[Avodah] zman hadloko erev Shabbos and motzoei Shabbos

[Zev Sero]

Michael Kopinsky wrote:
> On 1/23/07, Zev Sero <zev at sero.name> wrote:
>> Michael Kopinsky wrote:

>>> The fluctuation will depend on latitude, since I imagine that at the
>>> equator chatzos does not fluctuate, since there is no summer/winter.

>> No.  The fluctuation of noon/midnight (AKA the Equation of Time) does
>> not depend on the season but on the position of the earth in its
>> elliptical orbit, and is therefore the same everywhere.  Yes, this
>> means that days at the equator are not exactly 24 hours long.

> Do you mean 12 hours (ie that there isn't a perpetual equinox, as I had
> thought), or 24 (that the *rotation* of the earth isn't constant)?

24.  The rotation is constant enough, but noon/midnight moves, so the
length of the day (measured noon-to-noon, or midnight-to-midnight) is
usually a bit shorter or longer than 24 hours.  And is the same all over
the planet.

-- 
Zev Sero               Something has gone seriously awry with this Court's
zev at sero.name          interpretation of the Constitution.
                       	                          - Clarence Thomas