... New way to the center of Earth . A NASA technique pinpoints Earth's exact center of mass to understand global climate change. ... A new NASA-developed technique estimates Earth's center of mass to within 1 millimeter (.04 inches) a year by using a combination of four space-based techniques. ... Scientists currently define Earth's center in two ways: as the mass center of solid Earth, or as the mass center of Earth's entire system, which combines solid Earth, ice sheets, oceans, and atmosphere. ...