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Re: Simple Calculation of Sunset Time required

Subject: Re: Simple Calculation of Sunset Time required
From: David Weinshenker <daze39@xxxxxxxxxxxxx>
Date: Mon, 21 Apr 2008 13:06:08 -0700
Newsgroups: sci.astro, sci.astro.amateur, comp.home.automation

Androcles wrote:
> 
> --
> This message is brought to you by Androcles
>   http://www.androcles01.pwp.blueyonder.co.uk/
> 
> "David Weinshenker" <daze39@xxxxxxxxxxxxx> wrote in message
> news:480CE8CC.47595263@xxxxxxxxxxxxxxxx
> | Chris L Peterson wrote:
> | >
> | > On Mon, 21 Apr 2008 10:48:09 -0700, David Weinshenker
> | > <daze39@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

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