Le centre de masse de la Terre à 1mm près

http://www.guardiannewsngr.com/science/article05

NASA scientists have created a technique to more precisely pinpoint the location of Earth's centre of mass and how it moves through space.

Knowing the location of the planet's centre of mass, determined using measurements from sites on Earth's surface, provides the reference frame through which scientists determine the relative motions of positions on Earth's surface, in its atmosphere and in space.

That information is vital to the study of global sea level change, earthquakes, volcanoes and Earth's response to the retreat of ice sheets after the latest ice age. However, the accuracy of such estimates is uncertain.

Now Donald Argus of the National Aeronautics and Space Administration's Jet Propulsion Laboratory has developed a technique that estimates Earth's centre of mass to within 1 millimetre (0.04 inches) a year by precisely positioning sites on Earth's surface using a combination of four space-based techniques.

Results of the new study are detailed in the June issue of Geophysical Journal International.