Natal astrology is the science of personality, motivation and purpose. And as such, it offers thousands of ways to look at an individual birth chart to determine who a person is and (pardon the cliché) what makes him or her “tick.”

But the three most basic aspects of personality in your natal chart—think of your chart as a snapshot of the sky taken at the moment you were born—are what astrologers often call the Big Three: your sun, moon and rising signs.

Almost everyone knows what their sun sign is, but that’s usually the only thing most people learn about their personal astrology. The sun sign determines the largest part of your ego self: personality, motivation, strengths to develop and weaknesses to overcome, and some aspects of your physical body and appearance. But to say that the sun sign is the sum total of who you are and leave it at that is to miss the point of natal astrology.

The rising sign (a.k.a., the ascendant), while not as central to determining personality and motivation as the sun sign, is the aspect of the chart which most influences your outward appearance and how others see you. The rising sign, like the moon sign, is largely determined by your mother and the things she did to influence the actual time of day you were born (for example, being active or not, inducing labor or having a C-section).

But the moon sign has its own strong connection with the mother, and often the sign your moon is in can tell you what kind of parent she was.

My moon sign is Virgo, and although my mother is a Leo, as a parent she was critical, a bit detached and had a very strong interest in health and nutrition (no junk food!)

But more than that, your moon sign determines your own emotional personality, what you took from the mothering (or lack thereof) you received and how you incorporated that into your own emotional makeup.

When I do chart readings, I always try to impress people with the importance of the moon as one of the Big Three, the determinants of personality and self, and probably the most important aspect in your chart when it comes to emotions.

The moon is the luminary (not really a planet) in your chart that is most influenced by outside forces—and the most changeable (think of the tides). Got your feelings hurt by someone? It probably had something to do with the moon.

What got me really thinking about the moon and its effect on people was the recent series of eclipses in July and August. Emotions seemed to be heightened everywhere. I noticed myself and others reacting to outside forces more than usual, and I got a lot of clients going through little emotional dramas that seemed much bigger than they really were.

At the same time of these eclipses, Saturn, the planet of restrictions, limitations and wet blankets was transiting directly over the moon in my birth chart. If I didn’t know anything about astrology, I would have been wondering why I felt so depressed. But because I did know, I worked with Saturn (well, most of the time) and gave it what it needed (disciplined action, close attention to time and routine). In turn, I felt a lot better.

My point in all of this? First, know your moon sign. Many of you probably already do. Second, learn a little more about astrology if you are interested. Or at least learn more about your astrology. I have classes every few months, or I can do private classes. Buy an astrological calendar such as Jim Maynard’s Celestial Influences or Pocket Astrologer (the smaller version). This will tell you what sign the moon is in and even when to do your gardening to get the best results!

Or at the very least, just pay attention to the phases of the moon, using almost any calendar. You’ll notice that the new moon–sun and moon in the same sign–is generally a better-feeling, more harmonious time. It’s a great time for parties or other gatherings. It is also the perfect time to set intentions. The full moon is more tense. This is due to the moon and sun being in opposite signs. Begin cleaning projects around this time. Get rid of things. Use the energies of the full moon to release anything unneeded.