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>
> I don't know about poles 'shifting all over the place' but perhaps the
> latitude of a bench mark can change over the eons.
>
> We know the first order approximation for the earth's shape is an
> ellipsoid; the earth equatorial circumference being somewhat larger
> than the polar circumference. That causes the distance of a degree of
> latitude to be dependent upon the latitude in contrast to the
> generally accepted value of a nautical mile per degree for a spherical
> earth.
>
> What determines the relative length of these dimensions? The forces
> generated by the earth rotational angular velocity.
> So, does it follow that a bench mark, not located on the equator or on
> a pole, will move as an 'elastic' earth changes shape due to a change
> in the rotational velocity?
> I don't know about poles 'shifting all over the place' but perhaps the
> latitude of a bench mark can change over the eons.
>
> We know the first order approximation for the earth's shape is an
> ellipsoid; the earth equatorial circumference being somewhat larger
> than the polar circumference. That causes the distance of a degree of
> latitude to be dependent upon the latitude in contrast to the
> generally accepted value of a nautical mile per degree for a spherical
> earth.
>
> What determines the relative length of these dimensions? The forces
> generated by the earth rotational angular velocity.
> So, does it follow that a bench mark, not located on the equator or on
> a pole, will move as an 'elastic' earth changes shape due to a change
> in the rotational velocity?
It will, but the effect is negligeable, quantitatively,
Jan
HIPAR wrote:
> . . .
> . . . That causes the distance of a degree of
> latitude to be dependent upon the latitude in contrast to the
> generally accepted value of a nautical mile per degree for a spherical
> earth.
>
> . . .
> . . . That causes the distance of a degree of
> latitude to be dependent upon the latitude in contrast to the
> generally accepted value of a nautical mile per degree for a spherical
> earth.
>
> . . .
I'm sure you meant a nautical mile per minute.
Roy Lewallen
> That causes the distance of a degree of
> latitude to be dependent upon the latitude in contrast to the
> generally accepted value of a nautical mile per degree for a spherical
> earth.
> latitude to be dependent upon the latitude in contrast to the
> generally accepted value of a nautical mile per degree for a spherical
> earth.
A nautical mile is 1852 meter (exactly)
and nothing else,
Jan
On May 5, 8:01=A0am, nos...@de-ster.demon.nl (J. J. Lodder) wrote:
> > That causes the distance of a degree of
> > latitude to be dependent upon the latitude in contrast to the
> > generally accepted value of a nautical mile per degree for a spherical
> > earth.
> > latitude to be dependent upon the latitude in contrast to the
> > generally accepted value of a nautical mile per degree for a spherical
> > earth.
> A nautical mile is 1852 meter (exactly)
> and nothing else,
> Jan
> and nothing else,
> Jan
I have no problem with that definition and don't find it inconsistent
with the historical one nautical mile per minute (thanks Roy)
spherical earth definition. This is from Ed Williams Aviation Page
(very famous):
'Note: the nautical mile is currently defined to be 1852 meters -
which to be consistent with its historical definition implies the
earth's radius to be 1.852 * (180*60/pi) =3D 6366.71 km, which indeed
lies between the currently accepted ( WGS84) equatorial and polar
radii of 6378.137 and 6356.752 km, respectively. Other choices of the
earth's radius in this range are consistent with the spherical
approximation and may for some specialized purposes be preferred'.
I suspect the earth radius would indeed settle into cited range if we
stopped it from turning and allowed it time to lose its 'mid-rib
bulge'.
--- CHAS
wrote:
>On May 5, 8:01 am, nos...@de-ster.demon.nl (J. J. Lodder) wrote:
>> > That causes the distance of a degree of
>> > latitude to be dependent upon the latitude in contrast to the
>> > generally accepted value of a nautical mile per degree for a spherical
>> > earth.
>> > latitude to be dependent upon the latitude in contrast to the
>> > generally accepted value of a nautical mile per degree for a spherical
>> > earth.
>> A nautical mile is 1852 meter (exactly)
>> and nothing else,
>> Jan
>> and nothing else,
>> Jan
>I have no problem with that definition and don't find it inconsistent
>with the historical one nautical mile per minute (thanks Roy)
>spherical earth definition. This is from Ed Williams Aviation Page
>(very famous):
>'Note: the nautical mile is currently defined to be 1852 meters -
>which to be consistent with its historical definition implies the
>earth's radius to be 1.852 * (180*60/pi) = 6366.71 km, which indeed
>lies between the currently accepted ( WGS84) equatorial and polar
>radii of 6378.137 and 6356.752 km, respectively. Other choices of the
>earth's radius in this range are consistent with the spherical
>approximation and may for some specialized purposes be preferred'.
>I suspect the earth radius would indeed settle into cited range if we
>stopped it from turning and allowed it time to lose its 'mid-rib
>bulge'.
>--- CHAS
>with the historical one nautical mile per minute (thanks Roy)
>spherical earth definition. This is from Ed Williams Aviation Page
>(very famous):
>'Note: the nautical mile is currently defined to be 1852 meters -
>which to be consistent with its historical definition implies the
>earth's radius to be 1.852 * (180*60/pi) = 6366.71 km, which indeed
>lies between the currently accepted ( WGS84) equatorial and polar
>radii of 6378.137 and 6356.752 km, respectively. Other choices of the
>earth's radius in this range are consistent with the spherical
>approximation and may for some specialized purposes be preferred'.
>I suspect the earth radius would indeed settle into cited range if we
>stopped it from turning and allowed it time to lose its 'mid-rib
>bulge'.
>--- CHAS
And then, when the earth stopped turning (it won't, btw, there is too
much momentum to overcome)...the part exposed to the sun 24/7 will
turn to desert, and the part hidden from the sun will become a frozen
wasteland. ALL because of your calculator and your book.
I suggest for the sake of humanity and all the other species that call
themselves Earthlings, that you destroy your Weapons of Mass
Destruction forthwith and return to paper, pencil, and maybe an
abacus.
Nick
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> > misunderstood what he meant. Just curious. Thanks.