[Avodah] Molad Alert: Friday night

[Micha Berger]

On Thu, Mar 10, 2011 at 06:06:20AM +0000, kennethgmiller at juno.com wrote:
: Reb Micha: You write that the location where the molad is correct
: has been slipping eastward. Could you please calculate backwards from
: nowadays, and backwards from the days of the Sanhedrin? ...

Others already did, and I already posted their results. Today the
molad is accurate in Qandohar, and in the final days of the Sanhedrin,
it was accurate at around midway from Nile to the far end of the
Euphrates. That's the whole thing you questioned earlier in the same post.

Useful for visualizing how the length of the molad (as opposed to the
zero-point) matches reality is Dr Irb Bromberg's chart compating actual
lunation (2nd order approximation) and molad
<http://individual.utoronto.ca/kalendis/hebrew/Molad_All_Months.pdf>. The
black dots are data points, the blue curve being the "quadratic
least-squares statistical regression line". IOW, the "mean" that minimizes
the total distance to those dots. Presumably what the molad represents.

The blue line gets closes to 0 in 4119 (see the base text at
<http://individual.utoronto.ca/kalendis/hebrew/molad.htm>). Again,
during Rabbi Hillel II's nesi'us. And NOT back when we got it, which
was before galus Bavel. Since it was first documented in Bavel by
Babylonians during that period, a millenium before. That's the chizuq
emunah data point I've mentioned in the past.

Back to our discussion of where the molad was computed for... The minimum
error is +23 min, not zero. IOW, the molad is right in length (to the
nearest cheileq) in R' Hillel's day, but wrong in starting point. If
we look up where that's accurate, we are going about 5deg 45' east
(translating 23 min of time to longitude) of Y-m. Somewhere in Eastern
Jordan and the aforementioned midpoint between something like Alexandria
to Nehardaa -- the large Jewish populations at the extremes.

:                                                         Is it possible
: that even if the molad is not accurate for Yerushalayim *today*, it was
: indeed accurate for Yerushalayim at *Creation*?

Or maybe when HQBH said "hachodesh hazeh lakhem".

Well, let's figure that out... Leaving out 2nd order effects just to
get a thumbnail...

Today the molad is accurate for 65deg 43' E, and 1550 years ago, it was
accurate at 40deg 58' E (more on that, below). Plotting backwards linearly
(leaving out 2nd order effects just to get a thumbnail) that's a drift of
1485' or a drift of 95.8' per cent. Which brings us back to Y-m about 370
years before Hillel II, or a century after churban bayis or so. Maybe if
we threw in those second order effects, we would get the year 4000 (for
CI fans) or the year of churban bayis or something significant like that.

But then we would have to explain why we use a molad length that was
most accurate in a different year than the molad starting point was
most accurate.

-Micha

-- 
Micha Berger             "'When Adar enters, we increase our joy'
micha at aishdas.org         'Joy is nothing but Torah.'
http://www.aishdas.org    'And whoever does more, he is praiseworthy.'"
Fax: (270) 514-1507                     - Rav Dovid Lifshitz zt"l