Antiscia and contra-antiscia
The antiscion of a degree is its mirror across the solstice axis (0° Cancer / 0° Capricorn). Every planet has an antiscion point and a contra-antiscion point (mirror across the equinox axis, 0° Aries / 0° Libra). When another body sits on or near one of these reflection points, Hellenistic and medieval astrology treats the contact as equivalent to a conjunction — a hidden aspect orthogonal to the visible one.
The geometry
A planet at 12° Aries has its antiscion at 18° Virgo (the mirror across 0° Cancer / 0° Capricorn) and its contra-antiscion at 18° Pisces (the mirror across 0° Aries / 0° Libra). The pair of axes carve the zodiac into two reflection systems: solstice-symmetric pairs (Aries↔Virgo, Taurus↔Leo, Gemini↔Cancer, Libra↔Pisces, Scorpio↔Aquarius, Sagittarius↔Capricorn) for antiscia; equinox-symmetric pairs (Aries↔Pisces, Taurus↔Aquarius, Gemini↔Capricorn, Cancer↔Sagittarius, Leo↔Scorpio, Virgo↔Libra) for contra-antiscia.
Why this is a contact
The classical reading is solar: planets equidistant from the Cancer–Capricorn solstice axis share the same daily arc and the same diurnal length. They are 'co-rising' in the older lattice. The tradition extends this physical kinship into interpretation: two planets in antiscia behave as if conjunct, even though no Ptolemaic aspect binds them. Contra-antiscia, the equinox-axis mirror, is read more as opposition than conjunction.
Orbs
Antiscia are tight contacts; classical sources allow only 1° to 2° of orb. A wider 'antiscion field' is a modern looseness, not a classical doctrine. Netra defaults to a 1° orb on the antiscia view and a 1° orb on contra-antiscia.
How Netra uses it
The Antiscia tab on every chart lists every antiscion and contra-antiscion contact between planets in the chart, with the underlying degree pair shown so the geometry is auditable. The wheel can render antiscia as an overlay if requested.
Illustrative natal chart — the technique above applies to any chart you compute in Netra.
Sources
- Firmicus Maternus, Mathesis, Book II
- Manilius, Astronomica
- William Lilly, Christian Astrology (1647), Book I
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.
- Midpoints — The half-sum point between two planets — a sensitive degree where their themes meet and a third body can activate them.
- Fixed stars and parans — The ecliptic backdrop of named stars — Aldebaran, Regulus, Spica, Algol — and their conjunctions with chart points.