Celestine API Documentation - v0.2.0
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    Function getMoonPosition

    • Calculates the geocentric position of the Moon.

      Parameters

      • jd: number

        Julian Date

      • options: EphemerisOptions = {}

        Optional calculation parameters

      Returns PlanetPosition

      Moon's position including longitude, latitude, distance, and speed

      The Moon's position is calculated using Meeus' algorithm from Chapter 47, which is based on the ELP-2000/82 lunar theory (simplified).

      Accuracy:

      • Longitude: ±10 arcseconds (~0.003°)
      • Latitude: ±4 arcseconds (~0.001°)

      This is well within our 1 arcminute (0.017°) target.

      import { getMoonPosition } from 'celestine/ephemeris';

      // J2000.0 epoch
      const jd = 2451545.0;
      const moon = getMoonPosition(jd);
      // moon.longitude ≈ 218.32° (Scorpio)
      // moon.latitude ≈ 5.15°
      // moon.distance ≈ 0.00257 AU (~385,000 km)
      // moon.longitudeSpeed ≈ 13.2°/day

      Meeus, "Astronomical Algorithms", Chapter 47

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