VMs: Re: Moons in Zodiac?

[Greg Stachowski <greg@xxxxxxxxxxxxxxxxxxxxxx>]

Hello Glen,

A couple of points, before I dig out Ye Olde Astronomicale Programme :)

On Wed, 11 Sep 2002, GC wrote:

> 4.  that the two colors of moon-faces denote waxing and waning
> moons.

If the colours denote waxing and waning, why is the crescent always on the
same side? The moon always waxes and wanes on opposite sides (waxing - lit
crescent on the right, horns facing left, dark side on left; waning - lit
crescent on left, dark side on right, as viewed from the northern
hemisphere).

> 5.  that the moon-faces denote the moon's state on the first of
> each month (no full moons present this year).

The convex (as opposed to crescent) appearance of the moon lasts for about
two weeks each cycle (one week waxing, one waning). The drawings seem
rather too innaccurate to place the phase of the moon to better than
perhaps 3-4 days in each of those weeks, although I shall have a more
careful look when I do the calculations.

Given that the length of the lunar month is 28 days, in a given year the
moon is broadly (to within a few days) in the same phase on the first day
of any two consecutive months, it would not alternate waxing/waning in
such an obvious manner.

What this might be though (and I wouldn't have thought of it if it wasn't
for your suggestion) is something like the following - that the moons
indicate when the moon rises or is visible, with the light circles
indicating moonrise (say) in the morning and the dark ones in the evening.

I shall check out these possibilities probably next week when I have a
little free time.

> Taking a lot for granted, what years between 1400 and 1550 would
> find the moon in the depicted state of change?  Curious?

Regards,

Greg
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