✦ Astrology Glossary
Koch House System
A house system that divides the birth chart based on the ecliptic's intersection with the local horizon and prime vertical.
The Koch House System is a method for dividing the birth chart into 12 houses, developed by German astrologer Walter Koch in the 1960s. It is based on the ecliptic's intersections with the local horizon and the prime vertical, making it a "house system of the ecliptic" that emphasizes the local sky's geometry.
How it works
Unlike the Placidus system (which uses time-based arcs), Koch calculates houses by dividing the semi-arcs of the ecliptic points that rise and set at the birth location. The Ascendant and Midheaven (MC) are fixed, and the intermediate house cusps are determined by the ecliptic positions that reach the horizon at specific intervals after or before birth. This system is often used in Western astrology, especially for natal chart interpretation, and is popular in German-speaking countries.
In practice
The Koch system tends to produce unequal house sizes, similar to Placidus, but with slightly different cusp positions, particularly in mid-latitudes. It works best for charts born between the Arctic and Antarctic circles; near the poles, it can become undefined. When reading a chart, astrologers using Koch may find that house placements feel more "event-oriented" compared to the psychological emphasis of Placidus. If you use Astraly's chart tool, you can switch between house systems to see which resonates with your interpretation style.
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Angles
The four most important points in a natal chart: Ascendant, Descendant, MC, and IC.
Chart Wheel
A circular diagram representing the positions of planets, signs, and houses at a specific time and place.
Cusp
The boundary line between two astrological houses, where one house ends and another begins.
Eighth House
The Eighth House in astrology governs transformation, shared resources, intimacy, and the mysteries of life and death.
Eleventh House
The house of friendships, groups, hopes, and long-term goals in the natal chart.
Equal House System
A method for dividing the birth chart into twelve houses of equal 30° arcs, starting from the Ascendant.