While at the Dentist's office last week, I started reading the
Feb 2004 National Geographic magazine and discovered a fascinating article--
with pictures-- about a joint US/German effort to use a pair of
satellites to map the fluctuations in Earth's gravity. The project is called
GRACE (Gravity Recovery and Climate Experiment). The color-coded map they
provide is quite dramatic, with some fascinating surprises (to me, anyway) on
it:
Some areas of the ocean have "more gravity" than many mountain
ranges, while other areas of the ocean have the least gravity on the surface.
Land and water don't seem to have much correlation in gravitational terms;
certain areas of land are very low on the gravity scale and certain areas
of ocean are very high... Why?
There is no mention of whether the gravitational effects of the
moon over time (as the measurements were taken) were factored in and
subtracted out or what kind of fluctuation the moon causes in various phases
of its orbit, etc. I think the measurements are meaningless if they don't do
all of that.
Does anyone know of this project?
Judith