit well. My husband's moon trines mine, so I knew that we had a good shot at domestic harmony, and it turned out to be absolutely true. The ease with which we cohabit together is exactly the type of effortlessness described by a trine. If someone's moon squares, opposes, or quincunxes their partner's moon, however, it's not to say they can't cohabit -- it would just take work, mature communication, and compromise.
OG astrologer Steven Forrest often says that the sun is what you need to take care of to be sane, but the moon is what you need to take care of to be happy. Completely agree. The moon can't be argued with, bargained with, or negotiated with. Your feelings are exactly what they are, and they are a huge part of what makes you, you. It's also what makes your friends who they are, and knowing a person's moon sign is incredibly useful in interpersonal relationships!