House cusp
HellenisticRenaissance & early modernModern WesternTraditional doctrineEditorial synthesis
Definition
The boundary where one house begins. Where a cusp falls depends entirely on the house system in use, which is why two charts for the same birth can place a planet in different houses.
Also called: Cusp · House boundary
In more depth
A chart divides the circle into twelve houses, and a cusp is the longitude at which each one starts. In Whole Sign houses the cusps coincide with sign boundaries: the sign containing the Ascendant becomes the first house, and each following sign becomes the next house in order. Quadrant systems instead derive cusps from the horizon and meridian, so their houses are unequal.[1]
The practical consequence is that a body near a cusp can change house between systems, and early modern practitioners were already working with tabulated quadrant cusps rather than sign boundaries. This is a difference of method, not of accuracy, which is why the platform labels which system produced the cusps you are looking at.[2]
References
Numbered citations in the text link to the records below; each record links to the full source registry.
- Chris Brennan. Hellenistic Astrology: The Study of Fate and Fortune. Amor Fati Publications. 2017. Modern practitioner interpretation View source record
- William Lilly. Christian Astrology, Modestly Treated of in Three Books. T. Brudenell for J. Partridge & H. Blunden, London. 1647. Historical primary source View source record