Solar arc direction is one of the oldest predictive techniques in astrology. Solar arc is defined as the difference between the position of the progressed Sun and natal Sun on any particular day. This arc is then added to every planet and point in the chart. The arc is approximately equivalent to the individual's age. However, note that a person born in the summer will have a solar arc that is somewhat less than their age and, conversely, a winter-born individual's solar arc will be greater than their age. When a Solar arc directed planet makes an aspect, especially a hard aspect, to a natal planet, some event or transition is likely to occur. This is more so the case when there is a transit activating the point as well. While solar arc is the most common direction used, any planet or point in the chart may be the basis for a direction. You can have a Venus-arc directed chart, vertex-arc directed, ascendant arc directed, etc. The Sun is most widely used because it connects the individual to the other planets.

Using Solar Arcs Like Secondary Progressions

There are two ways of using solar arcs. Some astrologers treat them much like progressions, noting when solar-arc planets enter new houses or signs, and when they make aspects to natal planets.

When you use aspects from solar-arc-directed planets in this way, one peculiar thing happens. Around the age of 30 each of the solar-arc planets and other points in the chart makes an exact 30-degree aspect to its own position at birth. Similarly, around age 45 all the solar-arc planets are in a 45-degree aspect to their own natal position, around age 60 they're in a 60-degree aspect, etc. People born in the winter, when the Sun moves about 61 minutes of arc per day, reach these points a little before these ages. People born in the summer, when the Sun moves about 57 minutes per day, reach them a bit after these ages, with the difference getting greater as they grow older.

So what does it mean to have a day when all your solar-arc planets and other points are making the same aspect to their natal positions? It would certainly cancel out the effect of the individual aspects. Instead, it's as if, for a brief time, your natal chart is operating at double-strength. The quality of what you're feeling on these occasions may have to do with whether the aspect is an easy (sextile) or stressful (semisquare or square) one, and with the major transiting events that are happening just before or after.

About the 30-degree solar arc aspect -- in Astrolabe's Professional Forecaster Report, Bruce Scofield says, it "comes a year or two after your Saturn return, a major transit in everyone's life when people are challenged to define who they will be as an adult. It also comes just after the trine of transiting Uranus to its natal position, which marks a break with the past and an occasion to define one's own individuality. . . . While [the 30-degree solar arc aspect] is not particularly stressful, it does stimulate awareness of who you are becoming."

In other words, these moments that occur around age 30, 45, 60 and 90 are given to everyone as occasions for pausing to reflect on the chart that they were born with, and what they have done with it thus far.

Using Solar Arcs the Classic Way

The other, more classic, method for using solar arcs is the way they are employed by the adherents of astrological symmetry -- Cosmobiologists and Uranian astrologers. These schools look at the arc openings between every pair of points, even when the openings aren’t any of the standard aspects. They concede that while aspects may have a stronger effect, any other kind of arc opening can also assume importance if it is repeated in the chart.

Cosmobiologists use midpoint combinations, in which the opening between points A and B equals the opening between points B and C. Uranian astrologers also use four-point “planetary pictures,” in which the opening between points A and B equals the opening between points C and D. Whether three or four points are involved, the idea is that wherever there are equal openings, there is a kind of resonance that links all of the involved points together.

As points, you would use all the usual planets, plus the Nodes, Asc and MC. Adding the Uranian planets is entirely optional, and you’ll probably, at least at first, want to leave them out.

However, one other point you might want to add right away to your midpoint and planetary picture combinations is the “Aries Point” or “Vernal Point” -- 0 degrees Aries, or the beginning of the zodiac. This is because a planet’s position in longitude is actually the arc between that planet and the Aries Point. Substituting the Aries Point for one of the points in a two-point combination enables you to investigate single planets as well as pairs of planets. As you will see, this can be useful in forecasting with solar arcs.

Forecasting with Arc Openings

When you’re doing a kind of astrology that deals with arc openings, you use solar arcs in a different way. Instead of considering where the solar-arc-directed planets are and how they are aspecting the natal chart, you consider the length of the solar arc itself. Whenever the length of the solar arc becomes equal to the length of the arc between two natal points, it “sets off” an interaction between those points. In other words, at certain times in life, the potential link between those two points “comes due” by solar arc. In addition to pairs of points coming due, single points can come due when the solar arc becomes equal to the arc between that point and the Aries Point.

All this gives you a very simple and effective way of seeing the course of a person’s whole life. As the years go by, the ever-increasing solar arc sets off every pair of points in the chart in a succession that is unique to each person. You can easily trace this succession by printing out a “difference sort” (which in Solar Fire’s Reports 3 menu>Current Chart is called a “Difference Listing” -- just scroll down the menu of choices in the upper right-hand corner, and you will find it). This lists the arc between every pair of planets in the chart, and sorts the pairs of planets beginning with the shortest arc and ending with the longest. Knowing the length of the solar arc at various ages, you can simply go through the list from beginning to end, ticking off each planetary pair at the ages when it becomes due.

By default, Solar Fire’s Difference Listing shows the arcs between all the pairs. To see the arcs for individual planets, you’ll need to add the Aries or Vernal Point to your Difference Listing. First select Reports menu, and then click “Vernal Point Off” so that it will say “Vernal Point On” the next time you open this menu. Then a point called “VP” will be added to your Difference Listings. Any arc in the listing that involves a planet and the VP will actually be the arc for the individual planet.

To interpret the meaning of each pair of points, you can refer to standard aspect meanings, but since you’ll usually be dealing with arc openings that aren’t any standard aspect, you’ll generally need to edit out the qualities (like “easy” for trines, “difficult” for squares, etc.) that would be contributed by the type of aspect. It helps to have a manual that was written with this kind of solar-arc technique in mind. Ebertin’s Combination of Stellar Influences is excellent. It was written for Cosmobiologists and includes all two and three-point combinations of the standard planets, MC, Asc and Node. Because it discusses three-point combinations, it’s a useful interpretation cookbook for many types of astrology. Witte and Lefeldt’s Rules for Planetary Pictures was written for Uranian astrology, and besides the standard points includes the Uranian hypothetical planets. Because it provides an alternative take on the interpretations, it can be nice to have even if you don’t intend to use the hypothetical points.

Recurrences of Solar Arc Contacts

A planetary pair can come due more than once in a lifetime. First of all, every pair of points on a circle involves two arc openings -- the arc from A to B, and then, continuing around the circle, the arc from B back again to A. In addition, astrologers who use the 90- degree dial note when the solar arc connects a natal planet with a point that is in a hard aspect (like 90 or 180 degrees) to the other natal planet. (This is why, when using a Difference Sort listing, it’s useful to select a 45- or 90-degree modulus, so that you’ll see these hard aspects to the solar arc points.) Also, arc openings between points work in octaves, so that a pair of points can also come due when the solar arc gets to both half and twice the arc between the two natal points.

Since solar arcs can set off a planetary pair a number of times during someone’s lifetime, there are likely to be recurrences of the themes signified by these two points. Looking back at what happened under previous solar-arc contacts involving the same points can be very helpful in understanding what is currently going on in the person’s life.

Using Solar Arcs in Relationship Forecasts

You can also use solar arc lengths to trace the developments in a relationship. Seeing how one person’s current solar arc is setting off the planetary pairs in the other’s natal chart is an easy and effective way to uncover the issues that one partner is currently experiencing as the result of being in a relationship with the other.

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