decans

Decans are divisions of the zodiac into 36 equal segments of 10 degrees each. The word decan comes from the Latin decanus, meaning “leader of ten.” In ancient astronomy, decans were star groups used by Egyptian and Mesopotamian observers to mark time at night, with the rising of each decan acting as a clock for hours. The concept was later adopted by Greek, Roman, and medieval astrologers, who incorporated decans into horoscopic practice.

Within each astrological sign, the 30-degree span is subdivided into three decans: 0–10 degrees, 10–20 degrees, and 20–30 degrees. Each decan is traditionally associated with a planetary influence, adding a layer of interpretation to the sign’s basic traits. Thus, a sign can yield three decanal profiles, often described as reflecting different temperaments, styles, or focal areas.

In modern astrology, decans are used to refine natal chart readings and timing predictions. They contribute nuance to personality assessments and to forecasts, and may inform choices in electional astrology when selecting a time to act for a specific intention.

Historical significance: the decan system also mirrored the astronomical practice of dividing the sky into rising decans, which aided navigation and ritual timing in ancient Egypt and other cultures. The legacy of decans persists in contemporary astrological traditions as a standard method to subdivide signs and assign secondary rulerships.