[Avodah] Gezeros in the BHMK

[David E Cohen]

R' Zev Sero wrote:
> The half-hour was to see the sun (or its shadow) move noticeably
> from its noon position.  The sun moves at exactly the same rate
> regardless of the day's length.  If on 21-Jun the shadow reaches
> a certain point on the BHMK wall at exactly 30 minutes past noon,
> then on 21-Dec it will also reach that point at exactly 30 minutes
> past noon, and not a moment earlier.

I agree that the sun moves exactly the same rate regardless of the day's
length.  However, based on my limited understanding (and I would appreciate
a correction from anybody who understands this better), I do not share RZS's
conclusion.

If one were to stick a pole in the ground, the shadow of the TOP of the pole
(or any other given point on it) would, indeed, move the same distance in
the 30 minutes following noon on both 21-Jun and 21-Dec.  However, the sun's
path is closer to the horizon (further south) on 21-Dec than it is on
21-Jun, so the shadow is longer.  Thus, there is less angular motion in
these 30 minutes on 21-Dec than there is on 21-Jun.

What we are really concerned with here is the projection of the shadow to
the east, since we're interested in knowing when it will move past the thick
bottom of the wall of the Beis HaMikdash.  If my understanding is correct,
this will happen SOONER on 21-Jun than it will on 21=Dec.

Hence, the most logical thing seems not only not to use "sha`os zemaniyos,"
but to use the opposite!

--D.C.