What Is a Natal Chart and How Is It Calculated?

The four parts of a chart

The planets tell you what the chart is talking about. The Sun is your core and direction, the Moon your emotional needs and what makes you feel safe, Mercury how you think and speak, Venus how you love and what you value, Mars what you want and how you fight for it, Jupiter where you expand, Saturn your limits and responsibilities.

The signs tell you how those planets work. Mars in Aries is direct and fast; Mars in Libra first looks for balance. The same planet expresses itself in a different style in a different sign.

The houses tell you where they work. The twelve houses are twelve areas of life: the self, earnings, communication, home and family, creativity and children, daily work and health, partnership and marriage, shared resources, belief and far horizons, career, community and goals, withdrawal. The house a planet sits in shows the area of life where that planet comes forward.

The aspects tell you how the parts behave toward one another. A conjunction joins two planets; a trine or sextile gives flow and support; a square or opposition creates tension. Tension is not bad; the place where a person works hardest and grows most is often right there.

Why birth time matters so much

The planets' signs barely change over a day; even the Moon stays in one sign for two and a half days. But the rising sign changes roughly every two hours, and the whole house system is built from the rising sign. So in a chart without a birth time the planets' signs are correct, but which area of life each planet sits in cannot be known.

Even if you do not know your exact time, the chart can still be drawn; it is just incomplete. The way to narrow down the time is rectification: working back from the dates of important events in your life to the likely birth time.

Sun sign versus birth chart

Newspaper horoscopes look only at the Sun sign and tell everyone born under that sign the same thing. Yet two people with the same Sun sign can have completely different rising signs, Moons, Venus placements and house layouts. That is why a birth chart is personal: even two people born on the same day have different charts if their times differ.

The rising sign is often the side people see first; others meet you through your rising sign. The Moon is the side your closest people see. The Sun sits between the two, at the core of who you are.

Your natal chart in FalAstry

The chart is calculated from real ephemeris data, meaning the planetary positions come from astronomical computation, not approximate tables. Houses, aspects, essential dignities, whether the chart is a day or night chart, and the almuten, the overall ruler of the chart, are calculated too.

The natal chart is the foundation for every other tool: solar return, transits, profections, zodiacal releasing, synastry and the full natal report are all built on it. Your birthplace can be anywhere in the world; the city's coordinates and time zone are found automatically.