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On Apr 21, 10:18 pm, "Androcles" <Headmas...@xxxxxxxxxxxxxxxx> wrote:
> "David Weinshenker" <daz...@xxxxxxxxxxxxx> wrote in message
>
> news:480CF3B0.1D324D2E@xxxxxxxxxxxxxxxx| Androcles wrote:
>
> | >
> | > --
> | > This message is brought to you by Androcles
> | > http://www.androcles01.pwp.blueyonder.co.uk/
> | >
> | > "David Weinshenker" <daz...@xxxxxxxxxxxxx> wrote in message
> | >news:480CE8CC.47595263@xxxxxxxxxxxxxxxx
> | > | Chris L Peterson wrote:
> | > | >
> | > | > On Mon, 21 Apr 2008 10:48:09 -0700, David Weinshenker
> | > | > <daz...@xxxxxxxxxxxxx> wrote:
> | > | >
> | > | > >How would you measure the rotation: suppose you landed on this
> planet
> | > | > >from outer space, with your own time-measuring devices (that were
> | > marked
> | > | > >in some totally alien units, independent of Earthlings' "hours"),
> and
> | > | > >were wondering what the rotation period of the planet was. By what
> | > | > >observation would you take that measurement? (Observing the
> apparent
> | > | > >position of distant stars? Observing the position of sun? Using a
> | > | > >Foucault pendulum at the pole?)
> | > | >
> | > | > Which is very much the situation with us as the "aliens" when we
> measure
> | > | > the rotation period of every other body in the Solar System. We
> specify
> | > | > the period with respect to the stars (which is exactly what you
> would
> | > | > get with an inertial measurement, of course). In some cases, we
> | > | > _measure_ with respect to something else, such as an orbiting
> | > | > spacecraft. But then we convert to the inertial (sidereal) value.
> | > |
> | > | Yeah, it seems that such distinctions are lost on "oriel36", who
> | > | seems to believe that there is something inherent or absolute about
> | > | the "24 hours = 360 degrees of rotation" relationship (independent
> | > | of how that rotation is measured), appears to be unaware that the
> | > | observation of stellar transits -is- a way of "isolating axial
> | > | rotation as an independent motion to be checked". and appears
> | > | not to have spent enough time observing the night sky to note
> | > | that particular stars do in fact rise "earlier" (relative to
> | > | the solar day of terrestrial timekeeping) each night.
> | > |
> | > | -dave w
> | >
> | > Several years ago I suggested to Kellerher that he aligned
> | > two poles in his backyard with a star he'd recognise again,
> | > note the time of alignment with his wristwatch and then check
> | > again on the next few nights. Needless to say his bigotry
> | > precluded him from carrying out such a simple test.
> | > Such people are simply not worth bothering with, he'd rather
> | > rant that Flamsteed and Newton were the originators of a malicious
> | > conspiracy to which those that own clock-driven equatorial mounts
> | > even to this day are party to.
> |
> | Hmmm... bigotry, or simply the inability to
> | recognize the same star on two different nights?
> |
> | -dave w
>
> You only have to read his posts to decide that for yourself.
> Instead of actually doing it, he came back with his same old
> argument the very next day. If he won't prove or disprove
> his own contention to himself then he's a bigot. I need not point
> out that summer skies differ from winter skies to one such as
> yourself.
> If four minutes doesn't show up on successive nights, six
> months of Sirius rising and setting surely will.
> There are none so blind as those that refuse to see.
>
> --
> This message is brought to you by Androcles
> http://www.androcles01.pwp.blueyonder.co.uk/
The difference between the natural noon cycle and the 24 hour cycle as
expressed by the Equation of Time represents something quite special,a
complete astronomical explanation for why we experience variations in
daylight/darkness and the total length of the natural noon cycles.No
point expanding on this when the only responses represent a devotion
to zodiacal geometry
As for your sticks in the ground,Huygens used the same principle to
determine natural noon in order to reduce the observation to the
equable 24 hour day and from there into longitudes and the daily cycle
-
"Draw a Meridian line upon a floor (the manner of doing which is
sufficiently known; and note, that the utmost exactness herein is not
necessary:) and then hang two plummets, each by a small thred or wire,
directly over the said Meridian, at the distance of some 2. feet or
more one from the other, as the smalness of the thred will admit. When
the middle of the Sun (the Eye being placed so, as to bring both the
threds into one line) appears to be in the same line exactly you are
then immediately to set the Watch, not precisely to the hour of 12.
but by so much less, as is the Aequation of the day by the Table."
http://www.xs4all.nl/~adcs/Huygens/06/kort-E.html
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