مرکز جرم زمین کمتر از آن چیزی که فکر می کردیم جابجا می شود

Earth's center of mass drifts less than we thought

Where is Earth's center of mass? The answer seems trivially obvious. It's right in the middle of the planet. Ah, but that kind of thinking won't get you a paper in the Geophysical Journal International. It's also not a trivial question. Knowing Earth's center of mass to within millimeters reveals some interesting facts about our planet.