[Avodah] Announcing the Molad

[Micha Berger via Avodah]

On Sun, May 17, 2015 at 1:32pm EDT, R/Prof. Yitzchok Levine wrote on
Areivim:
: Yesterday in shul I asked a 12 year-old boy who attends a good
: yeshiva if he was willing to announce the Molad.  He looked at  me
: incredulously and said "What's the Molad?" I replied,  "You know,
: when the new moon can be seen."  He still didn't get it, and I had
: to elaborate a bit.

I want to get all nerdy with this.

The molad is actually an average, not when you could first see the
moon this particular month. From 1601 to 200 CE, the actual physical
lunation could be 6h 21m shorter or 7h 15m longer.

And, the average too changes over time. (As I've noted in the past,
it is amazing to me that we had back in the days of Galus Bavel,
a molad value that was most accurate in the same century R' Hillel II
and his Sanhedrin crated a standard calendar, some 900 years later.
Exact to within the unit of measure (the cheileq). Accurate when we
needed the value, not when we first obtained it.

Currently, the molad is around 108 chalaqim off.

And that's just the time between the molads. Then you have to ask
when in the cycle the moon could first be seen. How thin of a sliver
is visible to the typical human eye? And which longitude's clock are
you using?

And we announce the time for this point on the globe using today's hour
naming convension. If you look at (eg) the Rambam, you'd be seeing
a clock which is restarted every day at sunset, making sunset 0:00,
not a number various about 6pm. But that's only something to keep in
mind when looking at older Sepharadi sefarim, and wouldn't impact
understanding what it is we actually announce.

It would seem the molad as we now announce it would be for Kandahar,
Afghanistan. But that must be due to slippage because the molad is
too long. If we go back to the 4th or 5th cent CE, the molad is being
announced given the time around midway between the Nile and the far
(south-east) end of the Euphrates, which would have been around the
middle of Jewish settlement at the time.

In any case, calling is Jerusalem Time is a misnomer.

Anyway, because we don't know for sure what location on the globe
the molad was defined for, and how much of the current location is
due to slippage during centuries of molads growing ever longer, we
cannot definitively translate molad time to your local standard time.
We simply do not know the starting lattitude to convert from.

Bottom line, no one knows what the molad we're announcing really means.

Tir'u baTov!
-Micha

-- 
Micha Berger             Today is the 44th day, which is
micha at aishdas.org        6 weeks and 2 days in/toward the omer.
http://www.aishdas.org   Gevurah sheb'Malchus: What type of justice
Fax: (270) 514-1507                            does unity demand?