The whole chart moved by one figure
Solar arc takes the distance the progressed Sun has travelled since birth and adds it to every natal position. Everything advances by the same amount, roughly a degree per year of life.
That uniformity is the technique. Because every body moves identically, the aspects between natal bodies survive untouched: a natal Sun square Saturn is still a square after fifty years of direction. What changes is the chart's relationship to the angles and to the natal positions themselves.
Why practitioners use it
Simplicity and timing. Because the arc is about a degree a year, a directed body reaches a natal point at a calculable age, and the contact is exact for roughly a year either side.
That gives sharper timing than transits from the outer planets, which can hover within orb for years. Solar arc contacts arrive, are exact, and pass, which makes them the technique of choice when the question is when rather than what.
| Technique | Timing precision | What it moves |
|---|---|---|
| Transits | Days to years, depending on the body | Where planets actually are |
| Secondary progression | Each body at its own rate | The sky shortly after birth, on a slow clock |
| Solar arc | About a year per contact | The whole chart, uniformly |
What to look for
Contacts to the angles first. A directed planet reaching your ascendant or Midheaven is the configuration solar arc is most used for, and the result lists those separately.
Then directed bodies reaching natal bodies. A directed Saturn arriving at a natal Sun is a specific and datable event, and it happens once in a lifetime at a calculable age.
Conjunctions carry most of the weight in this technique. Squares and oppositions are read; the softer aspects are usually given less attention than they would be in transit work.
The angles problem
Directed contacts to the ascendant and Midheaven are the most cited use of the technique and the most fragile, because both depend entirely on the recorded birth time.
Four minutes of error moves the angles a degree, which in solar arc terms is a year. A chart with an approximate birth time will produce directed angle contacts at the wrong ages, and no amount of care in the calculation fixes that.
If your birth time came from a family recollection rather than a certificate, read the directed planets and hold the directed angles loosely.
How the arc is calculated
The progressed Sun's position at the chosen date, minus the natal Sun's position. That difference is the arc, and it is added to every natal longitude.
Because the Sun moves slightly faster in some parts of the year than others, the arc is not exactly one degree per year. The calculator computes it from the actual progressed position rather than assuming an average, and the figure is printed at the top of the result.
Solar arc against progressions
They share a starting point and diverge immediately. Secondary progression moves each body at its own rate, so the progressed Moon covers thirteen degrees a year while Pluto barely moves. Solar arc moves everything by the Sun's arc.
The practical consequence is that solar arc brings slow planets into contact with natal points at readable ages, which progressions never do. A directed Pluto reaching a natal Venus is a solar arc event; in secondary progression Pluto would take centuries to get there.
Most practitioners use both. The progressed chart covers the other half.
What it cannot do
Name an event. Solar arc gives you a date and a configuration, and what happens on that date is not in the chart. Directions are a timing technique, not a description of content.
Common questions
What is solar arc direction?
Every natal position advanced by the distance the progressed Sun has travelled, roughly a degree per year of life. The whole chart moves by one figure.
Do the aspects survive?
Yes. Because everything moves identically, aspects between natal bodies are untouched. What changes is the chart's relationship to the angles and to the natal positions.
Why use it instead of transits?
Timing. A directed contact arrives, is exact for about a year, and passes. Outer planet transits can hover within orb for years, which is vaguer.
How is it different from progressions?
Progressions move each body at its own rate, so slow planets barely move. Solar arc brings Pluto to a natal Venus at a readable age, which progression never would.
How reliable are directed contacts to the angles?
Only as reliable as your birth time. Four minutes of error moves the angles a degree, which in solar arc is a year.
Can it predict an event?
No. It gives a date and a configuration. What happens on that date is not in the chart.