LUNAR LIBRATION

HOW DOES IT WORK

by

DAVID O. DARLING

Shown below are libration plots for months of March and May 2002. As you can see both of these plots are quite different. Each month the lunar libration will change. Very seldom do two plots match up perfectly. These libration plots indicate the phases of the Moon on it since its starting date is on the first of the Month, not on the beginning of Moon's lunation period. Again what this tells you is where the observer would be standing on the lunar surface in order for the Earth to appear at his zenith.  What it also tells you is that if the plot is located on the far west side, as it is on March 21,  the western limb of the Moon is turned toward the Earth, giving the observer a good view of features on that limb.  This is the normal reason lunar observers will use libration plots and it's not generally used for the study of Lunar Transient Phenomena. This is a concept that I developed fifteen years ago when I began my research on this phenomena.  The ephemeris for these plots can be computed by using a computer program developed by Harry Jamieson and is called the Lunar Observer's Tool Kit or by using the U.S. Navel Observatory lunar ephemeris program. You can also go to the British Astronomical Web site and check out the latest libration plots on display there.

Libration plots done by B.A.A. lunar section.

Libration plots done by B.A.A. lunar section.