Here is some basic data about the Moon:

• Mean distance from Earth= 384401 km

• Extreme range 356400406700 km

• Mean horizontal paralax 3422.60"

• Eccentricity of orbit = 0.0549

• Inclination of orbit to ecliptic = 5°08'43"

• Sidereal period (fixed stars)= 27.321661 ep. days

• Synodical month (New Moon to New Moon) = 29.5305882 ep. days

• Anomalistic month perigee to perigee) = 27.5545505 days

• Tropical month (equinox to equinox) = 27.321582 days

• Nodical month (node to node) = 27.212220 days

• Period of Moon's node (nutation, retrograde) = 18.61 tropical years

• Period of rotation of Moon's perigee (direct) = 8.85 years

• Moon's sidereal mean daily motion = 13°.176358

• Mean Transit interval = 24h 50.47m

Main periodic terms in the Moon's motion:

• Principal elliptic term in longitude 22639"sin g

• Principal elliptic term in latitude 18461"sin u

• Evection = 4586"sin (2D-g)

• Variation = 2370"sin 2D

• Annual inequality = -669"sin g'

• Parallactic inequality = -125"sin D, where g = Moon's mean anomaly, g'= Sun's mean anomaly, D = Moon's age and u= distance of mean Moon from ascending node.

• Inclination of lunar equator to ecliptic = 1°32.5'

• Inclination of lunar equator to orbit = 6°41'

• Mean Moon radius= 1738.2 km

• Moon mass = 1/81.301 mass of Earth

Copyright (c) 1997-99 Michael Erlewine