The following degrees are in antiscion with each other:

0°00'01" Aries -- 29°59'59" Virgo
0°00'01" Taurus --29°59'59" Leo
0°00'01" Gemini --29°59'59" Cancer
etc.

So, to my understanding, the precise 0°00'00" points are in antiscion with each other as follows...

0°00'00" Aries -- 0°00'00" Libra
0°00'00" Taurus -- 0°00'00" Virgo
0°00'00" Gemini -- 0°00'00" Leo
etc.

However, this is only for the precise 0°00'00" points, as when you move the former forward by 1 second, the latter changes to the following signs.

I double checked this using Astro Gold. If I load the chart of the Sun at 0°00'00" Taurus, then load the antiscia chart, it puts the Sun's antiscion at 0°00'00" Virgo.

Is this accurate that the precise 0° points of these signs are (albeit briefly) in antiscion with one another?

Some explanations on Antiscia

https://www.skyscript.co.uk/antiscia.html

lunatisca wrote: Thu Jan 23, 2025 1:39 am The following degrees are in antiscion with each other:

0°00'01" Aries -- 29°59'59" Virgo
0°00'01" Taurus --29°59'59" Leo
0°00'01" Gemini --29°59'59" Cancer
etc.

So, to my understanding, the precise 0°00'00" points are in antiscion with each other as follows...

0°00'00" Aries -- 0°00'00" Libra
0°00'00" Taurus -- 0°00'00" Virgo
0°00'00" Gemini -- 0°00'00" Leo
etc.

However, this is only for the precise 0°00'00" points, as when you move the former forward by 1 second, the latter changes to the following signs.

I double checked this using Astro Gold. If I load the chart of the Sun at 0°00'00" Taurus, then load the antiscia chart, it puts the Sun's antiscion at 0°00'00" Virgo.

Is this accurate that the precise 0° points of these signs are (albeit briefly) in antiscion with one another?

In answer to your question: yes.

Think of it like this: You know how to find a midpoint, right? It's (P1 + P2) / 2 = MP, where P1 and P2 are the points and MP is the midpoint.

You find antiscia the same way, only in this case you already know the midpoint: it's either 0 Cancer (90) or 0 Capricorn (270). The unknown in this case is one of the "P" points in the equation. So, using the same formula, the antiscion of 0 Aries:

(0 + P2) / 2 = 90
0 + P2 = 180 ; * multiplied both sides by 2
P2 = 180 ; * antiscion = 0 Libra

Antiscion of 0 Taurus:

(30 + P2) / 2 = 90
30 + P2 = 180 ; * multiplied both sides by 2
P2 = 150 ; * subtracted 30 from both sides. Antiscion = 0 Virgo

Antiscion of 0 Gemini:

(60 + P2) / 2 = 90
60 + P2 = 180 ; * multiplied both sides by 2
P2 = 120 ; * subtracted 60 from both sides; Antiscion = 0 Leo

I used 90 (0 Cancer) here because it was closer. You can use 270 (0 Capricorn) if you like. N.B.: If you get a final result greater than 360, subtract 360. Hope this helps.

--stargeezer

The equation above, (P1 + P2) / 2 = MP, works just fine for finding antiscia, but it can be streamlined a bit.

To review, MP represents either 0 Cancer (90) or 0 Capricorn (270). For convenience, use whichever one is closer to the point whose antiscion you're trying to find, but either one will work.

P1 is the point whose antiscion you want to find.
P2 is the antiscion, which is unknown when you start out.

We can rearrange (P1 + P2) / 2 = MP as MP * 2 - P1 = P2.

Let's say we want the antiscion of 0 Scorpio. That's 210 from 0 Aries. So

270 * 2 - 210 = P2
540 - 210 = 330 ; * the antiscion of 0 Scorpio is 0 Pisces. (See note at end.)

If we want the antiscion of 0 Virgo, that's 150 from Aries, so

90 * 2 - 150 = P2
180 - 150 = 30 ; * the antiscion of 0 Virgo is 0 Taurus

See? Works fine and eliminates the "multiply both sides by 2" step in the last post.
Just remember, if you get a final result greater than 360, subtract 360. If you get a final result below zero, add 360.

Edit 01/26/2025: In the first example above, I originally identified 330 degrees as 0 Aquarius. This is incorrect; 330 is 0 Pisces. I've corrected it.

--stargeezer

What is the difference between
moon antiscion ASC and moon square ASC?

Fidibus wrote: What is the difference between
moon antiscion ASC and moon square ASC?

Moon square Asc means the Moon is 90° (or 270°) from the Asc, measured along the ecliptic.
Moon antiscion Asc means the Moon is the same arc distance from the solstice axis as the Asc, but as if mirrored on the other side of that axis. E.g. Asc at 10° Gemini and Moon at 20° Cancer (arcs of 20° from solstice). Or Moon at 25° Aquarius, Asc at 5° Scorpio (arcs of 55°).
If the Asc is at 15° Taurus and the Moon at 15° Leo, or v.v., or at respectively 15 Aquarius and 15° Scorpio, the Moon would be both square the Asc and also its antiscion (two 45° arcs=90). Traditional doctrine (e.g Abu Mashar) then considers the square to behave not really like a square, more positive/sympathetic.

