If one wanted to determine the two tripoints that are farthest apart, one should
first determine which few pairs are the most likely candidates based on their
relative antipodality from each other. This would take some trial and error.
However, since the antipodes of most continents are oceanic, there shouldn't be
an abundance of likely candidates.
Next, the few candidates might have to be evaluated for the effects of the
spheroidicity of the earth and for elevation. The earth is an oblate spheroid,
bulging at the Equator and flattened at the poles. However, the difference
between sea level diameters pole-to-pole and Equator to Equator is typically
stated in the range of 40 to 43 km. The supposedly most precise model pegs the
figure at 42,952 meters, which is less than 27 miles. On top of this distance,
elevation could add a few more miles if one found a pair of relatively antipodal
tripoints both in high mountains. Elevation would most affect diametric
distance and would be much less significant circumferentially.
Considering the relative paucity of land-land antipodes and the relative paucity
of tripoints near the poles, the variations due to spheriodicity and elevation
above sea level would probably be inconsequential in determining the two most
interdistant tripoints.
At
http://williams.best.vwh.net/gccalc.htm , you will find yet another
great-circle distance calculator into which one can enter the coordinates of any
two points and get their circumferential distance apart. This calculator
differs from the others in that you can chose from various mathematical models
of the shape of the earth, from perfectly spherical through a number of
spheroidal models. Among these last, the one currently accepted is
WGS84/NAD83/GRS80.
Lowell G. McManus
Leesville, Louisiana, USA
----- Original Message -----
From: "acroorca2002" <orc@...>
To: <BoundaryPoint@yahoogroups.com>
Sent: Wednesday, March 10, 2004 8:31 AM
Subject: [BoundaryPoint] Re: How far is it?
> really
> i dont remember that
>
> & it is an interesting question
> as well as a challenging try pointing quest
>
> perhaps even 2 of each
> since the farthest pair of points measured circumferentially
> might not be the same points as the diametrically farthest pair
>
>
> yet exactly how to solve for either set
>
>
>
> alternatively
> someone may already have solved & posted answers for them
>
> so perhaps a prior question is
> exactly how to search for any such ready made answers
>
>
> &or
> failing that
> there must be some data on the geoid already developed &
> available somewhere that might be useful toward these ends
> if we knew what to look for
>
> like
> greatest circumference & diameter figures might be a good
> place to start
> since these are likely to have been worked out to some degree
> of specificity & accuracy
>
> but where & how to find them
>
> & could we in fact approach the correct answers via these data
>
> & if so
> by exactly what means could we get there from here
>
>
>
> but can anyone solve or advance this
>
> or even clearly see the right way to go
>
>
> --- In BoundaryPoint@yahoogroups.com, "L. A. Nadybal"
> <lnadybal@c...> wrote:
> > We discussed some time back the maximum distance that any
> two places
> > on earth could be from one another.
> >
> > This site claims to deliver the distances between two selected
> points:
> >
> > www.indo.com/distance/
> >
> > LN
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>