Skyscript Astrology Forum

Martin Gansten wrote:But I have to disagree with this, for the simple reason that planets, just like points on the ecliptic, become circumpolar at extreme latitudes. In other words, they never rise or never set, which makes the calculation of individual semi-arcs impossible.

Hello Martin,
Yes, I understand your argument, but I'm in agreement with the position of Otto Ludwig.
The calculation of a mundane position must describe the dynamic relationship of a celestial point with the local horizon. Therefore, how the position of the object relative to the local horizon has changed over time, in terms of ascension and descension.

And circumpolar points also have a cyclical relationship with the local horizon due to the diurnal motion of the earth, even when they never touch the horizon in the entire cycle. In other words, you don't need the actual events of rising and setting for a point to have a cycle of ascending and descending in relation to the horizon going on.
The diurnal or nocturnal arc of a circumpolar point is therefore always 360 degrees. Which is the full circle described by the object in one diurnal cycle. This results in a semi-arc of 180 degrees, which is the position of Ludwig. I believe Mike Wackford was thinking along these same lines.

This gradual shift from parallel circles that cross the horizon to more and more parallel circles that do not cross the horizon when you move away from the equator, is a beautiful metaphor for the gradual shift from the tropical climate to the extremes of the poles, where everything just turns around the observer, without ascending or descending motions due to the diurnal rotation.

Astrophilus wrote:What about Porphyry houses? Much simpler than Placidus and also NOT invalidated by circumpolarity.

Only problem with Porphyry - as with all quadrant systems - is that it defines MC (culminating degree) = 10th cusp. Once the MC enters the never-rising range (1° Sag - 29° Cap in Tromso) and sinks below the horizon, houses 7-12 will be found below horizon which goes against their natural significations. The 10th house for example is supposed to be the top of the chart, so how can it be below the horizon?

Hello Astrophilus, see my reply to Martin.
About what you wrote about Porphyry: that is a beautiful summary of the strenghts and weaknesses of this system.

Hello Ruud,

Ruud66 wrote: Hello Astrophilus, see my reply to Martin.
About what you wrote about Porphyry: that is a beautiful summary of the strenghts and weaknesses of this system.

This "weakness" of defining the culminating degree as the 10th cusp applies to ALL quadrant house systems.

The only house systems not affected by it are nonagesimal house systems, for example equal houses (nonagesimal=10th cusp), WSH (nonagesimal somewhere in the 10th house) or Vehlow (nonagesimal = middle of 10th).

Best wishes,
AP

Astrophilus wrote:This "weakness" of defining the culminating degree as the 10th cusp applies to ALL quadrant house systems.

Yes, all house systems, but with the exception of Placidus houses with the Ludwig approach that I descibed above.

The only house systems not affected by it are nonagesimal house systems, for example equal houses (nonagesimal=10th cusp), WSH (nonagesimal somewhere in the 10th house) or Vehlow (nonagesimal = middle of 10th).

This leads directly into the discussion on the definition of the Midheaven and the Nonagesimal and the relationship between the two.
There seems to be as much confusion about this as there is in the field of the astrological houses.

The most concise and clear definition of the Midheaven point that I can come up with is this: the Midheaven is the culminating point of the ecliptic.
Unpacking this: the ecliptic is a model for the apparent annual cycle of the Sun, so every point on the ecliptic is a virtual position of the Sun: the Sun will occupy that place in the sky at some time during the year. So the Midheaven can also be seen as such a virtual solar position, because it is a point on the ecliptic by definition. A more poetic description of the Midheaven could therefore be the Noon-point, just like the Ascendant could be called the Sunrise-point.

Where the Midheaven is a high point in the time cycles of the Sun, the Nonagesimal is a high point in space. Taking the same ecliptic, it is now seen as a geometrical entity and it has a point in space where the altitude above the horizon is the greatest. This is the Nonagesimal and it is always 90 degrees away from the Ascendant, measured in ecliptic longitude.

In an arctic chart this has some serious consequences for what you call nonagesimal house systems. Let's take the example of the birth chart of Marie Peary, born at 77°40' northern latitude. Her chart is in Astrodatabank.
Her Midheaven is at 3°09' Capricorn, circumpolar below the horizon, but her Nonagesimal is at 26°13' Gemini, on the other side of the zodiac!

You can only make the nonagesimal house systems work here if you flip the houses and make them run clockwise, ór make the Nonagesimal the cusp 4.
These systems are definitely in trouble here also.

