Solar Arc Directions: Moving the Whole Chart by the Sun's Arc

← Back to Transits

Solar arc directions move your whole birth chart forward by one amount. At a given age, the astrologer measures how far your secondary-progressed Sun has travelled from your natal Sun. That distance is the solar arc. The same arc is then added to each natal planet (the Sun to Pluto on these pages), so the planets keep their natal spacing and move forward together, roughly one degree for each year of life. Each moved planet is called a directed planet, and directed planets are compared with the natal chart.

Solar arc directions are a separate symbolic directing technique, not a transit. Nothing in today's sky is measured. They sit in the Transits library because they are another way of dividing up a life in time, next to secondary progressions and annual profections.

Calculator note: the free birth chart is an ordinary chart for one date, time and place. It does not automatically generate a progressed chart, a solar arc, directed positions, directed angles or direction contacts from your birth data. You can work out the progressed instant by hand and enter that civil date and time into the same free chart to read the Sun's position, and the method page shows how. The figures on this page were calculated offline with the planetary routines the free chart uses (described on the methodology page); they are not a hidden feature. Ask the Astrologist is not given degrees, arcs or directed positions and is not a solar-arc calculator, though you can tell it what you worked out. The steps are on how to calculate your solar arc directions.

The convention used on these pages

These guides use one working definition, the true solar arc in Tropical ecliptic longitude:

• The arc. Solar arc at an age = secondary-progressed Sun minus natal Sun, measured forward around the zodiac (modulo 360°). The progressed Sun comes from the day-for-a-year rule explained in secondary progressions explained: at age 33 you read the Sun 33 days after the birth instant.
• What moves. The same arc is added to each of the ten natal planets from the Sun to Pluto. The Lunar Nodes, Chiron and Lilith are left out of these guides, and the chart angles are treated separately below.
• One consequence. Under this convention the directed Sun is the progressed Sun. Every other directed planet usually differs from its progressed position.

This is the convention chosen for these pages so the arithmetic can be checked, not the one correct key. Astrologers who use solar arcs make different choices, and the next section shows the most common ones.

Three keys: true arc, Naibod and one degree a year

The "key" is the rule that turns an age into an arc.

• True solar arc (used here) follows the real Sun in the days after your birth, so it reflects how fast the Sun was actually moving then.
• The Naibod key, named after Valentin Naibod, uses the Sun's mean daily motion instead: 0°59′08″ for each year of life, the same for everyone.
• The one-degree key simply adds 1° per year of life.

Because the Sun's apparent speed along the ecliptic is not constant through the year, the true arc runs ahead of Naibod for some charts and behind it for others. Ruben, the fictional example used across these guides (London, 5 January 1993, 12:00, which is 12:00 UT), has a true arc of 33.56° at age 33, against 32.53° by Naibod and 33° by the one-degree key: his January chart runs about 1.03° ahead of Naibod. Lotte, the example on the method page (Utrecht, 27 August 1991), has a true arc of 34.08° at 35 against 34.50° by Naibod: her August chart runs about 0.42° behind. The differences have opposite signs because the Sun was moving at different speeds in the weeks after each birth, not because one key is better.

Since the arc grows by about a degree a year, a difference of 1° in the arc moves the date of a contact by about a year. Another source using another key can therefore date the same contact months or a year away from these pages without either being a mistake.

Two further variants are named here only and not calculated: some astrologers measure the solar arc in right ascension, along the celestial equator, rather than in ecliptic longitude, and converse directions subtract the arc instead of adding it.

Solar arcs and secondary progressions

The two techniques start from the same progressed Sun and then part ways.

Ruben shows the difference at 33. His progressed Sun and his directed Sun are both 18°43′ Aquarius. But his progressed Moon is at 25°52′ Leo, while his directed Moon is at 9°17′ Cancer; his progressed Venus is 4°18′ Aries, his directed Venus 5°12′ Aries. The progressed figures are worked through in how to calculate your secondary progressions.

Because the same arc is added to every included planet, the angle between any two directed planets is the same as the angle between those two planets at birth. A directed-to-directed aspect is therefore just a natal aspect, and the technique's new information is in directed-to-natal contacts. That statement holds for the ten planets moved by the same arc in longitude; it does not carry over to the angles, whose directing methods vary.

How contacts are read

These guides use the five major aspects only: conjunction (0°), sextile (60°), square (90°), trine (120°) and opposition (180°), made by a directed planet to a natal planet.

A ±1° screening window. The examples list contacts within 1° of exact. That is this guide's illustrative screening window, not an Astrologist.com orb, not a rule of the site and not a claim about what every astrologer uses. It is also unrelated to the orbs the free chart uses for natal aspects (see aspect orbs). With an arc growing about a degree a year, a contact spends roughly two years inside a ±1° window: about a year before exact and a year after. Some solar-arc schools also use 45° and 135° contacts and midpoints; these guides do not.

