Fast and Easy Primary Directions

Primary directions are one of the oldest predictive techniques in Western astrology. In many ways they are like the dashas of Indian astrology in that they identify periods during which certain the planets involved tend to be active in the native’s life. Although primary directions were widely used in classical and traditional astrology, they fell out of popularity in modern times because they were considered difficult to calculate in comparison with the more recent secondary progressions (introduced by Placidus in the 17th century).  Modern software programs have now made primaries more accessible and they are regaining popularity.

The fact that modern computer programs often have a “chart animate” feature allows the user a quick and easy way to visualize how the directed chart will appear as the client ages.  The rule of thumb in primary directions is that symbolically each degree on the Equator (measured in Right Ascension) that crosses the MC is equivalent to one year of life.  Because it takes almost 4 minutes for one equatorial degree to pass over the MC, every 4 minutes of ordinary clock time added to the birth time advances the chart by about one year of life in Ptolemy’s system of primary directions.

The basic premise of primary directions is that the manner in which the chart unfolds due to the Earth’s rotation in the first six hours after birth correlates symbolically with how the native’s life will develop during the first 90 years of life on this planet.

By using the “chart animate” feature, we can advance a birth chart by 4 minutes of clock time for every year of life to get a close estimate of how the primary directed chart will look on each subsequent birthday. The chart thus produced will advance the zodiacal positions of the planets slightly from their birth positions but this secondary motion is generally insignificant, except for the Moon which travels about 3 degrees every 6 hours after birth. Because each hour corresponds to 15 equatorial degrees, six hours equals 90 degrees of Right Ascension, which is equivalent to 90 years of life in primary directions.

The most important primary directions are the conjunctions of planets to the horizon (Asc) or meridian (MC).  Also important are the years when there is a change of sign on the Ascendant or MC, or for that matter on any of the house cusps if you use quadrant houses.  Finally, if you set up the chart to show the terms or bounds, you can see how the system of “distributions” unfolds over time as the bounds of the natal signs below the ascendant rise to the horizon during your lifetime. Planets that closely aspect the directed ascendant in a given year are also significant. For most primary directions I use an “orb” of influence of about 6 months before and after the direction becomes exact.


Two Technical Notes

A. Sidereal vs. Mean Solar Time

Astronomers commonly use two types of time: 1) sidereal time, measured against the fixed stars and 2) mean solar time (ordinary clock time) based on the movement of the Earth on its orbit around the Sun. From our geocentric perspective, the Sun travels in a great circle called the ecliptic, whose intersection with the Celestial Equator occurs at the two Equinoctial Points (0 Aries and 0 Libra) and is the basis for the tropical zodiac.

Because the Earth rotates from west to east, the 0 Aries point appears to move around the Celestial Equator in a complete circle every 24 hours of sidereal time, as measured against the fixed stars. In other words,

  • A sidereal day measures the Earth’s rotation relative to the fixed stars rather than to our Sun.
  • As a result, the stars always appear in the same place in the sky at the same sidereal time each day.
  • 360 equatorial degrees = 24 sidereal hours (a sidereal day). Note that sidereal days, unlike solar days, are equal in duration.
  • 15 equatorial degrees = 1 sidereal hour
  • 1 equatorial degree = 4 sidereal minutes
  • 1 equatorial minute = 4 sidereal seconds

Comparison of Sidereal Days and Mean Solar Days in an Image By Xaonon – Own work, CC BY-SA 4.0,

Due to the Earth’s elliptical orbit around the Sun, solar days vary slightly in their duration. At certain times of year the Sun travels a bit faster or slower than at other times, so that solar days are not uniform throughout the year. Because astronomers prefer that days in common usage be of equal duration, they use mean solar days, based on the average rate of the Sun around the ecliptic.

Astronomers thus speak of the Mean Sun (“mean” meaning average, not cruel or unkind), which is a hypothetical point that travels around the ecliptic at the average rate of motion of the real Sun. A mean solar day is then defined in terms of the motion of the hypothetical Mean Sun rather than the actual Sun. Mean solar days have the mathematical advantage that they are all of equal duration. Important implications of using the Mean Sun include:

  • The mean tropical year has a duration of 365.2422 mean solar days.
  • The mean solar day of 24 hours on the ordinary clock (not sidereal time) is the interval of time it takes for the hypothetical Mean Sun to travel from the meridian (Noon) of a location on one day to the meridian (Noon) of the same location on the next day.
  • In other words, a mean solar day is measured from Noon to Noon (a daily solar return), that is, the time it takes for the mean Sun to return to its highest point in the sky.
  • During the 24 hours of a mean solar day, the Earth spins once on its axis once and then a bit more as the Sun also advances about one degree along the ecliptic.
  • In other words, during a mean solar day the Earth makes one complete rotation on its axis and also travels about 2.5 million kilometers along its orbit around the Sun.
  • As a result, the same stars appear to rise about 4 minutes earlier in the sky each day. For example, if Spica rose at 7 pm today, it would rise about 6:46 pm tomorrow, and so on.
  • Because a sidereal day only measures exactly one rotation of the Earth, whereas the mean solar day measures both a rotation of the Earth and its movement along the orbit around the Sun, 365.24 mean solar days = 366.24 sidereal days.
  • In other words, it takes an additional 3 minutes 57 seconds of sidereal time for the Mean Sun to reach the meridian during a mean solar day of travel.
  • Thus, 1 sidereal day = 23 hours 56 minutes 4 seconds of ordinary clock time = 360 degrees on the Equator = one rotation of the Earth.
  • Dividing 23 hours 56 minutes 4 seconds by 360 degrees in a circle gives a result of 3.989 minutes per equatorial degree, which is equivalent to one year of life in primary directions according to Ptolemy.

