I think I understand the situation now. The definition of the moon
phases is "the times when the apparent longitudes of the Moon and Sun
differ by 0, 90, 180, and 270 degrees," according to the 1999
Astronomical Almanac (p. D4). (This seems to be becoming my favorite
book...). The maximum eclipse occurs when the moon is closest to the
anti-solar point. Now we know from my earlier messages that the Moon
is one degree north of the ecliptic at the time of the full moon, and
approaching crossing. It must be the case that some movement of the
moon toward the ecliptic more than makes up the distance increment
incurred by moving away from 180 degree apparent longitude difference.
Thus, the eclipse occurs shortly after (11 minutes) the full moon. It
makes sense to me now.
Jim
------------------- ---------------------- --------------------
| Jim Cobb | 540 Arapeen Dr. #100 | [EMAIL PROTECTED] |
| Parametric | Salt Lake City, UT | (801)-588-4632 |
| Technology Corp. | 84108-1202 | Fax (801)-588-4650 |
------------------- ---------------------- --------------------
A little learning is a dangerous thing,
Drink deep, or taste not the Pierian spring.
-- Alexander Pope. An Essay on Criticism, 1711
> > Well, that's interesting. I would have defined "full moon" as the
> > time when the moon is most nearly opposite the sun, which would be the
> > same as the time of maximum ecclipse. How else can it be defined?
> > There must be something like a projection into the ecliptic.
> >
> > Art Carlson
>
> Perhaps the difference arises from measurement with respect to the
> celestial equator in one instance and the plane of the ecliptic in the
> other. Since the moon is not precisely opposite the sun, times
> measured for "opposite" can be different for the different coordinate
> systems. I'm not sure; I will see if I can find out tonight.
>
> Jim
