Goce satellite views Earth’s gravity in high definition
It is one of the most exquisite views we have ever had of the Earth.
This colourful new map traces the subtle but all pervasive influence the pull of gravity has across the globe.
Known as a geoid, it essentially defines where the level surface is on our planet; it tells us which way is “up” and which way is “down”.
It is drawn from delicate measurements made by Europe’s Goce satellite, which flies so low it comes perilously close to falling out of the sky.
Scientists say the data gathered by the spacecraft will have numerous applications.
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Launched in 2009, the sleek satellite flies pole to pole at an altitude of just 254.9km – the lowest orbit of any research satellite in operation today.
The spacecraft carries three pairs of precision-built platinum blocks inside its gradiometer instrument that sense accelerations which are as small as 1 part in 10,000,000,000,000 of the gravity experienced on Earth.
The ‘standard’ acceleration due to gravity at the Earth’s surface is 9.8m per second squared.
In reality the figure varies from 9.78 (minimum) at the equator to 9.83 (maximum) at the poles.
This has allowed it to map the almost imperceptible differences in the pull exerted by the mass of the planet from one place to the next – from the great mountain ranges to the deepest ocean trenches.
Two months of observations have now been fashioned into what scientists call the geoid.
Goce satellite views Earth’s gravity in high definition [BBC News]