[Avodah] Calendar Drift (was: Zayin adar)

[David E Cohen]

R' Micha Berger wrote:
> When the calendar was made, Adar II would always be the last month
> before the vernal equinox, and thus always be mazal Dagim.

When the calendar was made, yes, but probably not before the calendar was
made (when the Sanhedrin was declaring shanim me`ubaros) -- at least
certainly not when the Mikdash was still in existence.  R' Zev Sero
demonstrated this nicely in the bottom paragraph of this post:
http://www.aishdas.org/avodah/vol17/v17n022.shtml#18

As an aside, in the centuries between the Churban and the institution of the
fixed calendar, all of the other reasons besides tekufah were no longer
relevant.  I wonder if at that point, the Sanhedrin decided to make Pesach
always fall on the first 15th following the equinox, or if they continued to
be me`abeir shanim based on the other factors as well, in the belief that
"meheirah yibaneh hamikdash."  I'd be interested in seeing evidence one way
or the other.

RMB:
> Today, there are years (like this one) in which Adar II is in Teleh,
> and Adar I would be Dagim.

About a week ago, before Purim Katan, I heard somebody remark that since the
Sanhedrin used to avoid making a shemitah year a shanah me`uberes (that can
be added as a second factor that would have been relevant even post-Churban,
BTW), we should be prepared for the possibility that Mashiach would come in
the following few days and declare that it is not a shanah me`uberes after
all, and we should be ready to celebrate Purim.  It occurred to me that this
possibility exists only thanks to the calendar drift.  Otherwise, if 14 Adar
II would have been scheduled to come out before the equinox (rather than the
day after the equinox, as it will be this year), then there would be no
choice but to keep this as a shanah me`uberes.

--D.C.