MikeLigalig.com

By ELLIE ZOLFAGHARIFARD
PUBLISHED: 14:26 GMT, 20 August 2013 | UPDATED: 16:28 GMT, 20 August 2013


You could weigh less on different parts of the Earth because of changes in gravity.

The difference isn’t much, however. You would only weigh one per cent less if you moved from the Arctic to the Peruvian mountains, according to calculations made by New Scientist.

This is because the world is not a perfect sphere and so gravity is not the same everywhere on Earth.

For instance, gravity is weaker at the equator and at higher altitudes.

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This is an improvement on work conducted in 2011 by the GOCE satellite which created images that showed how gravity varies on different parts of the globe.

The GOCE maps revealed what the Earth would look like if it was covered in an ocean dictated by gravity.  However, the maps were only accurate to between two to 10 km.

To improve the data, Christian Hirt of Curtin University in Perth, Western Australia used existing high-resolution Earth gravity models enhanced by the gravitational signal from ultra-high-resolution satellites and topographic data.

The project was part of a major international collaboration that, for the first time, mapped the entire Earth’s gravity field in ultra-high resolution.

The map discovered unexpected locations with more extreme differences in gravitational pull.

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They found Mount Nevado Huascarán in Peru, for instance, has the lowest gravitational acceleration, at 9.7639 m/s2.

The highest is at the surface of the Arctic Ocean, at 9.8337 m/s2.

‘This suggests a variation range for gravity accelerations on Earth of about around 0.07 m/s2, or 0.7  per cent, which is about 40 per cent larger than the variation range of 0.5 per cent implied by standard models,’ said the report published in Geophysical Research Letters.

Using a super computer to calculate the data, the team at Curtin University were able to get to spatial scales of less than a 200m.

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The WGM will allow scientists to understand the structure of the Earth in far greater detail than ever before, essentially being able to see the Earth ‘from the inside’.

‘In geophysics, for example, large resource deposits can be identified more accurately, with increased gravity showing possible high-density ore bodies,’ said Professor Kuhn.

‘It will also greatly benefit the field of spatial sciences, where instrumentation needs to be very accurately oriented with respect to the Earth’s gravity.’

‘By being global and ultra-high resolution, the map enables a focus on global and regional as well as very localised and targeted areas,’ added Professor Kuhn.

The WGM project was led by the Bureau Gravimetrique International and involved significant contributions from institutions around the world, including United Nations Educational, Scientific and Cultural Organisation (UNESCO).




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