Surveying Earth's interior with atomic clocks

Ultraprecise portable atomic clocks are on the verge of a breakthrough. An international team lead by scientists from the University of Zurich shows that it may be possible to use the latest generation of atomic clocks to ...

Earth's gravity revealed in unprecedented detail (w/ video)

( -- After just two years in orbit, ESA's GOCE satellite has gathered enough data to map Earth's gravity with unrivalled precision. Scientists now have access to the most accurate model of the 'geoid' ever produced ...

GOCE giving new insights into Earth's gravity (w/ Video)

( -- The first global gravity model based on GOCE satellite data has been presented at ESA's Living Planet Symposium. ESA launched GOCE in March 2009 to map Earth's gravity with unprecedented accuracy and resolution.

GOCE delivering data for best gravity map ever (w/ Video)

( -- Following the launch and in-orbit testing of the most sophisticated gravity mission ever built, ESA’s GOCE satellite is now in ‘measurement mode’, mapping tiny variations in Earth’s gravity in unprecedented ...


The geoid is that equipotential surface which would coincide exactly with the mean ocean surface of the Earth, if the oceans were in equilibrium, at rest (relative to the rotating Earth[citation needed]), and extended through the continents (such as with very narrow canals). According to C.F. Gauss, who first described it, it is the "mathematical figure of the Earth", a smooth but highly irregular surface that corresponds not to the actual surface of the Earth's crust, but to a surface which can only be known through extensive gravitational measurements and calculations. Despite being an important concept for almost two hundred years in the history of geodesy and geophysics, it has only been defined to high precision in recent decades, for instance by works of Petr Vaníček and others. It is often described as the true physical figure of the Earth, in contrast to the idealized geometrical figure of a reference ellipsoid.

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