B. An alternative to Ptolemy’s key for primary directions: If we symbolically equate one rotation of the Earth on its axis (a sidereal day) to one year of life, then dividing the length of the sidereal day (23.934444 hours) by the number of days in a year (365.24219), we get 3.931819596 minutes crossing the MC being equivalent to one tropical year of life. A sidereal day is used because it measures the time the Earth takes to rotate exactly once on its axis relative to the stars and its duration is almost four minutes shorter than the solar day because of the Earth’s orbital motion around the Sun. This alternative approach follows the reasoning of 16th century astrologer Valentine Naibod.

If each rotation of the Earth is equivalent to one tropical year of life, then (rounding to 4 digits) each 3.9318 minutes after birth corresponds to one year of life.


An example will make this procedure clear. Let’s consider the chart of actress Shirley Temple. Her birth data, rated AA, from is

23 April 1928 at 21:00 (= 9:00 PM )
Place Santa Monica, California, 34n01, 118w29
Timezone PST h8w (is standard time)

Here is her natal chart:


Let’s consider a major health crisis.  In November of 1972 at the age of 44.532 years (03 November 1972) she was treated for breast cancer with a radical mastectomy.  The possibility of surgery for breast cancer is indicated in the “natal promise” of her chart in that she has Pluto in Cancer (breasts) in the 8th (life-threatening experiences) in close square to 6th house ruler Venus in the sign of her detriment Aries.  One might expect that during the period when Pluto is activated by primary direction, that is, when Pluto arrives at the western horizon by primary motion, this natal promise might manifest.

To direct her chart at a rate of one degree of R.A. over the MC equals one year of life, we can multiply 4 minutes of clock time for year year of life by 44.53 years, which gives the result 178.09 minutes.  If we use the formula that one rotation of the Earth equals one year of life, we multiply 3.93182 minutes times 44.532 years, which gives a result of 175.09 minutes to be added to the birth time.

Her birth certificate says she was born at 9:00 PM.  To this time we add 175.09 minutes (which is 2 hours and 55 minutes and 5 seconds, so the the “primary directed birth time” for age 44.532 years becomes 11:55:05 PM.  Here is the chart set for this adjusted birth time:


The above chart is basically the natal chart advanced by primary direction (at the Naibod rate of 3.93182 minutes crossing the MC equals one year of life) to age 44.53 when she had her breast surgery.  Pluto, which occupies the Cancer 8th house (Pluto-Cancer-8th suggests radical breast surgery), is now on the Descendant and opposed to the directed Ascendant, which lies in the Venus bound of Capricorn at 14 Cap 48.  Hence, by the method of distributions, the divisor for this period of her life is a fallen Venus in Aries, and if she were born very slightly after 9 PM its participating planet would be Pluto which lies in opposition.  The symbolism fits well with the natal promise of surgery for breast cancer, and the timing by primary direction is extremely close to the date of the surgery.

Finally, here is a list of her Placidean zodiacal primary directions calculated in Solar Fire for the year 1971, using Ptolemy’s key of one degree of R.A for each year of life:


There is a strong emphasis on Pluto in Cancer in the 8th house this year, which begins with the Sun by primary direction forming a trine to natal Pluto.  As you can also see in this list, Pluto came to the horizon in July of 1972, about four and a half months before the radical mastectomy.  This corresponds to the period of detection of the breast cancer, the initial surgical removal of the lump which she discovered in May of 1972, and further consultations with her doctor to decide on the best final treatment.

She discovered a lump in her breast six months before the surgery when Jupiter by primary direction was square in Moon’s Nodes, and at that time she underwent a simple mastectomy.  The radical mastectomy surgery occurred on Friday 3 November 1972 when the direction of Venus (ruler of the natal 6th of health issues) trine the Moon (ruler of the 8th of life-threatening conditions and surgery) came to its perfection.

The image below is from the program Stellarium.

Shirley Temple birth horizon

This is the sky at the moment of Shirley Tempe’s birth (9 PM). Natal Pluto will set on the western horizon about 11:56 PM, which is 176 minutes after she was born. Dividing 176 minutes by about 4 minutes (for each equatorial degree that crosses the MC) gives a result of 44 degrees of Right Ascension, which corresponds to 44 years of life. She was diagnosed with breast cancer at age 44.


About Anthony Louis

Author of books about astrology and tarot, including TAROT PLAIN AND SIMPLE, HORARY ASTROLOGY, and THE ART OF FORECASTING WITH SOLAR RETURNS.
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3 Responses to Fast and Easy Primary Directions

  1. Jon says:

    What iteration based on a target date is ideal for project completion (e.g., Lets say target date is 11/23/2019). Today is 07/21/2019. What is the algorithm leading up to target date for working and attempting work on said project. Some suggest that squares are indicative of change (i.e., what you start now will manifest 6 months from now). Is there a fixed pattern or purely set out by relative motion of planets?

  2. Jon, I think you are referring to electional astrology, which is a complex topic and requires a good understanding of the natal chart and its promise, as well as the current and upcoming astrological conditions and how they relate to the natal chart. There is no simple answer.

  3. Jon says:

    So . . . there is an intersection between thoughts and biology, but none easily ascertainable. Interesting!

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