HOUSE SYSTEMS
Regiomontanus
Regiomontanus divides the celestial equator into equal sectors, then uses house circles through the north and south horizon points to intersect the ecliptic.
The idea in context
Equal divisions of the celestial equator are projected onto the ecliptic through house circles associated with the horizon.
MAKE IT CONCRETE
An example to picture
Equal divisions on the equator generally produce unequal zodiac house widths after projection to the ecliptic.
How to read it
Use the calculated intersections as cusps; do not measure twelve equal slices on the printed zodiac wheel.
A common misunderstanding
Its equal divisions are on the equator, not on the zodiac. The geometry differs from both Porphyry and Campanus.
BRING IT BACK TO YOUR LIFE
A question to sit with
What does comparing two projection methods reveal about a placement that sits near a cusp?
Go deeper: the full reference
How to read it
This spatial construction differs from time-based systems. The projected zodiacal houses are generally unequal and retain the Ascendant and Midheaven as principal cusps.
Input and calculation limits
Compare the recorded system when comparing charts. A different house assignment reflects a different construction, not a change in the underlying planetary longitude.
Compare one choice at a time
Changing the house system changes cusps and may change house assignments. It does not move the planets through the zodiac. These are interpretive frameworks, not measured personality traits or predictions. Private chart settings do not change dating compatibility.
Try reading your own birth chart
Create a free birth chart, select the placement or symbol you are learning about, and read it alongside this lesson. A planet’s sign, house and aspects add context; keep your recorded birth time and chart settings in view.
Connect the ideas
Placidus
A time-based quadrant system that divides the diurnal and nocturnal motion used to define intermediate house cusps. The Ascendant and Midheaven anchor the 1st and 10th cusps.
2 min readWhole Sign
The entire zodiac sign containing the Ascendant is the 1st House. Each following sign forms the next house, with cusps at sign boundaries.
2 min readEqual House
The exact Ascendant degree begins the 1st House, followed by eleven equal 30° sectors along the zodiac.
2 min readKoch
A time-based quadrant system using the birthplace latitude and the diurnal arc associated with the Midheaven to construct intermediate cusps.
2 min read