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. The Sun can usually be determined from the birth date alone, but if you were born on a day when the Sun changed signs, the birth time can decide which sign it was in. The same is usually true of the Moon, but it changes sign on nearly half of all days, and then the time decides it. The rising sign always 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 zodiac every day.

Cusps

The line where one house ends and the next begins, given as a degree of a sign. In OrbHeaven’s Placidus charts the 1st cusp is the Ascendant and the 10th is the Midheaven; with whole-sign houses each cusp is the start of a sign instead. 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 worked out across the whole birth date and shows only what holds for all of it. A planet that stayed in one sign shows the degrees it covered: 14° Leo means somewhere within that degree, not exactly 14°, and 14–16° Leo means it moved across them. A planet that changed sign that day shows both signs and no degree; the birth time decides which. The Moon moves about thirteen degrees a day. Aspects are marked certain when they held all day and possible when they depend on the hour. The Ascendant, the Midheaven and the houses cannot be found at all, because the horizon turns through the zodiac in a day. Timing is shown as a range when the exact day depends on the birth time.

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. Because the Earth’s axis slowly wobbles, that starting point has slid about a sign’s width against the stars since the system was set, which is why the Sun is usually in front of a different constellation from its tropical sign. The sidereal zodiac most Indian astrologers use measures its twelve equal signs from the stars instead; in its most common version the two differ by just over 24 degrees today.

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

A grand trine

Three planets spaced evenly around the chart, each a trine (120°) from the other two, so they form an equilateral triangle, usually in signs of one element. The tradition reads it as ease and natural talent in that element: a gift so fluent it can be leaned on without effort, and sometimes taken for granted.

Astrologers disagree about this

A T-square

Two planets in opposition (180°) that both square (90°) a third, called the apex. The apex is where the tension of the opposition is felt and worked out, and the tradition reads the whole figure as a chart’s engine: friction that drives effort and achievement.

Astrologers disagree about this

A grand cross

Four planets in two oppositions that cross at right angles, making four squares, so it reads as two interlocked T-squares. The tradition takes it as four-way tension that asks for balance across every side at once: demanding, and, worked with, a source of real staying power.

Astrologers disagree about this

A yod

Two planets in sextile (60°) that both make a quincunx (150°) to a third, the apex, drawing a long, narrow triangle. Sometimes called the “Finger of God”, it is read as a pointed, awkward calling that asks for adjustment and is grown into over time.

Astrologers disagree about this

A kite

A grand trine with a fourth planet opposite one of its points and sextile the other two, so the easy triangle gains a tail. The opposing planet is read as a focus and an outlet: somewhere the grand trine’s fluent gift is pushed into use rather than left idle.

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. A new sign rises about every two hours on average, but the timing is not even: depending on latitude and which sign is rising, some signs rise much faster than others. That 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 degree of the zodiac crossing your meridian, the north–south line through the sky, at the moment you were born. It is rarely directly overhead and is not always the zodiac’s highest point. In OrbHeaven’s Placidus charts it is the cusp of the 10th house; where whole-sign houses are used instead, at high latitudes, it falls within a house rather than on a cusp. 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, in OrbHeaven’s Placidus charts, the cusp of the 7th house. Because it is fixed by the horizon it needs a birth time, and it moves exactly as fast as the Ascendant opposite it. 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 degree of the zodiac exactly opposite the Midheaven, at the other crossing of the zodiac and the meridian. It is usually below the horizon, though at high latitudes it can be above it. In OrbHeaven’s Placidus charts it is the cusp of the 4th house; where whole-sign houses are used instead, it falls within a house rather than on a cusp. It is read as home, roots and private life. IC is short for imum coeli, Latin for 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 points in a chart, usually two planets, measured the shorter way round the circle. Astrologers commonly use five aspects found in Ptolemy: 0° (conjunction), 60° (sextile), 90° (square), 120° (trine) and 180° (opposition), and many also use the 150° quincunx. The angle is calculated; what it means is interpretation. An aspect counts when it falls within an allowed distance from exact, called the orb. OrbHeaven’s birth charts also count aspects to the Ascendant and Midheaven.

Conjunction

Two planets at the same degree of the zodiac, or close to it. OrbHeaven counts a conjunction within 8° in a birth chart, or 9° when the Sun or Moon is one of the pair. Many astrologers describe it as a powerful aspect and interpret the two planets as acting together; whether that is read as helpful or difficult depends on the planets involved.

Opposition

Two planets 180° apart, facing each other across the chart. OrbHeaven counts an opposition within 8° in a birth chart, or 9° when the Sun or Moon is one of the pair. It is read as a tension between two sides that both want a hearing, often lived out through other people. The Full Moon is the Sun and Moon in opposition.

Square

Two planets 90° apart. OrbHeaven counts a square within 7° in a birth chart, or 8° when the Sun or Moon is one of the pair. Astrologers class it as a hard aspect and read it as friction: the two planets pull in directions that do not fit, which is uncomfortable and, in the tradition, where effort and growth come from.

Trine

Two planets 120° apart, usually in signs of the same element. OrbHeaven counts a trine within 7° in a birth chart, or 8° when the Sun or Moon is one of the pair. Astrologers class it as a soft aspect and commonly interpret it as ease or natural cooperation between the two planets. In traditional readings, that ease is sometimes described as a talent or quality that can be taken for granted.

Sextile

Two planets 60° apart, usually two signs apart. OrbHeaven counts a sextile within 5° in a birth chart, or 6° when the Sun or Moon is one of the pair; like many astrologers, it gives the sextile a smaller orb than the other four major aspects. Astrologers generally class it as a soft aspect and often interpret it as an opportunity that becomes more noticeable when acted upon.

Quincunx

Two planets 150° apart, usually in signs that share neither element nor mode. Also called the inconjunct. It is not one of the five aspects Ptolemy used, and astrologers differ on whether to count it. OrbHeaven counts it in birth charts within 2.5°, or 3.5° when the Sun or Moon is one of the pair. Astrologers commonly interpret it as an awkward fit that calls for adjustment.

Orb

How far an aspect is from exact. Two planets are almost never at precisely the aspect’s exact angle, so an aspect is counted when it falls within an allowed distance from exact, called the orb. The distance from exact is calculated; how wide an orb to allow is an astrological convention. Tighter aspects are generally given more weight in interpretation. OrbHeaven’s birth charts allow 8° for a conjunction or opposition, 7° for a square or trine, 5° for a sextile and 2.5° for a quincunx. Transits to your chart allow 3°, 2° for a sextile and 1.5° for a quincunx. In either case, OrbHeaven allows 1° more when the Sun or Moon is one of the pair.

Astrologers disagree about this

Applying

The faster planet is still moving toward the exact angle, so the aspect is tightening rather than loosening. You tell which one you are looking at by the direction the gap is moving: closing is applying, widening is separating. In a birth chart an applying aspect is read as a theme that keeps developing rather than one already worked through; in a transit it means the exact day is still ahead of you. Most astrologers give it the greater weight of the two.

Astrologers disagree about this

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 or four 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 about every two and a quarter days; for Saturn every two and a half years; for Pluto only every eleven to thirty-two years. 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 usually 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.