Decan
A decan is a ten-degree subdivision within a zodiac sign, which spans thirty degrees. Each sign therefore breaks into three decans, and astrology traditionally assigns each a ruling planet that colors its tone. This division, inherited from ancient Egypt where each decan answered to a constellation, allows a finer reading of a planet according to its exact position within its sign.
Three shades within a sign
Think of the decan as three rooms in the same house. A Sun at the start of Leo does not tell quite the same story as a Sun at the end of Leo: the decan brings that nuance. Depending on the tradition followed, its rulership shifts, but the idea holds: to refine what a placement already says by looking at exactly where it falls.
An Egyptian inheritance
The decans come from the thirty-six stars the Egyptians watched rise to mark the hours of the night. That memory survives in your chart: behind the mechanics of degrees hides a very old gesture, that of inhabiting time by watching the sky. The decan ties your chart to that long lineage of observers.
Sources
- , 36 Faces: The History, Astrology and Magic of the Decans (2014)
- , The Houses: Temples of the Sky (1998)