Composite chart

Meaning

A composite chart turns two birth charts into one. Each planet is put at the midpoint of its two natal positions: the composite Sun halfway between the two Suns, the composite Moon halfway between the two Moons, and so on for every planet and point [5]. The result is read as a chart of the relationship, as if the partnership were a third party with a character of its own.

A composite chart is not the sky at any moment. It is built by arithmetic, so it can show things a real sky never does. Mercury is never more than about 28° from the Sun and Venus never more than about 47°, yet in a composite either can stand far from the Sun, even opposite it [5]. For the same reason a composite planet has no motion: it is never retrograde, and its aspects are neither applying nor separating.

Which midpoint. Every pair of positions has two midpoints, one on each side of the circle, exactly opposite each other. The usual rule is to take the midpoint of the shorter arc. This keeps the composite close to both natal positions, but it can still fail near the half-circle: if the two Suns are 178° apart and the two Mercuries 182° apart, the shorter-arc rule puts the composite Mercury opposite the composite Sun. Some chart programs then move Mercury or Venus by 180° so that it lies near the Sun, as it must in a real sky [5]. Townley, on the other hand, accepts such positions: the composite shows a set of relationships, not something happening in the sky, and the planet is read on its midpoint axis either way (podcast, ep. 128) [4].

The angles and houses. Planets can simply be averaged, but the angles and house cusps raise a problem, because they depend on a place and a moment, and a composite chart has neither. There are two main answers [5]:

The midpoint method can give a chart whose Ascendant is not where the Midheaven would put it at any real latitude. The derived method keeps the angles and houses in their normal relation, but the result changes with the place chosen. Software makers and later writers associate the derived method with Robert Hand's Planets in Composite (1975); Hand's own account of it could not be consulted for this article. Townley has argued that the composite has no trigonometry of its own, so it cannot simply be relocated; to see the relationship in another place he makes a composite of the two birth charts relocated there (podcast, ep. 128) [4].

Both methods need both birth times. If either time is unknown, the composite Ascendant, Midheaven and houses cannot be trusted, and neither can the composite Moon to within several degrees.

Origin and history

The composite chart entered English-language astrology with John Townley's short book The Composite Chart [1]. Townley dates it to 1973; catalogue records of the Weiser edition give 1974. In a 2017 interview he said he had first heard of the idea about a year earlier, on the way home from an astrologers' guild meeting in New York: a fellow astrologer told him she had heard that German astrologers of the 1920s had made charts from mutual midpoints. Townley guessed that it might go back to Walter Koch, but said that nobody seemed sure [4]. No earlier composite chart is documented in the sources seen here, so the German origin remains a report. The podcast's notes trace midpoint technique in general to the Hamburg School of the 1920s [4] (see Hamburg School).

The German midpoint schools did compare charts, but by laying one chart over the other. Ebertin describes drawing the two charts on transparent paper and superimposing them sign on sign, and then the easier method of setting both on the 90° dial (p. 67) [6]; see contact cosmogram. That is a comparison of two charts, not one chart made from them.

Robert Hand's Planets in Composite (1975) is described by its publisher as the first major textbook to use the composite technique. It has chapters on casting and reading the chart and gives readings for each composite planet in each house and in each major aspect [2]. Townley has said that Hand's book was one of a series of "Planets in" titles from its publisher, and that Townley wrote the introduction for it (podcast, ep. 128) [4]. Townley returned to the subject at length in Composite Charts: The Astrology of Relationships (2000), for which Hand wrote the introduction [3].

How it is used

• Reading. The composite is read much like a birth chart: signs, houses, aspects and dignities, applied to the relationship rather than to either person. A composite Sun describes what the relationship is for; a composite Moon, how it feels to be in it; and so on.
• Aspects. Composite aspects are measured between composite positions. Because the positions are averages, a tight natal aspect in one chart can vanish in the composite, and a new one can appear.
• Transits. Transits to composite planets and angles are used to time events in the relationship. Progressions are another matter: Townley has said that he and Hand both found that secondary progressions do not work in composite charts, since the composite is a derived chart and not the chart of a moment (podcast, ep. 128) [4].
• With the birth charts. The composite is often shown in the middle of a triwheel with both birth charts round it, so that each person's planets can be read against it.

On this site. The Synastry tool has three views: Synastry, Composite and Davison. The Composite view can be shown as a triwheel, with the composite in the middle and each person's birth chart around it, or as a single wheel. Each planet and point is placed at the shorter-arc midpoint of its two positions. The angles and houses use the derived method: the composite Midheaven is the midpoint of the two Midheavens, and the Ascendant and cusps are worked out from it for the mid-latitude of the two birthplaces. If either birth time is unknown, 12:00 is used for the planets, the Moon is marked approximate, and the chart is shown without angles or houses. The Positions tab lists the composite placements; the Transits tab gives the exact dates of the major transits to the composite chart through a chosen year, and the contacts within about 1° today.

Examples

Albert Einstein (14 March 1879, 11:30 local mean time, Ulm) and Mileva Marić (19 December 1875, Titel; birth time not recorded, so 12:00 local mean time is used). Shorter-arc midpoints, tropical zodiac.

• The shorter arc. The two Mercuries are 99°52′ apart the short way round, so the composite Mercury is at 13°12′ Aquarius, 2°52′ from the composite Sun. The other midpoint, 13°12′ Leo, would stand opposite the composite Sun, which Mercury never does in the sky.
• The unknown birth time. Between midnight and midnight on her birth day Marić's Moon moved from 18°37′ Virgo to 1°26′ Libra, so the composite Moon could be anywhere from 1°34′ to 7°59′ Scorpio. Its opposition to the composite Neptune (0°40′ at noon) is therefore not certain. With no birth time for her there is no composite Ascendant, Midheaven or house to read.
• Some composite aspects (planets other than the Moon): Sun conjunct Mercury 2°52′; Venus conjunct the Node 0°44′; Uranus square Pluto 2°07′.