House Division Calculations in Astrology Explained

In episode 313 astrologer Luís Ribeiro joins the show to explain the astronomy and mathematics underlying the calculation of the different forms of house division in western astrology.

We begin with a historical timeline showing when some of the different forms of house division were introduced, who the earliest sources are that mention them, and the time periods in which they reached the peak of their popularity.

Then we go into a detailed breakdown of the astronomy and mathematics underlying how some of the most popular forms of house division are calculated.

We focus in particular on the rationale for whole sign houses, equal houses, Porphyry houses, Alcabitius, Campanus, Regiomantanus, and Placidus.

Our goal was not necessarily to advocate for any one system or talk about which was better to use in practice, but instead to help astrologers understand how the cusps are divided according to each approach.

Towards the end of the episode we have a section talking about an astronomical instrument called an astrolabe, and showing how medieval astrologers used it in order to calculate the Ascendant, Midheaven, and other intermediate house cusps.

For more info about Luis and his work visit:

AcademyOfAstrology.eu

This episode is available in both audio and video versions below, although we would encourage you to watch the video version because there are a lot of visuals.

Timestamps

Here are some timestamps for topics covered at different points in the episode:

00:00:00 Intro

00:01:00 Luis’ book On the Heavenly Spheres

00:01:50 Luis’ research on the astronomical rationale for house division

00:04:18 Understanding the basis of house division systems

00:05:04 Why astrology students should learn astronomy

00:07:20 Famous astrologers who were astronomers

00:08:40 Requirement to draw charts by hand in some schools

00:11:45 Different types of house systems

00:14:30 House division methods through time

00:17:38 Whole sign house system and its disappearance

00:20:55 Equal house system

00:29:50 Porphyry house system

00:33:57 Alcabitius house system

00:41:03 Works on house division systems

00:43:40 Whole sign not considered a house division by some academics

00:51:25 1959 German book that acknowledges whole sign houses

00:54:03 Campanus house system

00:57:00 Regiomontanus house system

01:05:50 Astro.com house system options

01:07:30 Solar Fire house system options

01:09:34 Placidus house system

01:14:26 Primary or diurnal movement

01:17:47 The ecliptic

01:22:27 Numbering of the houses

01:27:03 Dividing the circle

01:31:43 View of ecliptic from astronomy program

01:39:59 The meridian

01:44:50 Square chart example

01:46:40 3D diagram of the divisions

01:50:00 Zenith

01:53:00 Equator

01:54:05 Equator view from astronomy software

01:56:40 View from the north in the astronomy software

01:59:10 The zodiacal belt

02:00:43 2D diagram of the divisions

02:02:09 Whole sign method

02:04:48 Equal Houses method

02:08:12 Porphyry method

02:14:44 Alcabitius method

02:19:20 Campanus method

02:24:19 Regiomontanus method

02:28:32 Placidus method

02:38:39 Length of life technique and house division

02:54:30 Better documentation needed of house systems

02:55:45 Bias in academic research

02:57:42 Errors in descriptions of house systems

03:03:33 Different cusps

03:04:36 Astrolabe basics

03:14:10 Calculating houses with an astrolabe

03:26:18 Horary astrology and the astrolabe

03:29:00 Astrology boards

03:32:07 Astrology in academia

03:34:11 The challenge of different house systems

03:38:50 Different house systems for horary and natal

03:45:31 Revised version of Luis’ book

03:46:00 Luis’ website and Astro Project

03:46:43 Upcoming episode on Helena’s work and new book

03:47:55 Closing remarks

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Transcript

A full transcript of this episode is available: Episode 313 transcript

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