Predicting Orbital Events of the Moon

A MATLAB script named lunar_events that can be used to compute important orbital events of the Moon's motion.

This submission is a MATLAB script named lunar_events that can be used to compute important orbital events of the Moon’s geocentric motion. The motion of the Moon is modeled using the JPL DE430 binary ephemeris (de430.bsp). This script also uses routines from the MICE software suite to read and evaluate this ephemeris.

The MICE routines and other ephemeris files are available at naif.jpl.nasa.gov/naif/toolkit_MATLAB.html. MICE is a MATLAB implementation of the SPICE library created by JPL.

Using a combination of one-dimensional minimization and root-finding, the lunar_events MATLAB script computes the following geocentric characteristics of the Moon’s orbital motion.

• apogee and perigee
• minimum and maximum geocentric declination
• user-defined geocentric right ascension
• user-defined geocentric declination
• user-defined true anomaly
• minimum and maximum orbital eccentricity
• nodal crossings

Script options 1, 2, and 6 are minimum and maximum conditions of the lunar orbit. The nodal crossings correspond to times when the ascending or descending Moon crosses the Earth’s equatorial plane.