Uranian Synastry Chart — Cross-Midpoint Pictures on the Shared 90° Dial

What Uranian synastry does differently

Classical synastry asks which of partner A's planets aspect which of partner B's planets on the 360° zodiac. Uranian (Hamburg) synastry asks a different question: which midpoint pairs — potentially one body from each person — land on the dial position of something in either chart. The 90° dial is used because it makes quadrant-partition aspects (45°, 72°, 90°) full-weight contacts, and the eight trans-Neptunian working points are on the dial alongside the ten planets and both sets of angles.

Because the dial folds every 90° to the same visual position, a single dial-degree cluster can carry multiple classical aspects at once — Uranian practice treats this superposition as the point, not as noise. The reading convention: a cross-chart midpoint landing on your personal Sun, Moon, Asc or MC is 'the fusion of these two figures expressed through your channel'.

How the shared dial is built

Each partner's chart is cast independently: the ten classical planets placed from sub-arcsecond astronomy (VSOP87/ELP via astronomy-engine), Ascendant and Midheaven from the local horizon at each birth location, and the eight Hamburg working points from our Uranian Kepler layer. Every longitude is folded to the first quadrant (mod 90°) so both charts share the same dial space.

For cross-midpoints we scan every pair (X from partner A, Y from partner B) as well as every pair entirely within A or within B, and check whether the shortest-arc dial-midpoint (X + Y)/2 mod 90° lands within your chosen orb of any C on either dial. Pictures are labelled 'cross' when the pair straddles the two people (that's what makes Uranian synastry its own technique) and 'within' when both bodies come from one chart.

The full list is sorted tightest-first so cross-relationships with the strongest arithmetic rise to the top.

What you get

Once both birth data sets are entered:

• Both charts' classical ten, angles, and eight working points placed by sign, degree and folded dial position.
• A single 90° polar dial showing both partners' positions in distinct colours, with the four Uranian guide rings.
• Every cross-midpoint picture A(x)/B(y) : C within your orb, labelled with the source of each term and its dial deviation.
• A short gloss of the working-point vocabulary so you can parse Cupido(partner A)/Saturn(partner B) : your MC without a textbook.

Reading the shared dial

Uranian practice treats a cross-chart midpoint as the actual relationship 'figure' — the theme that exists only because these two charts are together. Sun(A)/Venus(B) : Asc(B) reads classically as 'the identity-and-affection complex expressed through B's personal presence'; Kronos(A)/Poseidon(B) : MC(A) reads as 'authority and depth expressed through A's public role'. Working points stretch the vocabulary past what the classical ten can describe.

Discipline: don't count every picture — a pairing with 80 hits at 1.5° orb is not 'intensely linked', it's noise. Uranian teachers generally ask for one or two tight (≤0.5°) cross-chart pictures sitting on the personal bodies (Sun, Moon, Asc, MC) as the load-bearing contacts. Everything else is texture.

A worked example, with real numbers

Two births at 17:30 UTC on 1 January 2000, one in London and one in Berlin. Partner A has Sun at 10.60° Capricorn (dial 10.60°) and Asc at 28.81° Cancer (dial 28.81°). Partner B, cast on Berlin's horizon, has Sun at the same 10.60° Capricorn (dial 10.60°) and Asc at 9.17° Leo (dial 39.17°). Because the birth instant is identical, the classical planets and the eight working points fold to the same dial positions in both charts — only the angles differ.

At 1° orb the tightest cross-chart picture is Uranus(A)×Pluto(B) landing on Mars at dial 58.14° with a 0.001° deviation. Note the caveat this example is built to expose: because both charts share one birth instant, every cross-chart midpoint collapses onto the single-chart midpoint set, so the pairing is mathematically real but relationally degenerate — a genuine reading needs two different birth times. Each hit is listed with its exact dial deviation so you can see how tight (or how trivially duplicated) each claim is.

What this tool does not claim

The eight Hamburg trans-Neptunian working points are hypothetical; no such bodies have been observed and the IAU does not recognise them. Their positions solve published Gaussian elements exactly; nothing about their astrological significance is empirically supported. Classical synastry remains the better-attested framework for cross-chart comparison, and we ship that separately.

Because the 90° dial folds every quadrant onto one, several aspects at once can share a dial-degree — sometimes in ways that were not intended in the tradition. This tool surfaces the arithmetic; interpretation is yours. Small residual drift between our Kepler propagation and the intended Gaussian mean-longitude progression exists at the 1900 and 2075 boundaries but is well inside any orb you'll set. Calculations run entirely in your browser. Your birth data is never uploaded, never stored on a server, and never shared.

Uranian synastry vs classical vs composite

Classical synastry cross-aspects the two 360° charts. Composite synastry builds a single chart from the midpoints of the two charts' bodies and reads it as its own entity (that's the `/tools/composite-davison` tool). Uranian synastry sits between: it doesn't reduce the pair to one chart, but it treats midpoint figures — pairs of bodies projected onto a dial — as the primary relationship symbol rather than classical aspects.

Practitioners generally don't choose between these three; they read the same pairing through all three frameworks and note where the pictures converge. This tool is honest about being one of three valid geometries.

Our method in one line

Both charts cast with Porphyry quadrant houses (whole-sign available on every chart) and eight working points from Kepler-propagated Gaussian elements; all longitudes folded mod 90°; cross- and within-chart midpoint pictures computed at shortest-arc (A+B)/2 with a user-set orb (default 1°). Reviewed by Dr. Amara Osei, Astronomy Reviewer.