Function getMercuryPosition

getMercuryPosition(jd: number, options?: EphemerisOptions): PlanetPosition
Calculates the geocentric position of Mercury.
Parameters
- jd: number
  Julian Date
- options: EphemerisOptions = {}
  Optional calculation parameters
Returns PlanetPosition
Mercury's position including longitude, latitude, distance, and speed
Remarks
Mercury's position is calculated using VSOP87-derived series from Meeus. The calculation provides heliocentric coordinates which are then converted to geocentric ecliptic coordinates.

Accuracy: ±1 arcminute for years 1800-2200.
Example
```
import { getMercuryPosition } from 'celestine/ephemeris';

const jd = 2451545.0; // J2000.0
const mercury = getMercuryPosition(jd);
// mercury.longitude ≈ 250.2° (Sagittarius)
// mercury.isRetrograde depends on orbital position
```
Source
Meeus, "Astronomical Algorithms", Chapter 33
- Defined in ephemeris/planets/mercury.ts:484