Antiscia and Contra-Antiscia: Reading Two Reflections of a Chart

A point at 5° Capricorn has its antiscion at 25° Sagittarius and its contra-antiscion at 25° Gemini. One source position produces two different results because the reflection axes differ.

In the tropical zodiac, antiscia reflect across the 0° Cancer–0° Capricorn solstitial axis. Contra-antiscia reflect across the 0° Aries–0° Libra equinoctial axis. A point’s contra-antiscion is opposite its antiscion.

Hermes lists the two operations separately in its Zodiac transformation menu:

Here, λ is the point’s longitude on the full 0–360° circle. An antiscion is a derived point, rather than a new physical position of the planet in the sky.

Where do the two reflection axes lie?

Reflection across an axis at angle a can be written as normalize(2a − λ). For antiscia, a = 90°, giving 180° − λ. For contra-antiscia, a = 0°, giving −λ, or 360° − λ after normalisation.

The antiscial axis has endpoints at 90° and 270°. Consequently, 0° Cancer and 0° Capricorn are their own antiscia. Similarly, 0° Aries and 0° Libra are their own contra-antiscia.

A point on the axis staying unchanged does not mean the operation has failed. Choosing only one of these four points for your first check may make the transformation difficult to see.

The singular is antiscion and the plural antiscia. The opposite point is a contra-antiscion; contra-antiscia is the plural.

Calculate the result in degrees and minutes

First convert the position within a sign to full-circle longitude: Aries starts at 0°, Taurus at 30°, Gemini at 60°, and each subsequent sign adds 30°. Capricorn begins at 270°, so 5° Capricorn is 275°.

For its antiscion:

180° − 275° = −95° → 265° = 25° Sagittarius

For its contra-antiscion:

360° − 275° = 85° = 25° Gemini

normalize puts the answer in the interval 0° inclusive to 360° exclusive. Add 360° to a negative result; write 360° as 0°. This final step matters particularly at sign boundaries.

For an example with minutes, take 20°35′ Leo = 140°35′. Its antiscion is 39°25′, or 9°25′ Taurus; its contra-antiscion is 9°25′ Scorpio. The shortcut of subtracting a position within its sign from 30° must include minutes: 30°00′ − 20°35′ = 9°25′.

At an exact sign boundary, normalise an answer of “30° of the preceding sign” to 0° of the next. The antiscion of 0° Leo is therefore 0° Gemini, rather than an answer left labelled 30° Taurus. A sign-pair table alone is insufficient for these boundary cases.

Which calculation appears in Lilly?

On pages 90–92 of Christian Astrology, William Lilly gives antiscial sign pairs and degree–minute calculations, then identifies the contra-antiscion as the point opposite the antiscion. The 20°35′ Leo example above appears in that section. The digital text we used has a title page identifying the 1659 second edition, despite “1647” in the filename. The relevant section occupies PDF pages 114–116.

This provides a historical example of calculation and interpretation. Lilly’s astrological judgments do not establish a verified effect or guarantee an outcome for a present-day event. Here we use the calculation method; a contact’s interpretation should involve more than an automatic “good” or “bad” label.

Reflecting one point differs from reflecting the whole chart

Finding a planet’s antiscion and comparing it with another planet in the source chart compares two layers. Reflecting every point produces a reflected chart as a whole.

For a simple exercise, let source point A be 40° and source point B 140°:

• A’s antiscion is 140°, coinciding exactly with source B.
• B’s antiscion is 40°.
• The short longitudinal angle between A and B is 100° in the source chart and remains 100° in the fully reflected chart.

“A’s antiscion conjoins source B” therefore describes a different comparison from “A and B conjoin within the reflected chart.” The second statement is false in this example.

A common reflection preserves the magnitude of the short longitudinal angle, while reversing its direction. From 40° to 140°, you advance 100° in zodiacal order. From their reflections, 140° to 40°, you advance 260° in that order; the shorter distance is still 100°. This calculation alone establishes neither applying/separating status nor physical speeds or every other kind of aspect.

