On Saturday 11 July 2009 21:35:10 Bill Hooper wrote: > The situation is identical to the situation of measuring the height of > mountains and other terrain RELATIVE TO sea level. Surely it can be > positive or negative depending on whether it is above or below sea > level. An absolute measure of such heights would be the distance of a > particular mountain peak or valley floor from the center of the earth. > Surely, that could not be negative.
True, but the geoid is not a sphere. The highest peak above the geoid is Chomolungma; the highest above the center of the earth is Chimborazo. Pierre
