Function calculateSolarArc

calculateSolarArc(birthJD: number, targetJD: number): number
Calculate the solar arc for a given birth and target date.
Parameters
- birthJD: number
  Julian Date of birth
- targetJD: number
  Julian Date to calculate arc for
Returns number
Solar arc in degrees
Remarks
The solar arc is the difference between the progressed Sun position and the natal Sun position. For secondary progressions, this is approximately 1° per year of life.
Example
```
const birthJD = 2451545.0; // J2000.0
const targetJD = birthJD + 30 * 365.25; // 30 years later
const arc = calculateSolarArc(birthJD, targetJD);
console.log(arc); // ~30° (about 1° per year)
```
- Defined in progressions/solar-arc.ts:47