Re: Earth rotation

From: Oriel36 (geraldkelleher_at_hotmail.com)
Date: 06/23/04 

Date: 23 Jun 2004 09:54:43 -0700

bobg@radix.net (Robert Grumbine) wrote in message news:<10de770e6fbc8ec@corp.supernews.com>...
> The 'mean sun' is indeed a fiction. That was known, and the fact
> duly used, since its inception. But it is a useful thing to declare a
> day to be 24 hours, as measured by stable chronometers, rather than
> to rely on solar observations of meridian crossings and then be recomputing
> the length of the second every day, or changing how many seconds there
> are in the day, every day.
>
> We also have, in science, the equally fictitious idea of
> 'standard temperature and pressure'. It's useful to define,
> but outside of certain contrived situations, never actually
> occurs. Does that bother you too?
>

You standard for axial rotation through 360 degrees is 23 hours 56 min
04 sec while the actual figure is 24 hours exactly.If you cannot
determine the fundamental rotation rate of the Earth on its axis I
suggest you take up stamp collecting or gardening.

http://rubens.anu.edu.au/student.projects97/naval/defin.htm

Unfortunately not many websites include the Equation of Time
correction at noon in tandem with the 24 hour/360 degree equivalency
to demonstrate that constant axial rotation already existed before
Flamsteed trumped up a false premise of constant axial rotation linked
directly to stellar circumpolar motion.

 
> >> The Maya had determined the length of the year -- time for the
> >> sun to return to the same place in the sky relative to the fixed
> >> stars -- to be 365.242 (and a bit, but I forget that bit and it
> >> doesn't affect the argument) days. Given the declaration that a
> >> day (specifically solar day) is 24 hours, the year is, then,
> >> 8765.808 hours.
> >>
> >
> >To determine the annual orbit as 365 days 5 hours 49 minutes you have
> >to determine the equable 24 hour day FIRST.The only means to do that
> >is assume that axial rotation is constant wrt the Sun and apply the
> >Equation of Time to equalise the natural variation from one rotation
> >to the next.
>
> Actually, no, you don't. First, and probably major for your
> misunderstandings, is that the Maya (and others) did not determine
> the year as being 365 days, 5 hours, 49 minutes. To make that
> determination, one needs a chronometer that measures hours and minutes
> (and which uses 24 hours in a day, which the Maya did not, and 49 minutes
> in an hour, which is unlikely -- minutes per hour is legacy of sexigisimal
> arithmetic, for which Babylon was the only source. The Maya used 10
> or 20 for math.)
>

Simple logic,to determine the annual cycle as 365 days 5 hours 49 min
it is required to determine the equable 24 hour day FIRST.The only
means to determine the equable 24 hour day is via constant axial
rotation and the Equation of Time correction at noon.

> What they actually determined was the length of year being
> 365.242+ days. Closer to how they'd have done it, they determined
> the year to be 365 + 1/4 - 1/128 days. One route to the determination
> is to measure the elevation from the horizon of bright stars at sun
> rise and sun set. They move approximately 1 degree per day. Repeat
> for 366 days, and you'll find that on the 365th day, the star was
> 1/4th degree shy of getting back to where it was when you started,
> but on day 366, it is 3/4th of a degree past the point. Repeat over
> 32 years (Mayan records, as do many others, extend for more than
> a century), and you've got another 1/4th degree discrepancy.
>
> At no time does anybody need a chronometer, nor high precision
> measuring equipment. 1/4th degree is half the width of a full
> moon, i.e., very large optically.
>
> To the extent the sun is involved in the measurements, it is
> the actual, observed, sun. So you're happy, right?
>

How can anyone be happy with geocentricity,I suggest you go outside
tommorrow morning and enjoy the Earth's axial rotation out of its
orbital shadow and even consider its orbital direction which falls
close to or on the daylight/darkness line at dawn.

http://www.users.muohio.edu/primacag/images/earth%20from%20space.gif

http://www.mhhe.com/physsci/astronomy/fix/student/images/04f15.jpg

 
> >> Note, too, that all the preceding is equally true if you prefer
> >> to consider the rest of the universe to be moving around the earth.
> >
> >Perhaps geologists and the rest of humanity wish to have their
> >intelligence insulted but that all this is done on the most remarkably
> >simple and erroneous premise that the Earth's rotation can be linked
> >directly to the structure of the remainder of the cosmos and actually
> >taken as valid.
> >
> >Allow me show you the structure of your universe derived from stellar
> >circumpolar motion -
> >
> >http://ottawa.rasc.ca/pictures/pdelorme/polaris.jpg
> >
> >In the 20th century they even jettisoned this structure and decided
> >that 'every point is the valid center' of the universe.
>
> The picture you reference is a pretty one, and a common one.
> Has nothing to do with the structure of the universe, but does
> illustrate the apparent motion of the stars, and is entirely
> in keeping with the earth rotating.
>
> But what's your objection to 'every point is the valid center' of the
> universe? I'd describe it as '_a_ valid center', but that's details.
> You're ticked off somehow about geocentrism, which is fine. But
> if it's not to be geocentric, and it's not to be relativistic, then
> what _is_ your preferred center to the universe? And how did you
> decide that?

The geologists may wish to consider the Earth's axial and orbital
motion and its effects on crustal movement notwithstanding that the
Earth has another known rotation around the Milky Way axis.I have
already indicated to the geologists why physicists and astronomers are
currently thoroughly impractical in dealing with rotations as they
can't even get the fundamental rotation rate of the Earth right.

 Not one geologist objected to your statement that -
   "Note, too, that all the preceding is equally true if you prefer to
consider the rest of the universe to be moving around the earth."

I wonder how many geologists can figure out where that truly
ridiculous statement comes from,I can simply show the sidereal image
and tell them to swap the position of the Sun and the Earth,an image
where the Earth has a constant orbital motion which is in direct
conflict with Kepler's second law and a constant axial rotation wrt
the Sun every 24 hours (It does'nt as this is why the Equation of Time
correction is necessary).

http://astrosun2.astro.cornell.edu/academics/courses//astro201/sidereal.htm

Relevant Pages

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    ... you will stop right there as you are using the term 'mean sun' ... >is assume that axial rotation is constant wrt the Sun and apply the ... is to measure the elevation from the horizon of bright stars at sun ... >and uses the 24 hour clock to calculate the motion of a star back to ...
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  • Re: Earth rotation
    ... you will stop right there as you are using the term 'mean sun' ... >is assume that axial rotation is constant wrt the Sun and apply the ... is to measure the elevation from the horizon of bright stars at sun ... >and uses the 24 hour clock to calculate the motion of a star back to ...
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  • Re: Earth rotation
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