Hallo Detlef,

wenn mir auch nicht klar ist, wie die bei einer kugel west und ost bestimmen wollen

da ist nur der Terminus technicus "Western Hemisphere" schlampig übersetzt worden:

"...
Reconstructions of Earth’s magnetic field show that the axis of the dipole field was offset into the Western Hemisphere over the past approximately 10,000 years, and into the Eastern Hemisphere before that.
..."
http://www.natureasia.com/en/research/index/highlight/id/1893/

"...
The Western Hemisphere or western hemisphere is mainly used as a geographical term for the half of the Earth that lies west of the IERS Reference Meridian (which crosses Greenwich, London, United Kingdom) and east of the Antimeridian (the International Date Line), the other half being called the Eastern Hemisphere.
..."
http://en.wikipedia.org/wiki/Western_Hemisphere

Gruß
Ulrich