Midpoints
The midpoint of two planets A and B is the longitude (A + B) / 2 — the degree exactly halfway between them on the shorter arc. The midpoint is read as a meeting place: when a third planet sits on or near the midpoint of A and B, the tradition treats it as activating their composite signification. The interpretation is structural: 'Sun = Mars / Saturn' is read as the Sun foregrounding the combined Mars–Saturn theme.
The geometry
Every pair of planets has two midpoints — the near midpoint on the shorter arc, and the far midpoint on the longer arc, 180° away. The two are mirror images across the pair's axis. Both are valid; the near midpoint is the more commonly cited.
Reading midpoints
A midpoint is sensitive when another planet sits on it within a tight orb. Tradition uses 1° to 2°; tighter is more reliable. The midpoint then has a four-letter formula: A = B / C reads as 'planet A activates the combined principle of B and C.' Sun = Saturn / Pluto, for instance, is read as the Sun foregrounding that pair's combined signification — a structural foregrounding, not a forecast.
Cosmobiology and the modern formulation
Modern midpoint analysis as a full discipline was crystallized by 20th-century writers whose work remains in copyright; Netra does not reproduce or paraphrase those formulations. The technique itself is older — the geometry is in Manilius, and Renaissance astrologers used midpoints under the older name 'mid-axis points.' Netra surfaces the geometry and its classical antecedents only.
How Netra uses it
The Midpoints tab computes the midpoint trees for every body pair and lists every third-planet contact within configurable orb. The four-letter formula notation (A = B / C) is rendered on each row. Both near and far midpoints are computed; the view defaults to near.
Illustrative natal chart — the technique above applies to any chart you compute in Netra.
Sources
- Manilius, Astronomica
- Jean-Baptiste Morin, Astrologia Gallica
- Public-domain Renaissance compendia of mid-axis interpretation
See Sources for the full corpus and the public-domain policy.
Related
- Essential dignities — The five-fold table of planetary strength by zodiacal placement — domicile, exaltation, triplicity, term, and face.
- Antiscia and contra-antiscia — Solstice-axis reflections — a hidden contact line that runs through every chart.
- Arabic parts (lots) — Derived points formed from the geometry between three chart positions — the Lot of Fortune is the canonical example.