Above picture shows a potato-shaped earth. It’s called a geoid and shows the actual (but highly exaggerated) form of our planet. The surface of potato earth represents the form of an ideal surface which water would adopt if it covered the whole earth and if there would be no currents induced by tides or wind. Such a surface would always and everywhere be perpendicular to the vector of the gravitational force. The ideal surface serves scientists as a reference surface for analysing circulation, sea-level change and ice dnyamics in oceans, all of which are affected by climate change.
The above visualization has been assembled from data gathered by GOCE (Gravity field and steady-state Ocean Circulation Explorer), a satellite whose mission is part of ESA‘s Living Planet Programme. GOCE has been launched in March 2009 and has been gathering data for about a year with its six accelerometers. GOCE is scheduled to continue data collection until the end of 2012.
A highlight of this satellite mission is the low orbit of about 250km. This is so low that the satellite requires propulsion in order to maintain the orbit and not dive through the atmosphere and crash to the ground (see image above). More details can be found on the mission website.
A more detailled report on GOCE’s highly detailled gravity dataset can be found on the website of the European Space Agency (ESA). BBC has a story on GOCE and a rotatable visualization of its gravity measurements.