Decan ruler

Definition

The decan-ruler is the planet assigned to a ten-degree segment of a sign. Each sign divides into three decans, and each decan carries a sub-rulership that colors the first ten, middle ten, or last ten degrees with the imprint of a second planet on top of the sign's own ruler. The most common modern table walks through the planets in Chaldean order across the decans of the zodiac.

In context

If your Sun sits at twenty-five degrees of Leo, the ruler of Leo is the Sun, but the decan-ruler of that third segment is Mars in the Chaldean system. The chart reads as a Leo Sun with a Mars-flavored finish: an extra heat in the way the solar expression closes a cycle. The decan-ruler does not replace the sign's ruler. It tints the segment with an additional planetary signature.

To go deeper

The decan-ruler lives inside the broader system of decanal subdivision:

• Decan: the ten-degree segment itself.
• Triplicity: three-planet share of an element.
• Term: minor dignity over uneven degree ranges.