How Composite Charts are Calculated

[mikestar13]

I don't have access to the sources, but this is my understanding of the way it's done. Examples:

2-chart composite:

A Mo 15 Ge + B Mo 25 Vir = 75 + 175 = 250; 250 / 2 = 125 = Composite Mo 5 Le

This is how we would calculate in the tropical zodiac if these were tropical longitudes, the numbers would be identical if the sidereal zodiac if we calculate from 0 Ar.
I notice the positions tend to cluster around 0 Li and avoid 0 Ar (they would cluster around 0 Sc if we calculated from 0 Ta). Of course, geometrically, it would be equally valid to say Composite Mo 5 Aq, this doesn't affect hard or soft aspects meaningfully (may interchange conjuction/opposition or sextile/trine), but will flip sign and house position 180 degrees. How do we discern which is correct? I would guess the shorter arc, which won't always match the above type of calculation. Example: A Su 20 Pi + B Su 10 Ar = 350 + 10 = 360; 360 / 2 = 180 = 0 Li! Never mind the composite of two points in exact opposition.

3-chart composite:

A Me 0 Ar + B Me 10 Ta + C Me 20 Ge = 0 + 40 + 80 = 120; 120/3 = 40 = Composite Me 10 Ta

But are not 10 Vir and 10 Cp equally valid geometrically? This changes the aspect structure meaningfully as well.

TMSA could do these calculations quite easily (looking ahead to version 0.6), but rigorous definition is imperative.

Emotionally, I don't want to do this. I have no faith in composites and I reject the underlying theory of the relationship as an entity in itself, but I will if there is sufficient demand. I am interested in discussion of the math of composites.

[Jim Eshelman]

In a two-person composite (the usual scenario), the problem evaporates for most purposes because the two possible midpoints oppose each other. From the point of contacts with angles or aspects with other planets, this makes no functional difference - they would like identical on a 90° dial. It would make a difference if one values sign or house values. Even then, house values for opposing houses have more similarities than differences.

One might argue that the "near midpoint" (smaller gap) gets priority. I can't find a logical path that actually supports that.

Multi-party composites: The rule has always been to add'em up and divide. This produces increasingly irregular results the more people are added. The geometry changes with the number of parties. If one were to vary the traditional formula, it seems to me the best theory is the one I just rejected above, finding the smallest gap. This at least increases the chances you will be on an axis of symmetry.

This is all theory. I remain skeptical.

[Jupiter Sets at Dawn]

I don't use composites and have no interest in them. I also reject a relationship as an entity that has a chart, and if it did, a composite chart wouldn't be the chart.

I keep hearing about the wonderful relevant charts composite users see all the time, but in practice, there's a lot of wide aspects and still not many hits. I put it under the "even a stopped clock is right twice a day" rule of anecdotal evidence.

I'd rather not see it cluttering up TMSA. Just because some people want to "research" composite charts doesn't mean it should be included. And frankly I don't see a composite chart as all that hard to set up if somebody really wants to.

[Jim Eshelman]

While agreeing more than disagreeing with JSAD (including on her TMSA opinion), please tolerate some counterpoibt:

The idea that a relationship is a "thing unto itself" with its own identity and lifespan has always felt true - it's an idea with a very gripping sense of truth which, of course doesn't mean it's factually true. The same symptoms can arise from the messier, more complicated interweaving of the individual charts much as overtones "don't exist" in their own but by consequence of other things that separate voices are doing in the same time and place.

There are a couple of things that produce mathematical for.ms in a composite that make it look like an expressive chart. These exist separate from the composite so they neither confirm nor deny that the composite has its own effect. I mentally rule these out when assessing whether a composite seems impressive.

One is: If both people have the same aspect, the composite will have that aspect (with their orbs averaged). How we would interpret the aspect in the composite resembles how we would interpret both people having it. (Anna-Kria's Venus squared my Neptune +4°58'. My Venus squared her Neptune -5°44', both wide. Averaging these orbs, our composite had a Venus-Neptune square with a -0°23' orb.)

Or, another example: I have Mercury conjunct Saturn +2°24'. Anna-Kria had Mercury conjunct Saturn -5°06'. The composite has the conjunction -1°21', their average. But Marion has not the conjunction but a Mercury-Saturn square, orb -1°22'. Her square and my conjunction average to a semi-square: The composite has a Mercury-Saturn semi-square, orb +0°31'.

