Composite chart

Meaning

A composite chart turns two charts into one. Each planet is placed at the midpoint of its two positions: halfway between one person’s Sun and the other’s, halfway between the two Moons, and so on for every body and angle. The result is read as the chart of the relationship itself, a third presence with its own character, beside the two people who make it.

Where synastry asks how two people affect each other, the composite asks what they make together. A relationship can have a purpose, a mood and habits of its own that neither person has alone. Its Sun is read as what the bond is for, its Moon as how it feels from the inside, and its Ascendant as how it meets the world.

A composite has no moment and no place of its own: nobody was born at it. That is why its houses and some of its details are built by convention, and why some astrologers prefer the Davison chart, made from a real moment and place.

In practice

• The composite Sun’s house is read as the field where the relationship lives most: the 10th for a shared work or public role, the 4th for a home, the 9th for travel, study or belief.
• The composite Moon shows the emotional climate: a Moon in a water sign is read as tender and close, in an air sign as talkative and light.
• Saturn on an angle of the composite is read as a bond built to last, with duties and structure.
• Transits to the composite are followed like transits to a birth chart, to read seasons in the life of a couple, a friendship or a team.
• The Davison chart, cast for a real moment, can be read the same way, side by side with the composite: one is a real sky, the other a blend of two.

Origin and history

The idea may be older than its first book, but the technique spread with John Townley’s book The Composite Chart (1973). Robert Hand’s Planets in Composite (1975) gave readings for each composite placement and made the method a standard of modern relationship astrology. In his book Synastry (1977), Ronald Davison proposed another chart of the relationship: the sky of the moment halfway in time between the two births, at the place halfway between the two birthplaces. It is known as the Davison chart.

How Ulune calculates it

• The bodies: each composite position is the midpoint of the two natal longitudes, taken the shorter way round the circle. Mercury never strays more than about 28° from the Sun, and Venus about 47°. So when the shorter midpoint of either falls more than 90° from the composite Sun, Ulune takes the other midpoint, on the Sun’s side.
• Motion and declination: speeds and latitudes are averaged, and each declination is worked out from the composite position itself. Nothing is recast through the ephemeris.
• The angles: the composite Ascendant and Midheaven are the midpoints of the two Ascendants and of the two Midheavens.
• The houses are built from those axes in the charts’ house system, the first person’s if the two differ. In a quadrant system such as Placidus, the angles are the cusps of the 1st, 4th, 7th and 10th houses, and the cusps between them sit where the two charts put theirs, on average, within each quadrant. Equal houses start at the composite Ascendant, whole signs at its sign. When the two Ascendants are nearly opposite and the axes no longer form a quadrant, Ulune uses equal houses and says so.
• Aspects and sect: aspects use the birth chart’s orbs. With no horizon, the chart counts as a day chart when the composite Sun is in the 7th to 12th house, which sets its sect.
• When either birth time is unknown: the angles and the houses are noon stand-ins, marked so.
• The Davison chart is shown beside the composite. Ulune casts it for the moment halfway between the two births in universal time, at the mean of the two latitudes and of the two longitudes, taken the shorter way round. Because it is a real sky, its motion, declinations and dignities hold as in a birth chart.