Re: VMs: How did Ptolemy know about time zones

[Pamela Richards <spirlhelix@xxxxxxxxx>]

Hi, Jorge

I know I can't answer the portion of your question
that is directed to Rene.

As for your questions about Ptolemy, he knew about
"transits". . . that is, I think you mean aspects
between planets.  Ptolemy "invented" the conventional
aspects:  trine, sextile, quadrile (square),
opposition.

Time zones, of course, are a modern innovation and the
different times of events in different locations would
be obscured to a degree by the fact that everyone was
using "tropical time", or "solar time", if you will,
measured by the Sun or stars.   

I'm just doing a thought experiment, but this is what
I envision thus far.  Eclipses might work as a measure
of the same event being visible at different sectors
of the sky, indicating an earlier or later time, like
this:

Say, a lunar eclipse is taking place at night.  One
person in an Eastern location sees the eclipse occur
on the Western horizon.  Another person, to the West
of him, sees the same eclipse take place higher above
the horizon.  A third person, the person in a location
most Westerly, sees the eclipse happen still higher in
the heavens.  If they can describe where they see the
eclipse in the sky, calculations can be taken to show
the time of the eclipse in different locations, and
the differences can be noted.

Just a stab at it.

Warmly,

Pam 


--- Jorge Stolfi <stolfi@xxxxxxxxxxxxx> wrote:

> 
> Rene,
> 
> I am not sure I undestand your current view of the
> Zodiac pages. Do
> you feel that the events presumably encoded by the
> stars and nymphs
> are all of the same type (e.g. all of them are star
> risings, all of
> them are meridian crossings, etc.)? If so, perhaps
> we can match the
> *sequence* of magnitudes inferred from the VMS with
> the sequence of
> magnitudes of real stars sorted by longitude.
> 
> Or do you feel that some events are risings, some
> are settings, etc.?
> 
>   > [Elmar:] And this is exactly my question: How
> did he measure time
>   > with the necessary accuracy? Or, which amounts
> to the same, how
>   > did he synchronize events which were seperated
> by a considerable
>   > distance? A rough estimate would assume a
> difference of some 15km
>   > as the equivalent of 1', the smallest increment
> he would be able
>   > to measure.
> 
> I don't know how he did it, but he *could* have
> confronted reports of
> any event that was visible at two distant locations
> and whose timing
> was sufficiently well-defined. A lunar eclipse
> should be adequate, I
> think.  Or the Moon eclipsing a star.
> 
> Planetary conjunctions may be adequate, too, if
> measured with 
> sufficiently precise instruments. Would it be
> possible at 
> that time?
> 
> Was Ptolemy aware of planetary transits?
> 
> Solar eclipses obviously wouldn't work, because they
> are not
> simultaneous; but perhaps they were thought to be...
> 
> All the best, 
> 
> --stolfi
>
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=====
"I'd rather learn from one bird how to sing, than to teach ten thousand stars how not to dance."

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