The other is: If the same two-planet co-aspect exists both directions between the charts, it will exist in the composite (with orbs averaged). For example, Marion and I each have Mercury opposite the other's Venus, so we have a Mercury-Venus opposition in the composite. (My Mercury is 2°07' shy of opposite her Venus. Her Mercury is 4°22' shy of opposite my Venus. The composite has a Mercury-Saturn opposition with a 2°14' orb, the average of those two.)

Other similar factors emerge mathematically when they are shared by the two charts, e.g., Marion and I both have a 1H Sun, sop the composite has a 1H Sun. (This could easily flip to 7H with a small quirk in the exact placement of everything,) She has Mars in 5H, my Mars is conjunct the 5th cusp, so we have Mars in 5H in the composite. Is any accurate meaning in this from the composite place or from us sharing the natal placement? That's what is always so hard to tell and, ultimately, has made composite charts hardest to assess.

[mikestar13]

I'm much more inclined to JSAD's viewpoint. With regard to Jim's counterpoints, they suggest that the composite is a potentially useful tool for visualizing such situations, but that doesn't establish the composite chart as valid in and of itself. I question the validity of transits to the composite chart and regard the progression and directions of a composite chart as outright ludicrous. If latter idea has any validity at all, surely it must be the composite of the progressions, not a progression of the composite.

What is clear is that relationships can make less expressive factors in one's nativity more powerfully expressive, particularly long term intimate relationships (whether or not romantico-sexual). Relationships cannot give expression to factors that do not exist in the nativity, and sometimes composites give that impression.

I entirely reject the idea of a relationship as an entity in itself. I love Terry and in last extremity would give my life to save her and count the price cheap. But she is she and I am I, while we can be beneficent influences in each other's lives (and this can make the relationship seem to have a life of it's own), I can neither live her life nor die her death, nor can she mine.

[Jim Eshelman]

I question the validity of transits to the composite chart

I get it - and yet the composite has always seemed pretty responsive to transits. I have no theoretical problem with transits to midpoints - they seem to work, they're just not usually worth noting - and it isn't against reason that the specific midpoints composing a composite chart would have more importance than others.

For example, our wedding was planned without every looking at our composite, yet it has:

t Sun co. c Jupiter 0°39'
t Venus sq. c Uranus 0°08'
t Asc sq. c Uranus 0°20'
t MC op. c Venus 0°40'

If latter idea has any validity at all, surely it must be the composite of the progressions, not a progression of the composite.

That's how it's calculated, yes. I've seen a couple of interested demo examples, haven't followed it myself.

What is clear is that relationships can make less expressive factors in one's nativity more powerfully expressive

Beautifully put.

Relationships cannot give expression to factors that do not exist in the nativity, and sometimes composites give that impression.

This might be an argument against composites, or it might be guidance on how to realistically use a composite.

If this were followed through, we'd have to shave the definitions carefully. Simple synastry - the interaction with the other person's chart can introduce many things that strictly "do not exist in the nativity." The very nature of most Uranus synastry contacts is that they bring utterly new, surprising things into one's life. I think this isn't a disagreement but a wordsmithing issue.

I entirely reject the idea of a relationship as an entity in itself.

You aren't alone in that. And I'm not saying you're wrong, only that every important relationship I've had has always felt like this is wrong. There always was an entity "us" that seemed bigger than what was immediately happening with the two people - an "us" with which people socially interacted and thought about that was at times almost unrelated to how they thought about or interacted with either of us individually - an "us" that had its own life and reason for which we were simply convenient firewood. - As mentioned, something akin to overtone theory allows this to be explained in the absence of a composite chart.

I'm also thinking of a composite as a "chart of the relationship itself" the way one might postulate using a chart for a first meeting or first copulation (or, for that matter, a wedding chart) as an independent chart of an independent entity. But those other charts don't actually stand up to the demands, don't really show the nature of the relationship.

[Danica]

My experience has been that one can get a thorough, solid, in-depth synastry information without ever looking at the composite. (And whenever I did look, it didn't add any info of such value to get me to start regularly doing it.)