Antiscions are very interesting. They're easier to spot and get a feel for if you use a chart with the solstice axis vertical, such as the "0° Aries" house system available in Solar Fire, then you can see the mirror arrangement easily (before checking if it really is in close enough orb, on which opinions differ).
Morin wrote (in the book on Aspects, in Astrologia Gallica) that an antiscion has to be also at the same declination, not just the same longitude, and that if a planet or the Moon goes beyond the maximum declination of the Sun (+ or - about 23°26'), then it has "no antiscion". This is not the usual traditional/classical doctrine (see Deborah Houlding's article mentioned by James), but is interesting as if seems to prefigure the notion of "out-of-bounds" planets, behaving like wild cards (for example, Trump and Elon Musk both have OOB Mercury).
Graham

Graham F wrote: Sat Feb 08, 2025 5:17 pm

Fidibus wrote: What is the difference between
moon antiscion ASC and moon square ASC?

Moon square Asc means the Moon is 90° (or 270°) from the Asc, measured along the ecliptic.
Moon antiscion Asc means the Moon is the same arc distance from the solstice axis as the Asc, but as if mirrored on the other side of that axis. E.g. Asc at 10° Gemini and Moon at 20° Cancer (arcs of 20° from solstice). Or Moon at 25° Aquarius, Asc at 5° Scorpio (arcs of 55°).
If the Asc is at 15° Taurus and the Moon at 15° Leo, or v.v., or at respectively 15 Aquarius and 15° Scorpio, the Moon would be both square the Asc and also its antiscion (two 45° arcs=90). Traditional doctrine (e.g Abu Mashar) then considers the square to behave not really like a square, more positive/sympathetic.

Antiscions are very interesting. They're easier to spot and get a feel for if you use a chart with the solstice axis vertical, such as the "0° Aries" house system available in Solar Fire, then you can see the mirror arrangement easily (before checking if it really is in close enough orb, on which opinions differ).
Morin wrote (in the book on Aspects, in Astrologia Gallica) that an antiscion has to be also at the same declination, not just the same longitude, and that if a planet or the Moon goes beyond the maximum declination of the Sun (+ or - about 23°26'), then it has "no antiscion". This is not the usual traditional/classical doctrine (see Deborah Houlding's article mentioned by James), but is interesting as if seems to prefigure the notion of "out-of-bounds" planets, behaving like wild cards (for example, Trump and Elon Musk both have OOB Mercury).
Graham

You didn't unterstand my question, Graham.
I know the mathematical answer.
That is not what I meant.

What is the difference in interpretation, Graham?

Fidibus wrote: You didn't unterstand my question, Graham.
I know the mathematical answer.
That is not what I meant.

Sorry, silly me ! So I guess you mean how to interpret Asc square Moon vs Asc antiscion Moon.
You could note that a square in longitude is usually considered a "hard", "tense" or somewhat negative aspect, while antiscions are considered to indicate a sympathy and semi-equivalence between two points. I've often seen it described as being "as if" a planet was also present at its antiscion point, so maybe Moon antiscion Asc is more like a conjunction - even if it also happens to be a square, as in the example I gave. Classical authors suggest that a square which is also an antiscion is thereby modified in its effects (e.g. Abu Mashar, Great Introduction, trans. Dykes, Bk VI.5).

For your original question, re Exact Antiscion Points, I can recommend the Morin passage I mentioned, to see what you think of his take on the exact point: Astrologia Gallica Bk 16 Ch 15, trans. Holden. For Morin, any body with ecliptic latitude will have two antiscions, one where its parallel of declination crosses the immediate ecliptic nearby (on the same side of the solstice axis), and another one where that parallel crosses on the other side of that axis (sort of a "scion" and its antiscion...)

I'm only just experimenting with this, but I think you can get a visual representation of Morin's approach in Solar Fire, by opening a chart, then going to Harmonic/Transform > Longitude equivalent declination . That will generate a chart showing where Morin's "nearby antiscia" are. Then repeat ditto, but choosing "Longitude equivalent declination (Ant)" to get the second one, the antiscion proper, beyond the solstice axis. Then a biwheel to see how e.g. Moon and Asc are placed re their respective antiscia (Asc will not of course be altered by declination in the SF derived charts, as it has no latitude, so longitude unchanged). When bodies are near the solstice points, the jumps in placement can be quite big. This works OK if there is no Out-of-bounds planet (I check first). But whereas Morin says a planet beyond the Sun's maximum declination is sort of "off the map" (like modern OOB) and has no antiscion, SF will put it back inside the "bounds" (i.e. the tropics) by the same distance it is beyond (explained in the help pages), which seems wrong to me.

I find this stuff interesting because it gives a new perspective on how to conceptualise the tropîcal zodiac, as more of an "earth zodiac", defined first by angles on the horizon between the solstice points, where the Sun, Moon etc rise and set through the year, as seems to have been the practice in ancient Egypt and is still apparent in the Hellenistic use of "steps" (bathmoi) e.g.Valens Bk I Ch 18.
Graham

Graham F wrote: Sun Feb 09, 2025 3:54 pm For your original question, re Exact Antiscion Points, I can recommend the Morin passage I mentioned, to see what you think of his take on the exact point: Astrologia Gallica Bk 16 Ch 15, trans. Holden.

Just for the record, Placidus (a contemporary of Morin and inspired by the same naturalist trend) also used antiscia based on the actual bodily position of a planet (that is, including its latitude), usually known as zodiacal parallels or parallels of declination.

Thank you Graham.