A matter of gravity

Map of planetary field is sharpest ever

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GRAVITATIONAL PORTRAIT Yellow and red represent some of the sharp deviations from the average pull of Earth’s gravitational field, gathered in this new map by the European GOCE satellite. ESA/HPF/DLR

As seen by a supersensitive gravity-detecting satellite, Earth isn’t a pale blue dot. It’s a colorful, irregular lump. Kind of like a tuber.

“Rotating potato — I don’t like this word,” said Roland Pail, a geoscientist at the Technical University of Munich. He and other researchers unveiled the new map of the Earth’s gravity field on March 31 at a scientific workshop in Munich.

Yet a rainbow potato it is. This image represents a sort of theoretical sea level known as the “geoid” — a surface where the ocean would rest if not pushed around by internal currents, tides and the weather.

Gravity varies from place to place because of many factors, such as the presence of mountain ranges, the bulge around Earth’s equator, and the moon’s gravitational influence. The new snapshot comes from the European Space Agency’s GOCE satellite, launched in 2009 to map the geoid. GOCE dances along at the top of the atmosphere, using six special accelerometers to measure, many times a second, how the Earth’s gravity tugs on the spacecraft.

A highly accurate gravity map will allow researchers to fine-tune their understanding of ocean currents, sea level height, ice caps and other changing parts of the planet.

PLANETARY PULL from Science News on Vimeo.

Rotating potato or insight into the planet’s deepest secrets? This new map of the Earth’s gravity field, gathered by the European GOCE satellite, shows how, in regions such as Iceland and Indonesia, the planet’s internal structure creates large gravitational deviations (yellow and red) from the average.

Alexandra Witze is a contributing correspondent for Science News. Based in Boulder, Colo., Witze specializes in earth, planetary and astronomical sciences.

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