Decade

Definition

In older astrological terminology, a decade is a ten-degree division of the zodiac, more commonly called a decan or decanate. Because each zodiac sign spans 30 degrees, every sign contains three decades: 0–10 degrees, 10–20 degrees, and 20–30 degrees. The term should not be confused with the ordinary meaning of a ten-year period.

Astrological Meaning

Traditional astrologers used these divisions to add detail to a planet’s placement within a sign. Depending on the system, each decade may be assigned a planetary ruler, image, or symbolic quality. One well-known approach is the Chaldean system of decan rulers, based on the traditional planetary order. Other traditions use triplicity rulers or distinctive symbolic figures. Consequently, interpretations can differ, so the governing method should always be identified rather than assumed.

Why It Matters

A decade can refine natal, horary, electional, or mundane chart interpretation without replacing the meaning of the sign, house, planet, or aspect involved. For example, two planets in the same sign may occupy different ten-degree sections and therefore receive different secondary symbolism. This distinction can supply nuance, especially in traditional techniques involving planetary dignity and rulership. It is best treated as one interpretive layer among several, with the broader chart providing the main context.

Related Encyclopedia Entries

• Traditional Astrology
• Astrological Terminology
• Natal Chart
• Decan
• Planetary Rulership
• Essential Dignity