HOUSE SYSTEMS
Everyone agrees on where the planets are. Astrologers do not always agree on how to slice the sky into twelve houses. The planet positions stay the same; the house a planet lands in can shift depending on the method. Here are the three you are most likely to meet.
WHOLE SIGN
The oldest method, and the one Hellenistic astrologers used for roughly a thousand years. The entire sign rising on the Ascendant becomes the First House; the next sign is the Second, and so on. Every house is exactly thirty degrees. It is simple to compute, and quirks like intercepted signs cannot occur.
PLACIDUS
A time-based method. The cusps are marked in two-hour steps from your birth: the degree rising at birth is the First House cusp, then where that degree has moved about two hours later is the next, and so on. Because signs spend unequal time on the horizon, the houses come out unequal, more so the farther from the equator you were born.
PORPHYRY
Prioritizes the four angles. The Ascendant and Midheaven are computed exactly and become the First and Tenth cusps; the arc between each pair of angles is then split into three equal parts for the houses in between. A middle path between equal and time-based systems.
Why we use whole-sign
For an app that reads the sky the way the ancients did, whole-sign is the honest choice: it is the system the Hellenistic astrologers actually used, the one Egypt, Greece, Canaan, Carthage, and Rome would all recognize.
It also fails gracefully. The time-based systems need your birth minute to be exact; a half-hour error can push a planet into the wrong house. Whole-sign only needs the rising sign, so an approximate birth time still gives a sound chart. Real ancient method, and steadier when the records are imperfect.
SEE YOUR HOUSES →