Scott Zelenak, post: 358467, member: 327 wrote: The "Depends" crowd should like this one...
This morning the question I posed to a crew chief was;
What latitude is half the distance from the equator to the pole?I like being mean before I've had my coffee...
Considering the equatorial line passes though the center of the polar axis, my calculation is 30å¡.
If we are considering 1/2 the distance along the surface of the ellipsoid and that latitudes are farther apart as one gets away from the equator the answer is 45å¡ and a little bit.
If we are considering 1/2 the distance along the surface of the geoid the answer is indeterminate without calling out the specific geoid and the longitude.
Paul in PA
rfc, post: 358625, member: 8882 wrote: Yes, except that the generally accepted definition of "Latitude", as used in this context, defines the angular distance north or south from the equator of a point on the earth's surface, measured on the meridian of the point.
That would seem like the obvious answer, but it isn't the case. Latitude is measured normal to the ellipsoid, which is not geocentric, except at the equator and the pole. This is for the benefit of astronomic observations, as I understand it, which are oriented roughly normal to the ellipsoid (technically normal to the geoid).
[USER=7285]@Tom Adams[/USER]
"Sorry for the confusion"
No problem, I occasionally forget to take my med's in the morning too. 😉
Well, I've driven past the sign near Salem, Oregon on I-5 that says "45th parallel - halfway between the equator and the north pole". So I'm going with that!
For those that like to play with numbers I give you the following;
GRS80 Ellipsoid quadrant distance = 10 001 965. 72923 04570 92291 + meters
Clarke 1866 Ellipsoid quadrant dist. = 10 001 888. 04298 28611 88385 +meters
These numbers were calculated by elliptic integral using Mathematic V8.0
Note: the GRS80 distance in Dr. Rapp " Geometric Geodesy" part 1, 1991, page 40 has a typo error.
his value is 10 001 965. 7293 where the 2 is missing after the 9. His work was done by series expansion and all interested should
follow his work and try it. (basic geodesy)
Note #2: the Clarke 1866 ellipsoid held the major and minor axis fixed and all other numeric values were calculated from them.
Clarke 1866 ellipsoid a= 6378206.4 meters , b= 6356583.8 meters
JOHN NOLTON
