[Avodah] Molad Alert: Friday night

[Zev Sero]

On 3/03/2011 3:58 AM, Danny Schoemann wrote:
> For those who announce it in shul:
> "The was WAS on Friday night at 7 Hours and 12 parts."

That should be: "The molad was this morning, at 7 chalakim past midnight".
(Or "at 23 seconds past midnight". I don't understand why we announce it
in minutes and chalakim, a division that has no traditional basis; either
use just chalakim, for tradition's sake, or minutes and seconds. It's not
as if there's anything holy about the chelek, it's just an archaic time
unit used at the time when the rules for the perpetual calendar were set,
and the average month was therefore rounded to the nearest one.)

NOTE: The actual molad, as opposed to the calculated one, will be on
Friday night at 10:46 Israeli standard time, i.e. 11:06 Yerushalayim Mean
Time, which makes the calculated molad only 54 minutes off. Not bad
considering that we know our month has a rounding error of 1/3 of a
second, accumulating to 4 seconds a year, or one hour every 900 years.

SECOND NOTE: For those who like to calculate the molad themselves,
working from a known benchmark, this month will be a new one that can be
easily remembered. The last easily-remembered benchmark was Marcheshvan
5665, 79 months ago, which was getting to be a bit much to calculate in
ones head. The easiest method, I find, is to work out how many months
it has been since the benchmark, multiply that by 1.5 days and mod 7,
then multiply the number of months by 3/4 of an hour and add that to
the result, then subtract that number of minutes and add that number of
chalakim, then add the benchmark.

E.g. 79 is 80 minus 1. 80 times 1.5 days is 120 days, mod 7 is 1 day.
Minus 1.5 days is minus half a day. 3/4 of 80 hours is 60, minus 3/4 of
an hour is 59:15; minus 79 minutes, or 1 hour 19, brings us to 57:56.
Plus 79 chalakim, or 4 minutes 7, gets us back to 58:00:07. 48 hours
is obviously 2 days, so we're at 2 days, 10 hours, and 7 chalakim.
Add the known benchmark of Thursday at 2 am, gets us Shabbos at noon
and 7, minus the half day we got earlier gets us to midnight and 7.
And now we can scrap that old benchmark and start counting from this one,
so the arithmetic will get easier. Particularly in working out how many
months it's been, which involves working out how many leap years there
have been, and remembering which year it was in.


On 3/03/2011 10:48 AM, Micha Berger wrote:
> On Thu, Mar 03, 2011 at 01:38:11PM +0200, Akiva Blum wrote:
>: Please note, that should be 12 hours (midnight) and 7 chalakim.

> Wondering... Does anyone's shul's gabbai also announce the time in the
> local standard? And, the Avodah question: How is it appropriate /not/
> to?

> As I understand it, the original idea was for people to know the time
> of the molad.

The only real reason to know the molad is to calculate from it when
rosh chodesh should be.  And since kiddush hachodesh can only take
place in EY, all that matters is when the molad is then.  Of course
with our system all that matters is the molad of Tishri, which
ironically is the only one not announced, so we have to calculate it
from the one that is announced!  But we can use our molad for a rough
approximation, and see that this coming rosh chodesh *ought* to be on
Shabbos.  So we wonder why it's Monday instead, and are led to the
answer, that this coming molad Tishri will be late Tuesday afternoon,
making Rosh Hashana Wednesday, and that would mean Yom Kippur on Friday
which we don't like, so we'll push it to Thursday, and that drags all
the roshei chodesh of this year forward a day or two.

-- 
Zev Sero
zev at sero.name