Decan (astrology)

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In astrology, a decan is the subdivision of a sign. In order to give fuller interpretation to the zodiac signs, ancient astrologers subdivided each sign into periods of approximately ten days. These divisions are known as the "decans" or "decanates" and cover modifications of individual traits, attributed to minor planetary influences, which temper or blend with the ruling influence of the period. The ten-day spans are somewhat arbitrary in order to allow for the five (and sometimes six) extra days in the year beyond the 360 days required for the thirty-six decans.[1][better source needed]

In modern times, however, the assignment of decans has changed considerably.[citation needed] Each sign is allocated a triplicity, consisting of three of the four classical elements air, water, earth or fire, and is therefore subdivided into three equal parts of 10 degrees each; these parts are referred to as decans or decanates.

Each decan of a sign is assigned rulership by the planet ruling the sign and secondary rulership by the planet ruling the decan.

In Ptolemy[edit]

The decans and their rulers are assigned as follows as based on the description by the Alexandrian Egyptian astrologer, Ptolemy, from whose Tetrabiblos are derived most of the principles of western astrology:[2]

Sign Domicile ruler Exaltation ruler 0–10 degrees 10–20 degrees 20–30 degrees
Aries Mars Sun Mars Sun Venus
Taurus Venus Moon Mercury Moon Saturn
Gemini Mercury N/A Jupiter Mars Sun
Cancer Moon Jupiter Venus Mercury Moon
Leo Sun N/A Saturn Jupiter Mars
Virgo Mercury Mercury Sun Venus Mercury
Libra Venus Saturn Moon Saturn Jupiter
Scorpio Mars N/A Mars Sun Venus
Sagittarius Jupiter N/A Mercury Moon Saturn
Capricorn Saturn Mars Jupiter Mars Sun
Aquarius Saturn N/A Venus Mercury Moon
Pisces Jupiter Venus Saturn Jupiter Mars

Traditional Chaldean rulerships[edit]

"The Faces of the Planets" * (Lilly)[3]
Sign First Decan ruler

(0–9.999 deg.)

Second Decan ruler

(10–19.999 deg.)

Third Decan ruler

(20–29.999 deg.)

Aries Mars Sun Venus
Taurus Mercury Moon Saturn
Gemini Jupiter Mars Sun
Cancer Venus Mercury Moon
Leo Saturn Jupiter Mars
Virgo Sun Venus Mercury
Libra Moon Saturn Jupiter
Scorpio Mars Sun Venus
Sagittarius Mercury Moon Saturn
Capricorn Jupiter Mars Sun
Aquarius Venus Mercury Moon
Pisces Saturn Jupiter Mars

* as used as an essential dignity in astrology.

Notice that rulerships follow a repeating pattern, the Chaldaean order of the planets: Saturn, Jupiter, Mars, Sun, Venus, Mercury, Moon, based on a geocentric cosmological model.

Modern rulerships[edit]

Modern astrology updates the rulerships. Decans or "faces" are the least important of the essential dignities, representing about one-fifteenth of a planet's overall strength in medieval astrology.[4][better source needed]

The decans and their rulers are assigned as follows as based on the concepts of modern Western astrology :

Sign 1st decan ruler 2nd decan ruler 3rd decan ruler
Aries Mars Sun Jupiter
Taurus Venus Mercury Saturn
Gemini Mercury Venus Uranus
Cancer Moon Pluto Neptune
Leo Sun Jupiter Mars
Virgo Mercury Saturn Venus
Libra Venus Uranus Mercury
Scorpio Pluto Neptune Moon
Sagittarius Jupiter Mars Sun
Capricorn Saturn Venus Mercury
Aquarius Uranus Mercury Venus
Pisces Neptune Moon Pluto

See also[edit]


  1. ^ Anon (n.d.).
  2. ^ Ptolemy (1822), pp. &#91, page needed&#93, .
  3. ^ Lilly (1999a), pp. 104–105.
  4. ^ Jones (2011).


  • Anon (n.d.). "Scorpio the Scorpion". Archived from the original on 2010-01-03. Retrieved 2009-07-23.
  • Jones, Cornelia (2011). "Decans in Astrology - Planetary Rulers". Horoscopes Within. Retrieved 2021-06-30.
  • Lilly, William (1999a) [1647]. Houlding, D. (ed.). Christian Astrology, Book 1: An Introduction to Astrology; Book 2: The Resolution of All Manner of Questions. London: Ascella Publications.
  • Lilly, William (1999b) [1647]. Houlding, D. (ed.). Christian Astrology, Book 3: An Easie And Plaine Method Teaching How to Judge upon Nativities. London: Ascella Publications.
  • Ptolemy (1822). Ptolemy's Tetrabiblos or Quadripartite: Four Books of the Influence of the Stars. Translated by J. Ashmand. London: Davis and Dickson.

Further reading[edit]

External links[edit]

  • Decan meanings, from Three Books of Occult Philosophy by Henry Cornelius Agrippa and Astrolabium Planum by Johannes Engel.
  • 3rd Decan Aries Talisman Example of decan talisman using traditional astrology.