What every word on a birth chart means

A birth chart

A map of the sky at the moment and place you were born, drawn as a circle with the eastern horizon on the left. Everything else on this page is a detail of that one picture: where each planet was, which part of the sky it sat in, and the angles between them. It is calculated, not interpreted; two people with the same birth details get the same chart from any astrologer alive.

Sun, Moon and rising

The three placements most astrologers start with. The Sun is what you are building toward, the Moon is what you need to feel at home, and the rising sign is how you come across and the lens the rest is seen through. Two of the three need only a birth date; the rising sign needs the time.

Degrees

The zodiac is a circle of 360 degrees split into twelve signs of 30 each, and a planet’s position is written as how far into its sign it is. 14°32′ Taurus means fourteen degrees and thirty-two minutes past the start of Taurus. The number matters because aspects are measured from it: two planets at the same degree of different signs are in a precise relationship, whatever their signs.

Signs

The twelve thirty-degree slices of the sky’s circle, named for the constellations that sat behind them two thousand years ago. A sign describes the style of a planet: the same Mars pushes differently in Aries than in Pisces. The signs are not the stars; see the note on the tropical zodiac.

Houses

The twelve areas of life, counted anticlockwise from the eastern horizon at your birth: the 1st is you, the 4th is home, the 7th is partnership, the 10th is your work in the world, and so on. A planet’s sign says how it acts; its house says where in your life it acts. Houses need a birth time, because the horizon moves through the whole zodiac every day.

Cusps

The line where one house ends and the next begins, given as a degree of a sign. The 1st cusp is the Ascendant and the 10th is the Midheaven. A planet within a degree or two of a cusp is usually read as belonging to the house it is about to enter.

House systems

There is more than one way to divide the sky into twelve houses, and the choice moves planets between houses near the boundaries. Placidus, the common modern default, divides by time; whole-sign, the oldest method, makes each house one whole sign; equal houses take thirty degrees each from the Ascendant.

Astrologers disagree about this

Without a birth time

The chart is cast for noon. The planets are placed within a degree or so, which is enough for signs and most aspects, but the Ascendant, the Midheaven and the houses cannot be found, because the horizon turns through the whole zodiac in a day. The Moon moves about thirteen degrees a day and may be in either of two signs; the page says so when it is.

The tropical zodiac

Signs here are measured from the point where the Sun stands at the March equinox, so Aries always begins with spring in the north. The constellations have drifted about twenty-four degrees from the signs that carry their names since the system was set, which is why astronomy and Western astrology disagree about what sign the Sun is “in”. Most Indian astrologers use the sidereal zodiac, tied to the stars, and their charts differ by that much.

The chart ruler

The planet that rules your rising sign. The tradition reads it as the planet that steers the whole chart: its sign says how you go about things, its house says where your life tends to happen, and its aspects carry more weight than the same aspects to any other planet. It is the thing a working astrologer looks at right after the Sun, Moon and rising, and the thing most apps never mention.

Astrologers disagree about this

A stellium

Three or more planets in one sign or one house. It is where the weight of a chart sits: that style, or that area of life, is louder than everything else, and any transit through it lands on several planets at once. A person with a stellium is often described by it more than by their Sun sign.

Astrologers disagree about this

The Ascendant

The degree of the zodiac rising over the eastern horizon at the minute you were born, also called the rising sign. It changes sign roughly every two hours, which is why the birth time matters so much. It is read as the face you show and the way you meet things, and it sets where all twelve houses begin.

The Midheaven

The highest point of the zodiac overhead at your birth, the cusp of the 10th house. It is read as your public work, reputation and direction. Like the Ascendant, it needs a birth time.

The Descendant

The degree of the zodiac setting in the west at the moment you were born, exactly opposite the Ascendant and the cusp of the 7th house. Because it is fixed by the horizon it needs a birth time, and it moves about a degree every four minutes. It is read as partnership: the qualities you meet in other people, and what you are drawn towards in a close one-to-one relationship.

The IC

The lowest point, opposite the Midheaven, and the cusp of the 4th house. Read as home, roots and private life. IC is short for imum coeli, the bottom of the sky.

The lunar nodes

The two points where the Moon’s path crosses the Sun’s, always exactly opposite each other. They are not bodies; nothing is there. The tradition reads the North Node as the direction of growth and the South as what comes easily and is worth leaving. Eclipses happen when a New or Full Moon lands near them.

Astrologers disagree about this

Aspects

The angle between two planets, measured round the circle. Some angles are counted as meaningful and the rest are not: 0° (conjunction), 60° (sextile), 90° (square), 120° (trine), 180° (opposition), and the awkward 150° (quincunx). An aspect is a relationship: it says the two planets are working together, against each other, or side by side.

Conjunction

Two planets at the same degree, or within a few degrees, so their natures fuse. It is the strongest aspect and the most neutral: whether it helps depends entirely on which planets are involved.

Opposition

Two planets 180° apart, facing each other across the chart. Read as a tension between two sides that both want a hearing, and often lived out through other people. The Full Moon is the Sun and Moon in opposition.

Square

Two planets 90° apart. The friction aspect: the two are pulling in directions that do not fit, which is uncomfortable and, in the tradition, where effort and growth come from. Most people’s hardest and most productive stretches show a square.

Trine

Two planets 120° apart, usually in signs of the same element. The easy aspect: the two cooperate without being asked. It is the one people are glad to have and the one whose gifts go unnoticed because they never had to be worked for.

