Key to Geocentric Ephemeris of the Moon


An ephemeris is a table of values that gives the positions of astronomical objects in the sky over a range of times, while geocentric means "as seen from Earth's center." The following table is a key to the geocentric ephemeris of the Moon and includes a description of each column in these tables.

Key to Geocentric Ephemeris of the Moon
Column Heading Definition/Description
1 Date
(0 UT)
Calendar Date (Gregorian).
All ephemeris positions are for 00:00:00 UTC
(Coordinated Universal Time).
2 Apparent
R.A.
Apparent Right Ascension of the Moon for the true equator
and equinox of date (hours, minutes, seconds).
3 Apparent
Declination
Apparent Declination of the Moon for the true equator
and equinox of date (degrees, arc-minutes, arc-seconds).
4 Distance
to Earth
Distance of the Moon from Earth (kilometers).
5 Hor.
Par.
Horizontal Parallax
Shift in the Moon's apparent position from two points on Earth separated by a perpendicular distance of one Earth radius.
6 Ang.
Diam.
Apparent Angular Diameter of the Moon (arc-seconds).
7-9 Libration
l - b - c
Lunar Libration
Selenographic or lunar coordinates of the central point
of the Moon's disk (degrees) measured in
l (longitude), b (latitude) and c (position angle).
10 Sun
Colng
Solar Colongitude
Selenographic or lunar longitude of the
morning/sunrise terminator (degrees).
11 P.A.
Limb
Phase Angle of the Lunar Limb
Position Angle of the midpoint of the Moon's bright limb,
measured eastwards (counter-clockwise) on the sky from the celestial north point of the lunar disk (degrees).
12 Phase
Age
Age of the Moon, measured from the instant of New Moon (days).
13 Phase
Illum.
Phase Illumination
Fractional area (or diameter) of the Moon's apparent disk
illuminated by sunlight.
14 Solar
Elong.
Solar Elongation of the Moon.
Defined as geocentric angular position of the Moon
with respect to the Sun (degrees).
'E' is east (evening sky) and 'W' is west (morning sky).
15 Lunar
Events
A list of major lunar events and the corresponding times (in UTC) where:
NEW, FIRST, FULL, LAST - phases of the Moon
APO, PERI - Moon at apogee (APO) or perigee (PERI)
A.NOD, D.NOD - Moon at ascending (A) or descending (D) node
MAX.N, MAX.S - maximum northern (N) or southern (S) declination