Function toJulianCenturies

toJulianCenturies(jd: number): number
Convert Julian Date to Julian Centuries from J2000.0 epoch

The J2000.0 epoch is January 1, 2000, 12:00 TT (JD 2451545.0). Most planetary position formulas use T as the time parameter.
Parameters
- jd: number
  Julian Date
Returns number
Julian Centuries from J2000.0 (can be negative for dates before 2000)
Example
```
// J2000.0 epoch
toJulianCenturies(2451545.0)  // Returns: 0.0
```
Example
```
// One century after J2000.0
toJulianCenturies(2488070.0)  // Returns: 1.0
```
Example
```
// One century before J2000.0
toJulianCenturies(2415020.0)  // Returns: -1.0
```
- Defined in time/julian-centuries.ts:35