Sextile

Two planets sixty degrees apart, which is two signs, and usually read as a mild version of the trine. The traditional reading is an opportunity rather than a gift: something that helps if you act on it and quietly does nothing if you do not. Because it is a softer aspect, most astrologers allow it a smaller orb than a conjunction or an opposition, so it has to be closer to count at all.

Quincunx

Two planets 150° apart, in signs that share neither element nor mode. An awkward fit that needs adjusting for rather than resolving. Many astrologers leave it out; this chart includes it with a tight orb.

Orb

How far an aspect is from exact. Two planets are almost never at precisely 90°, so an aspect is counted if it falls within a few degrees, and that allowance is the orb. The tighter the orb, the stronger the aspect is read. In a birth chart this app allows up to 7° for a square or trine and 8° for a conjunction or opposition, a degree more when the Sun or Moon is involved; for transits it allows only 3°, so the daily pages talk about what is actually pressing.

Astrologers disagree about this

Applying

The faster planet is still moving toward the exact angle, so the aspect is tightening. An applying aspect is read as stronger and still to come, in a birth chart as a theme that develops through life.

Separating

The exact angle has already passed and the faster planet is moving away from it, so the aspect is loosening rather than tightening. In a birth chart it is read as something largely worked through, or a theme that was loudest early and has since settled. In a transit it means the peak is behind you. The opposite is an applying aspect, which is the one still building, and most astrologers give an applying aspect the greater weight.

Elements

The twelve signs sort into four groups of three: fire (Aries, Leo, Sagittarius), earth (Taurus, Virgo, Capricorn), air (Gemini, Libra, Aquarius) and water (Cancer, Scorpio, Pisces). Fire acts, earth builds, air thinks, water feels; it is a shorthand for temperament. Counting how many of your planets fall in each is the quickest sketch of a chart.

Modes

The other sorting of the signs, into three groups of four: cardinal (Aries, Cancer, Libra, Capricorn) start things; fixed (Taurus, Leo, Scorpio, Aquarius) hold them; mutable (Gemini, Virgo, Sagittarius, Pisces) adapt them. Each season begins with a cardinal sign, runs through a fixed one and ends in a mutable one.

Transits

The planets keep moving after you are born, and a transit is one of them passing over or making an angle to a point in your birth chart. Transits are how astrology talks about timing: the chart is fixed, the sky moves across it. The slow planets, Saturn outwards, make transits that last weeks or months; the Moon crosses your whole chart every month and is barely counted.

Retrograde

A planet appears to move backwards against the stars for a stretch, because the Earth is overtaking it or being overtaken on the inside track. Nothing actually reverses. In a birth chart, a retrograde planet is read as turned inward, working over its subject privately before showing it. Mercury does this three times a year, so it is the one people notice.

Direct

Ordinary forward motion through the zodiac, which is what a planet does the great majority of the time. The word only exists because the alternative does: a planet that has been retrograde and resumes its normal direction is said to station direct, and that day is often read as the point where something that had stalled starts moving again. Everything except the Sun and Moon goes retrograde at some point; those two never do.

Stations

The day a planet appears to stop before turning retrograde or turning direct again. The tradition treats the stationary days as the strongest of the whole retrograde: the planet is standing still on one degree, and anything of yours it is touching then gets its full attention.

Ingress

A planet crossing from one sign into the next. For the Moon this happens every two and a half days; for Saturn every two and a half years; for Pluto once or twice in a lifetime. The slow ones mark changes of era.

Lunations

A New or Full Moon. Each one falls in a particular sign and, in your chart, a particular house, so the same New Moon starts something different for each person. The New Moon is read as a beginning and the Full Moon as a culmination or a seeing clearly.

New Moon

The Sun and Moon at the same degree, so the Moon is invisible. The start of the monthly cycle, read as the moment to set something in motion. It happens in a different sign each month, working round the zodiac once a year.

Full Moon

The Sun and Moon opposite each other, so the Moon is fully lit. The cycle’s peak, read as things coming to light or to a head. It falls in the sign opposite the Sun’s, so a Full Moon in Pisces happens while the Sun is in Virgo.

Waxing

The fortnight from New Moon to Full, when the lit part of the Moon grows a little larger each night. It runs about fourteen days and passes through the first quarter at the halfway point. The tradition puts beginnings, building and gathering here, on the plain logic that the light is increasing, and most Moon practices that ask you to start something are pointed at this half.

Waning

The fortnight from Full Moon back to New, when the lit part shrinks each night until the Moon disappears. It runs about fourteen days, through the last quarter at the halfway point. Read as the half for finishing, releasing, clearing out and resting, which is the same plain logic as the waxing half read backwards. The dark few days at the end are traditionally for doing nothing in particular.

Void of course

The stretch after the Moon makes its last exact aspect to a planet in its current sign and before it enters the next. The Moon is still moving; it just has nothing left to do in that sign. The tradition says what is begun then comes to nothing, which is why the When page steers around it for beginnings, and why it does not mind it for meditation.

Astrologers disagree about this

Planetary hours

Daylight divided into twelve equal parts and the night into twelve more, so an hour is rarely sixty minutes and changes with the season. Each is ruled by a planet in an old fixed order, starting at sunrise with the ruler of the day: the Sun on Sunday, the Moon on Monday, and so on. This is why the hours depend on where you are standing, not where you were born.

Solar return

The moment each year when the Sun comes back to the exact degree it held at your birth. It is your birthday by the sky rather than the calendar, and can fall a day either side. Some astrologers cast a whole chart for that instant and read it as the year ahead.