Remember the circular boundary when measuring a contact. A reflected point at 359°50′ and a source target at 0°10′ are 0°20′ apart by the short arc. This is an example of distance calculation, rather than a recommended orb. Record your chosen interpretive orb separately.

Does Hermes also reflect the house cusps?

In Hermes, antiscia and contra-antiscia use the shared longitude transformation. It processes planets, available zodiac points, house cusps, the Ascendant, Midheaven and available Vertex points. These two options reflect each original cusp individually; they do not build a new equal-house ring as the Tobey path does.

Reflection reverses cusp order too. If source cusps 1 and 2 are at 20° and 50°, their antiscia are 160° and 130°, respectively. The arc between them remains 30°, with its direction reversed.

Do not sort the reflected cusp values into ascending numerical order and assign house numbers again. Doing so changes the numbering of the house ring. When planets and cusps share the same reflection, examine their relationship along the reversed arc.

The transformed Ascendant and Midheaven are also derived positions within this chart. Do not read them as newly calculated physical horizon or meridian positions for the same time and place.

Why are declination equivalents and sidereal origins separate questions?

The antiscia formula uses longitude. To establish whether two actual planets have equal or opposite declinations, compare their declinations directly. A reflected-longitude match alone does not prove that relationship.

The Hermes coordinate option “Longitude Equivalent, Antiscia” takes a different path. This option first derives a longitude equivalent from declination and then reflects that value. The Antiscia chart transformation reflects the source longitude directly. Their shared label does not give them identical inputs. Declination equivalents are covered in a separate guide in this series.

The solstitial and equinoctial names in this guide refer to the tropical zodiac. Changing the longitude origin and reflecting around the same numerical axis can produce a different answer from reflecting first and then changing the origin.

For arithmetic only, take a tropical longitude of 40° and a hypothetical ayanamsha of 24°:

The difference is 48°, twice the chosen 24° offset. These operations do not express one geometrical axis in two coordinate systems: they apply the same numerical formula to different origins. To retain the same physical axis after changing the origin, its coordinate must change too.

This is not a measured result for the order of operations in Hermes’s sidereal path. Begin your product comparison with the tropical zodiac and Normal coordinate view. Record sidereal and other transformation combinations as separate trials.

Build a comparison in Hermes

Use the proposed synthetic sample 20 March 2000, 12:00:00 UTC, 41° north, 29° east; Gregorian calendar. Convert the time appropriately if the form expects local time. Actual Hermes outputs for these data have not been generated here; the degrees above are teaching examples.

1. Create the source chart. Choose the tropical zodiac, Placidus, Normal cusp setting, Normal coordinate view and Normal transformation. Keep other settings, including the node type, unchanged.
2. Record longitudes. One planet, the Ascendant, Midheaven and at least two consecutive cusps make a useful initial sample. Note the displayed rounding if full precision is unavailable.
3. Select the Antiscia chart. Compare each result with normalize(180° − λ) calculated from its source value.
4. Return to the same source and select Contra-antiscia. Calculate normalize(360° − λ). Do not use the antiscial output as a new source.
5. Compare both outputs. Each point’s antiscion and contra-antiscion should be 180° apart. Check reversed cusp order and house numbering separately.
6. Choose a source-chart target. Measure the short longitudinal distance from a reflected planet to that target. Identify this as a comparison across layers.

Keep the source date/time/place, zodiac, house system, full transformation code, source and result longitudes, house numbers and program version in your notes. If you compare fresh calculations with transformations from an existing chart pane, record that path too.

For saving settings and distinguishing them from new-chart defaults, see the Hermes Chart Settings guide. Name the comparison precisely in your interpretation: “A’s antiscion lies this far from source B.” That wording identifies the source planet, reflected point and measured contact.