Astrophilus wrote:Only problem with Porphyry - as with all quadrant systems - is that it defines MC (culminating degree) = 10th cusp. Once the MC enters the never-rising range (1° Sag - 29° Cap in Tromso) and sinks below the horizon, houses 7-12 will be found below horizon which goes against their natural significations. The 10th house for example is supposed to be the top of the chart, so how can it be below the horizon?

To answer your question on the MC. Yes, the MC is the top of the chart. But also: the MC is a function of the Meridian, a circle that devides the eastern and western halves of the sky. In the east, the sky ascends (points move in the direction of the Zenith); in the west the sky descends (points move in the direction of the Nadir.)
So, nothing about whether this happens above or below the horizon.

Returning to my definition of the MC in my previous post:
If the Sun would be located in the degree of the Midheaven (it probably isn't in this chart, but just say it is...) then it would be local noon.
Pitch dark night, yes, but also local noon, because the Sun will not get any closer to the Zenith in that diurnal cycle if placed there.

Ruud66 wrote:Yes, I understand your argument, but I'm in agreement with the position of Otto Ludwig.

I'm not familiar with that name, but I understand the argument. It would be interesting to see it applied to primary directions (arguably a simpler, or at least more direct and measurable, proposition than examining the inherent symbolism of radical house placements). Do you know if anyone has tried it?

Ruud66 wrote: Yes, all house systems, but with the exception of Placidus houses with the Ludwig approach that I descibed above.

Where can I read more about the "Ludwig-Placidus house system", if you don't mind?

The most concise and clear definition of the Midheaven point that I can come up with is this: the Midheaven is the culminating point of the ecliptic.

I agree with this definition! The crucial thing about the MC is that it's the degree which has come closest to the zenith in its daily circle of 24H. It doesn't necessarily have to be above the horizon, but can also be below it (the latter is of course possible only in the Polar zone).

I don't agree with astrologers who redefine the IC or anti-culminating degree as "MC"/10th cusp just because it happens to be above the horizon in the Arctic. A circumpolar, never-setting planet would be passing twice through the "MC" in 24H - once when culminating and once when anti-culminating - but never through the "IC".

Where the Midheaven is a high point in the cycles of time, the Nonagesimal is a high point in space.

I'd say MC or culminating degree is "reaching one's individual top", upper nonagesimal "being currently highest compared to others".

When MC and upper nonagesimal coincide - which happens in the Northern Hemisphere, minus its Tropical part, at the northern solstice degree (0° Cancer) - it means "reaching the highest possible top".

The "absolute supreme top" would be the local zenith (+90° alt.), but of course a zodiac degree can only reach the zenith within the Tropical zone.

In an arctic chart this has some serious consequences for what you call nonagesimal house systems. Let's take the example of the birth chart of Marie Peary, born at 77°40' northern latitude. Her chart is in Astrodatabank. [...]
You can only make the nonagesimal house systems work here if you flip the houses and make them run clockwise, ór make the Nonagesimal the cusp 4.
Also these systems are definitely in trouble here.

Thanks for the hint - never heard about Marie Peary until now.

https://www.astro.com/astro-databank/Peary,_Marie

That's the northernmost nativity I've seen so far. Interesting! Also, what an adorable little "snow baby"...

Flipping the houses is exactly the solution I would propose. I see no problem with it: It's only logical to flip the houses, since the AC/DC axis is "retrograde" for the time that the MC/culminating degree is passing through the never-rising part of the zodiac (below the horizon).
While the horizontal axis is retrograde, planets rise/set in the reverse direction. The 12th house is the house planets go through first after having risen above the ASC, regardless in which direction this happens. 10th house is highest above horizon (containing the upper nonagesimal).

The wheel chart provided by Astro-databank is somewhat confusing, because what appears as the upper half is actually below the horizon. Peary was born shortly BEFORE sunset, not after it. I suggest the wheel chart should look more like this, using equal house cusps:



Here you can see that Peary's stellium in Virgo is still above the horizon, about to set on the DC, while her planets in Libra have already set. The 6th house is the house that planets, after having set, pass through first. 4th cusp is lowest beneath horizon (lower nonagesimal).

You can easily calculate WSH and Vehlow system for yourself:
entire sign of equal house cusp = WSH house
equal house cusp = middle of Vehlow house

But I admit that maybe the wheel format in itself is not well suited for Polar zone charts. There are things which are best seen in 3D, for example with Stellarium...

Martin Gansten wrote:I'm not familiar with that name, but I understand the argument.

