➚ Free Solar Arc Directions Calculator

Umbriel's free solar arc calculator advances your entire chart by the Sun's own progressed motion — roughly a degree a year, so a directed planet meeting a natal point marks an age you can name. Free, no account.

• What you'll needBirth date, time and place
• What you getEvery point advanced by the arc, and the contacts it makes to your natal chart for any date
• CostFree — no account required

Solar arc takes one number — how far the Sun has progressed since your birth — and moves everything by it. Not each planet at its own speed: the whole chart, by the same arc.

Because it is one arc applied uniformly, the chart keeps its exact shape. Every natal aspect survives untouched. What changes is where the whole figure now falls against the chart you were born with, and the contacts it makes on the way.

The arc runs at roughly a degree a year, which is what makes the technique legible: a directed Mars arriving at your natal Saturn marks an age, and you can read forward or back from it.

It is often set beside secondary progressions, which move each body at its own rate. Progressions describe an unfolding; solar arc marks events against the chart. Umbriel has both, and they answer different questions.

Because everything moves together, the technique is unusually easy to check by eye: the whole directed chart should sit at the same angular distance from the natal one at every point. If two directed positions differ from their natal counterparts by different amounts, something is wrong with the arithmetic rather than interesting about the chart.

The Sun's secondary-progressed motion is measured from birth to the chosen date — one day of ephemeris time per year of life, including the fraction — and every point in the chart is then advanced by that single arc. Because it is one arc applied to everything, the chart keeps its own shape exactly: every natal aspect is preserved, and what changes is where the whole figure now falls against the natal wheel. The arc runs at roughly a degree a year, which is what makes the technique legible — a directed planet reaching a natal point marks an age you can name, and the same arithmetic means an hour of error in the birth time matters far less here than it does for progressed angles. The arc itself is printed in degrees rather than hidden inside the result, so the arithmetic can be checked by hand: subtract the natal Sun from the progressed Sun and every other directed position should differ from its natal counterpart by exactly that figure. Directed angles are shown only when the birth time supports them, on the same principle the progressions page uses.