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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
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