Before and after exact. These pages describe a contact only as before exact or after exact, together with the exact age and an approximate date. Ages are solved from the unrounded calculated positions; positions are shown in degrees and whole minutes like the free chart, so an orb worked from the displayed minutes can differ slightly from the calculated one.

Worked example: Ruben at 33

The age was fixed at exactly 33, his birthday on 5 January 2026, before any contact was looked at, the same age used on the secondary-progressions method page. His progressed Sun at 33 (7 February 1993, 12:00 UT) is 18°43′ Aquarius and his natal Sun is 15°10′ Capricorn, so the arc is 33°33′ from those displayed positions (33.56° unrounded).

The directed column is calculated from unrounded positions and then truncated to the minute. Adding 33°33′ to the displayed natal minutes by hand gives the same positions or one minute less. A natal Mars marked R is still simply moved forward by the arc.

Within the ±1° window at his 33rd birthday:

• Directed Venus sextile natal Moon, 0.51° before exact; exact at 33.51, early July 2026.
• Directed Jupiter sextile natal Uranus, 0.54° before exact; exact at 33.53, mid July 2026.
• Directed Jupiter square natal Saturn, 0.56° after exact; it was exact at 32.44, mid June 2025.
• Directed Venus square natal Mercury, 0.79° after exact; it was exact at 32.22, late March 2025.

The same four contacts under the three keys:

Under the true arc the two sextiles fall in his 34th year and the two squares were already past; under Naibod the two squares fall in his 34th year and the sextiles about a year later. This is a sensitivity to the method chosen, not evidence that one key is right.

Dates use the same convention as the progressions method: the age in years multiplied by 365.2422 days, counted from the birth date, and given only as early, mid or late in the month.

Birth time and solar arcs

The arc itself hardly depends on the birth time. Across Ruben's whole birth date, checked minute by minute with both the natal chart and the progressed Sun recalculated each time, his arc at 33 stays between 33.557° and 33.564°. What changes are the natal positions the arc is measured against, above all the Moon, which moves about half a degree an hour.

• A contact to the Moon is time-sensitive. Directed Venus sextile natal Moon is exact in early January 2026 for a birth at 11:00, early July 2026 at 12:00 and mid January 2027 at 13:00.
• Contacts between slower planets are steadier. With no birth time at all, the same minute-by-minute check across the whole date keeps directed Jupiter sextile natal Uranus inside the window at 33 and exact in mid July 2026 at every minute, and keeps directed Jupiter square natal Saturn inside the window and past exact throughout. Directed Venus square natal Mercury drops out of the window for part of the day, so without a time it stays unresolved.

The rule these pages follow: a contact between two planets other than the Moon can be stated without a birth time only if a check through the entire possible birth-time range keeps the same contact and the same date band. Checking the start and end of the day alone is not enough, and the noon reference the free chart uses for an unknown time is never treated as a birth time. Contacts involving the Moon, houses and angles are not available without a reliable time. How accurate does your birth time need to be? covers the wider question.

Angles

Solar-arc astrologers also direct the Midheaven and the Ascendant, and contacts to and from the angles are often given a lot of weight in their work. The methods for doing this vary, especially for the Ascendant. All of them need a reliable birth time and the numeric degrees of the natal angles, and the free chart shows where the Ascendant and Midheaven fall but does not print their degrees. These guides therefore describe directed angles as a concept only and give no directed-angle figures or contacts to the angles. House placements of directed planets are left out of the worked method for the same reason.

Themes, not events

Solar arcs are symbolic arithmetic, not positions of anything in the sky and not a cause of anything. Astrologers who use them read a contact as a theme coming into focus for a period, with its meaning set by the two planets involved (see planet meanings). A square or an opposition describes a different kind of emphasis from a trine; it does not mark a difficult date. Nothing on these pages predicts an event, a health matter, a relationship outcome, money or a career change.

Some astrologers compare solar-arc contacts with dates of past life changes when testing a doubtful birth time. Birth time rectification describes that practice and its limits; it is an example of how the technique is used, not proof that it works.

Next steps

The working method, with Lotte's chart at 35, the arc subtraction, the directed positions and the exact-age arithmetic, is on how to calculate your solar arc directions. The progressed Sun it starts from is explained in secondary progressions explained and worked out step by step in how to calculate your secondary progressions. For real-sky timing, see how transits work. Start from your natal positions on the free birth chart, and you can ask the Astrologist about solar arcs as a concept or about a directed position you have worked out yourself.

Related articles

• How to Calculate Your Solar Arc Directions
• Secondary Progressions Explained
• How to Calculate Your Secondary Progressions
• The Progressed Moon
• Annual Profections
• Aspect Orbs in Astrology
• Birth Time Rectification