[Avodah] Announcing the Molad

Micha Berger via Avodah avodah at lists.aishdas.org
Mon May 18 11:47:01 PDT 2015


On Mon, May 18, 2015 at 01:03:32PM -0400, Zev Sero via Avodah wrote:
: On 05/18/2015 12:41 PM, Micha Berger wrote:
: >What am I missing?
: 
: That what we announce is *not* anything to do with the actual moon, which
: the eidim in RG's time would have claimed to have seen, but the notional
: averaged moon on which *our* calendar is based...

First, as Zev noted to me in private, I meant RH 25a (not Mes' Shabbos).

But the point I asked "what am I missing?" about was Rabbi Gamliel
questioning what people thought they saw, not the average. In R'
Gamliel's day, the length of the molad was pretty close to exact; even
today it's closer than they had any way to measure. But that's still an
average. And real values can be more than 6 hr earlier. So, how can R'
Gamliel question someone's observation for being less than a molad, when
in half of all months re'iyah will be early -- and many 5 or 6 hr early.

: So we do know exactly what we are announcing: the number on which the
: calendar is based.  Given this Shabbos's announcement, one can easily
: calculate that next Rosh Hashana will be on a Monday, exactly as it
: should be.

As I said in my previous post... Yes, that explans the length of the
molad, but not the point in the idealized cycle. How much moon must be
visible for it to be a new moon? Or more accurately, what was visible
when the molad was al pi re'iyah that we are now using a simplified
model to approximate? And we can't just calculate what it is the molad
is approximating, because we don't know what clock to use.

It looks to me like Hillel was using a point halfway between EY and
Bavel, somewhere in the center of the contiguous Jewish settlement. But
that's largely guesswork.

On Mon, May 18, 2015 at 01:49:49PM -0400, Prof. Levine via Avodah wrote:
: My understanding is that what is announced is Jerusalem solar time
: and this is different from Jerusalem local time.

Which is why I left out the word standard, writing "Jerusalem Time"
rather than Israel Standard Time.

But as I wrote above, it's not. See also my first post (for Avodah) on
this thread for more detail.

In 1999, R Yisrael Medad posted something about this on MJ, after
having R/Prof Ely Merbach, R/Prof Yaakov Loewinger and the Bar Ilan
astronomy dept bad the question around. See
<http://www.ottmall.com/mj_ht_arch/v29/mj_v29i58.html#CPG>

They assume Jerusalem Mean Time, but they make the fundamental error of
discussing mean conjunction -- no moon -- not the first sliver.

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?



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