Solar arc: the clock that advances one degree a year
In solar arc every planet is advanced by the same arc the progressed Sun has travelled — roughly one degree per year. Its meaning only appears when compared to the natal chart.
Calculate for freeSolar ArcIn solar arc directions every planet in the chart advances by the same amount: the arc the progressed Sun has travelled since birth, which is roughly one degree per year of life. At forty, all your planets sit about forty degrees ahead of their natal positions.
The critical rule: a solar arc planet is never interpreted alone. Its meaning is born the moment it contacts a natal planet or angle. Solar arc Saturn sitting in Libra says nothing by itself; conjunct your natal Sun, it makes that year one of responsibility, maturation and building serious structure.
What to look at in a solar arc
- Exact aspects from solar arc planets to natal planets — keep the orb under 1 degree.
- Solar arc contacts to natal angles (ascendant, MC, IC, DC) — these deliver the most concrete events.
- 0 degrees: the opening of a new cycle, a story starting from scratch.
- 29 degrees: a cycle closing, urgency and pressure to complete.
- Sign changes: when a planet crosses into a new sign by solar arc, the tone of that life theme changes completely.
Why the orb is so tight
Because solar arc moves about one degree per year, a 1-degree orb equals roughly one year. That makes it one of astrology's sharpest timing tools: the year the aspect perfects is the year the theme enters your life. Using a wide orb destroys the precision.
Solar arc plus transits
Solar arc gives the year, transits give the month. If solar arc Uranus squares your natal Moon, expect a sudden shift in emotional life that year; the week the Moon or a fast planet triggers it tells you which month it breaks. Layer the two techniques and the timing becomes remarkably clear.
Frequently asked questions
How is solar arc calculated?
You find the arc the progressed Sun has travelled since birth and add that same amount to every planet in the chart, which works out to roughly one degree per year.
Can solar arc be read on its own?
No. Solar arc is always read against the natal chart; its meaning comes from the contacts it makes to natal planets and angles.
What is the difference between solar arc and progressions?
In progressions each planet moves at its own speed; in solar arc all of them advance by the same arc. That makes solar arc sharper and more event-driven.
What orb should be used for solar arc?
One degree or less. Since solar arc advances about a degree per year, a 1-degree orb corresponds to roughly a one-year window.