Astrophilus wrote:Where can I read more about the "Ludwig-Placidus house system", if you don't mind?

The sources where I got this from are:
1) The series of articles about house systems in the arctic by Michael Wackford here on this site. https://www.skyscript.co.uk/polar1.html etcetera.

2) The Wiki article by Dieter Koch on the Astrodienst site. The interesting paragraph about the polar problems: https://www.astro.com/astrowiki/en/Plac ... m#Problems where he makes a reference to Otto Ludwig.

At the bottom of the Wiki page is a dead link to the house tables that I calculated for the Placidus houses at 60-89 degrees northern latitude.
It is still on the website here: https://www.astro.com/swisseph/Table_Ar ... acidus.pdf

I also tried my hand on an explanatory text. But I had no idea how to approach the subject back then and I decided to work around all controverial topics. Which probably makes this text unreadable. Still the section with the six examples might be useful.
https://www.astro.com/swisseph/Table_Ar ... readme.pdf

Ruud66 wrote: I also tried my hand on an explanatory text. But I had no idea how to approach the subject back then and I decided to work around all controverial topics. Which probably makes this text unreadable. Still the section with the six examples might be useful.
https://www.astro.com/swisseph/Table_Ar ... readme.pdf

Thanks, the table on p.9 is quite useful
I've been long looking for a listing of circumpolar zodiac degrees for each polar latitude. If I had known earlier, it would have saved me some work yesterday while calculating the circumpolar degrees for Ms. Peary.

Do you know a software that is good for Polar horoscopes, for example marking the circumpolar degrees automatically in the chart?

Ruud66 wrote: At the bottom of the Wiki page is a dead link to the house tables that I calculated for the Placidus houses at 60-89 degrees northern latitude.
It is still on the website here: https://www.astro.com/swisseph/Table_Ar ... acidus.pdf

Am I right in the assumption that Ludwig-Placidus system stops working on the North Pole (90°N)? Equal house system works even on the North Pole, with the approach I laid down above for Ms. Peary.

- On the North Pole, substitute "ascendant" (1st cusp) is at 0° Aries, because the Sun rises on the North Pole as soon as it passes the northward equinox degree.
- Upper nonagesimal (10th cusp) is 0° Cancer, where Sun is highest passing the northern solstice degree.
- Substitute "descendant" (7th cusp) is at 0° Libra, because the Sun sets here.
- And lower nonagesimal (4th cusp) is at 0° Capricorn, where Sun is lowest at the North Pole.

The reverse, of course, holds true for the South Pole, where 0° Libra is "ASC" and 0° Capricorn the upper nonagesimal (10th cusp).

The Poles are undeniable proof that nonagesimal systems are superior to quadrant ones, because while you can't define MC/IC here, you still have the nonagesimals.

Martin Gansten wrote:It would be interesting to see it applied to primary directions (arguably a simpler, or at least more direct and measurable, proposition than examining the inherent symbolism of radical house placements). Do you know if anyone has tried it?

This would be very interesting and much needed research. But I don't know anyone who went so far as to apply this to the PD's.
Frankly, I hardly know anyone who's interested in seriously researching the polar problem to begin with. I've seen mostly people who repeat memes to prove their own point of view about the houses. So I'm actually quite happy to find myself in this discussion with such knowledgeable people.

I have tried calculating the PD's for Mrs. Peary a couple of years ago and the results were not very satisfying to me. (But I have this feeling at all times when I research PD's.) Unfortunately I had a PC crash some time ago and I lost those files.
Do you think it is a good idea to try again?

Astrophilus wrote:Am I right in the assumption that Ludwig-Placidus system stops working on the North Pole (90°N)? Equal house system works even on the North Pole, with the approach I laid down above for Ms. Peary.

Yes, you're right. The Placidus system ceases to exist at the poles themselves, because there is no longer an ascending and descending motion in the sky. The Midheaven, the Ascendant, the Vertex and the ideas of north-east-south-west all cease to exist there.

The Poles are undeniable proof that nonagesimal systems are superior to quadrant ones, because while you can't define MC/IC here, you still have the nonagesimals.

That is a very cheeky argument
You reveal the weak point yourself when you speak of the "substitute" Ascendant.
At the poles there is no Ascendant, because nothing is rising. The "Sunrise" that happens every year is due to the annual motion, not the diurnal motion.
So, if you don't have an Ascendant, you don't have a house system, isn't it? Or maybe a "substitute" house system?