A time for everything

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Dating of transits

Interpreting transits involves a refined artistic and creative approach to adapt planetary symbolism to the event description. On the other hand, dating events involve a seemingly mundane assumption, namely the occurrence of an aspect between transiting and transited planets that establishes the event’s timing. However, things are not as straightforward as they appear.

In the event of an isolated transit, an infrequent occurrence indeed, the assumption of its exact timing is beset by a range of factors. Given its rarity, the event in question is unlikely to merit significant attention. Further, the event may occur prior to or after the formation of the exact aspect. In most cases, multiple transits arise on one or more birth chart points. The interpretative hierarchy to be adopted in such circumstances has already been discussed in the preceding paragraph. Still, the search for the event’s timing is complicated by multiple potentially significant transits distributed over an extended period. The following rules seek to clarify some practices regarding transit dating.

The transit of a slow planet is generally dated by the transit of a fast planet that approximately coincides with it.

In this case, the transit of a fast-moving planet can strengthen the nature of a slow-moving planet’s transit and help narrow down the window of time in which the transit occurs. The slow-moving planet’s influence can last for several months, and the Sun and Mars primarily, with Mercury and Venus secondarily, play a crucial role in dating. This principle applies to the transits of isolated fast planets and, to some extent, to multiple transits by fast planets.

We cannot properly speak of an “orbit” of influence in the case of transits.

The classical rule is that the range of influence of transits is directly proportional to the speed of the planet and the aspect type being formed (maximum for conjunction and opposition, minimum for sextile and minor aspects). However, as we have previously noticed, the transit of a single planet alone cannot provide meaningful insights unless the transits of other fast and slow planets are considered, or the nature of the events and the symbolism of the transit are considered as well. It is essential to bear in mind that the transit orbit depends not so much on the timing of the transit itself but on the related event, which often takes a long time (psychologically speaking) to mature and become discernible. In this regard, the temporal vagueness introduced by the concept of “orbit” can be replaced by the search for periodic transits that can help to locate the event more accurately. Translating the orbit of transit from the temporal to the psychological level would also allow us to explain those instances where epochal events do not correspond to significant transits but rather to psychological changes that take time to reach their peak and develop noticeable consequences. As for the use of periodic transits, it should be noted that, when examining a reasonably long period, we may have several dates for the same event; however, each of these dates is precisely defined and clearly indicates the day on which the event may occur.

When multiple transits indicate a single event, the date of the event is determined by the moment at which the average orbit of the transiting planets comes closest to zero.

This technique is particularly relevant when multiple planets transit the same point on a birth chart. The method involves several steps, beginning with calculating the longitudinal distance between the transiting planet and the exact moment of transit. The longitude of the transiting planet is assumed to be calculated in ephemeris time at midnight. An algebraic attribute is then applied to the result obtained, with a minus sign indicating that the planet has yet to transit the exact aspect and a plus sign indicating that it has already done so. This operation is repeated for all planets involved in the transit. The results are then added algebraically, with positive degrees added and the sum of negative degrees subtracted from the total. Finally, the average is obtained by dividing the number obtained by the number of planets used in the calculation. The result represents the average of the angles. For example:

The result derived from the division is positive, indicating that the strength of the transits has surpassed its peak, represented by the value zero.

For the purposes of establishing evidence, it is possible to conduct a reverse procedure to evaluate its accuracy. This involves verifying whether an event occurred on the date corresponding to the mean orbit = 0. Given that planetary motion is not regular, subsequent interpolations are required with the aid of the ephemeris. On the day preceding the calculation date, i.e., 8 August, the planetary average was +4.6′, while on 6 August, it dropped to -30.6′. Consequently, the event is likely to have occurred at approximately 8:52 pm GMT on 6 August. Although precision in time is not essential due to the numerous variables that can invalidate the calculations (e.g., incorrect position of the natal planet, precession of the equinoxes, etc.), verifying the time data in specific case studies may be beneficial.

Calculation of the hourly data

To compute the hourly data, we employ a space-time equation. Assuming that the planetary average covers a distance of 35.2′ (30.6′ + 4.6′) in x hours over 24 hours (1440m), we can infer that it will cover an arc of 30.6′ in the period extending from 0 hours on 6 August until the time when the average orbit equals 0. Thus, solving for x, we find that 1440 x 30.6 / 35.2 = 1252m, corresponding to 20 hours 52 minutes.

When two natal planets are in aspect to each other and receive a transit aspect, the culmination of the event’s influence occurs either when the transiting planet is in exact aspect to each of the two natal planets or when it is halfway through the phase arc of the two transits.

In the context of a natal astrological configuration, let us consider the trine between Mars positioned at 1° 56′ of Aries and Jupiter placed at 5° 15′ of Leo. The planet in transit forms a first sextile with Mars located at 1° 56′ of Gemini and subsequently with Jupiter at 5° 15 of Gemini. It is, however, probable that the event’s culmination will transpire when the transiting planet is positioned at the midpoint of the two aspects. To determine this point, begin by converting the zodiacal longitudes of the planets under consideration into ecliptic longitudes. Next, add the obtained longitudes and divide the result by two. In our example, this process would result in:

Typically, the midpoint is not deemed equivalent to the actual transit. In the aforementioned example, the transiting planet is regarded as being in conjunction when at the midpoint of the two natal factors. Thus, it is interpreted as being in conjunction for all intents and purposes. If the transiting planet were opposite the midpoint between two planets in a trine, it would give rise to opposition on an interpretative level and, on a horoscope level, a grand trine. In some instances (when the aspect between two planets is formed in the eastern hemicycle), the midpoint falls in the longest arc produced by the two planets. Generally, it is preferred to take the midpoint of the shortest arc (considering the sign opposite to the one obtained). However, from an interpretative perspective, this does not make any difference.

Correction for the precession of the equinoxes

The zodiac utilised nowadays is called the Tropic Zodiac, named after the Greek term tropikós, which signifies the circle of the Sun’s revolution. This zodiac circle is centred upon the seasonal partition of the ecliptic. The starting point of the zodiac is the zero degree of Aries or vernal point (from the Latin vernalis, spring), which is the spot where the ecliptic and the celestial equator meet during the spring equinox. Because of the gravitational pull of the planets and the Moon, the vernal point experiences a retrograde movement of approximately 50.25″ per year. This causes a shift in alignment with respect to the fixed constellations of about 25° [1]. The precession motion takes 25,920 years to complete and is known as the Great Year.

In this particular context, the question at hand is not about selecting a zodiac. Still, instead, it is about determining the feasibility of considering precession while calculating the dating of events. As a person ages, the variance between the two zodiacs becomes substantial, with a difference of 1° after 72 years. For instance, calculating the solar return at the age of 36 reveals that a tropical solar return differs from a sidereal return by up to 12 hours, which completely alters the interpretation. Some astrologers assert that transit or solar return positions are acceptable with both zodiacs, but they serve different purposes, which seems to be a reasonable explanation. Below is the calculation for correcting transit positions:

  • Multiply the individual’s age by 5.
  • Divide the obtained result by 6.
  • Subtract the final value from the current positions of the transiting planets.

Consider a person who is 35 years and six months old. In such a case, the calculation is as follows: (35.5 x 5) / 6 = 29.58′. This is the value to subtract from the transit positions.


[1] The phase shift of the zodiac signs in relation to the fixed constellations is a matter of debate in what is defined as Zodiac eras. However, this particular issue does not impact the accuracy of our calculations.

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