Re: shortest day

In sci.physics, Androcles
<Engineer@xxxxxxxxxxxxxxxxxx>
wrote
on Fri, 21 Dec 2007 05:35:35 GMT
<HgIaj.74622$kt3.42041@xxxxxxxxxxxxxxxxxxxxxxxxx>:

"The Ghost In The Machine" <ewill@xxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:heir35-etk.ln1@xxxxxxxxxxxxxxxxxxxxxxxxxx
: In sci.physics, Androcles
: <Engineer@xxxxxxxxxxxxxxxxxx>
: wrote
: on Thu, 20 Dec 2007 19:19:43 GMT
: <jfzaj.80777$cJ3.9527@xxxxxxxxxxxxxxxxxxxxxxxxx>:
: >
: > "Uncle Al" <UncleAl0@xxxxxxxxxxxxx> wrote in message
: > news:476ABE06.3F8D07A6@xxxxxxxxxxxxxxxx
: >: Igor wrote:
: >: >
: >: > On Dec 19, 11:48 pm, aark...@xxxxxxxxx wrote:
: >: > > Hi all,
: >: > >
: >: > > I recently read in a book that december 22 is the shortest day in
a
: >: > > year, to what extent this is true..???
: >: > >
: >: > > 1) is there any scientific basis for this claim ?
: >: >
: >: > No day is any shorter than any other. They're all 24 hours long.
: >:
: >: Daylight duration is shortest at the solstices, twice/year. One is
: >: ever amazed that Yahweh and his three religions are astoundingly
: >: incapable of assembling a decent calendar.
: >:
: >: Russia's October Revolution was in November, Israel's calendar has
: >: whole leap months, and the Muslim calendar is beneath contempt.
:
: Gregorian: adjusted solar calendar
: Russian: unadjusted solar calendar
: Israel: intercalated lunar
: Muslim: was intercalated lunar, now pure lunar
:
: >:
: >
: > Look out window.
: > See big white ball in sky.
: > When big white ball has gone, note time.
: > Keep looking out window.
: > When big white ball reappears, note time.
: > Repeat daily.
:
: And how does one note the time without a timepiece?

water clock... candle clock... In this case a sundial would
be the most appropriate.

The base resolution of a sundial is 1 solar day. Finer resolution
is possible if one knows a variant of the local annalemma and makes
appropriate corrective ticks on the dial.


I doubt Henri Wilson would agree 22 December was the shortest
day, he'd probably say it was the longest, just to be his usual
cantankerous self. Except where he lives he'd be right. I'm
sure Paul Andersen would, though, his days are shorter than
mine, and so are Eric Gisse's.

The shortest day depends on location. If one happens to be
at the point of solstice -- which for purposes of argument
is the point on the Tropic of Cancer just north of the
Tropic of Capricorn where the sun is directly overhead at
that particular moment -- one will get a different answer
as to which day is shorteast than if one is 90 degrees
east or west of that point, or at 180 degrees.




The Romans
: in particular didn't know how to make wristwatches or even
: grandfather clocks.

Really? How about that! Of course grandfather clocks don't
work too well on Roman galleys, they had to resort to ringing bells.
Out in the Old Wild West the Americans would reset the church
clock each day to the gun that fired from the nearby fort. The
sergeant-at-arms used to fire the gun at precisely midday by the
church clock, so everyone knew it was extremely accurate.

The Wild Wild West was far beyond the Romans -- you're comparing
2000 years ago with 150 years ago.


The Brits knew how to make sundials 3,500 years ago.
Here's a nice big one:
http://www.arthistory.sbc.edu/sacredplaces/images/stonehenge.jpg

That is not a sundial, though it *is* usable as a calendar.

As you can see, the time of day the photograph was taken is between
10:00 am and noon. Well... I can. Perhaps you can't. At midday
the shadows will point North.

Actually, they won't; it depends on the day. Of course they'll
be close to north, but they won't be true north.


This sketch might help.
http://web.mit.edu/mna/Public/stonehenge_416.gif


: They might have known about clepsydras, which the Egyptians
: invented circa 1400 BC, although Babylon might have had one even
: earlier.

The pyramid builders of Egypt knew how to make beer, too; those
Romans weren't too bright, were they? The Parisians and Madridians
are just like those Italians, wine drinkers the lot of them. Even the
Berliners are beer drinkers, and the Copenhageners. Skol!
I wonder if the shadow of a pyramid could be used to tell time... hmm...

But anyway, happy solstice and a merry new perihelion to you and yours
on these holy days.

On the first day of solstice my true love sent to me...
A chicken in a bare tree...

Of course what I really wanted was roast beef.


The Romans did know about cattle, as the term is derived
from the latin _caput_. No doubt they knew about roasting
the haunches thereof as well.





: >
: > Baron Victor von Frankenstein's personal assistant thinks there are no
: > nights.
: >





--
#191, ewill3@xxxxxxxxxxxxx
Windows. When it absolutely, positively, has to crash.

--
Posted via a free Usenet account from http://www.teranews.com

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