Morinus Houses
Definition
Morinus is one of the ways of dividing a chart into twelve houses. It splits the celestial equator — the projection of Earth's equator onto the sky — into twelve equal 30° segments measured from the meridian (or from where the equator meets the zodiac, depending on the author), then carries each segment onto the zodiac along a line of longitude. The result is twelve houses of equal right ascension, the equator's own measure of position. Their cusps do not usually line up with the local Ascendant and Midheaven, so here the angles do not fall on the 1st and 10th cusps.
In Tradition
Modern Western astrologers treat Morinus as a specialised system whose main strength is staying mathematically regular at every latitude — including the polar regions, where Placidus and other day-arc systems fail. Because the angles do not land on cusps, people who use Morinus usually read the Ascendant and Midheaven as separate sensitive points alongside the house cusps, rather than as the main house anchors. Most modern astrologers who adopt Morinus do so deliberately, for high-latitude charts or for research.
In Practice
To work out Morinus cusps, software steps in 30° increments along the celestial equator from a starting point and carries each step onto the zodiac along the line of longitude through it; the twelve zodiac positions that result become the house cusps. The astrologer reads each natal planet by its Morinus house, alongside its whole-sign or quadrant-system placement. Because the cusps do not line up with the local horizon and meridian, angular emphasis is kept by treating the Ascendant and Midheaven as separate sensitive points. In polar latitudes — above the Arctic Circle or below the Antarctic Circle — Morinus produces a clean twelve-house division where Placidus and Alcabitius cannot.
Historical Origin
The system is named after Jean-Baptiste Morin de Villefranche (1583–1656), the French mathematician-astrologer who developed it in his Astrologia Gallica (Hague, 1661). Morin put forward the right-ascension division as a corrective to what he saw as geometric inconsistencies in the Placidus and Regiomontanus systems. It saw limited uptake in the 17th and 18th centuries and was largely revived in the modern era as a research option for high latitudes; Robert Hand records it in surveys of historical house frameworks.
Further Reading
- Robert Hand, On the Heavenly Spheres
- Deborah Houlding, The Houses: Temples of the Sky