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Re: [Phys-L] field of an ellipsoidal distribution



I certainly accept that, but I doubt that the geodetic definition of the equator nor of the center of the Earth precisely comports with those understood by most people.

Meanwhile the precise definitions of "down" and "horizontal" are exactly those used without any thought at all by virtually everybody despite the fact that many claim they use different definitions.

John Mallinckrodt

On Aug 14, 2015, at 12:51 PM, John Denker <jsd@av8n.com> wrote:

If you can define "equator" and define "axis" then you
can define a center.

In fact all of those thing are known quite precisely.

More specifically, all modern geodesy is referenced to
a geoid, for which the center (and other details) are
verrrry precisely defined. The definitions are good
within fractions of a millimeter, and are consistent
with the relevant benchmarks within a meter or so.
https://en.wikipedia.org/wiki/World_Geodetic_System