Friday, July 2, 2010

Sri Lanka, Have You Lost Weight?

Apparently. A study has come out showing that gravity is not quite as uniform on this planet as you might think.

This is the finding of GOGE, the Gravity Field and Steady-State Ocean Circulation Explorer, a satellite launched last year to detect minute variations in gravity across Earth's crust and oceans.

What you're looking at is the geoid: likened to a level used in construction work, this is a level that covers the planet.

First, imagine an 'elipsoid'- a perfectly smooth surface covering the entirety of the planet, or at least its generalized shape. The geoid is not smooth; rather, the map shows the elevation in relation to the elipsoid that the geoid would have to be in order to ensure an equal gravitational pull at all points along the planet, a pull such that if you placed a ball along one of the geoid's slopes, it would not roll.

So if you're in Sri Lanka, the gravitational pull is weak enough that the geoid has to be about 100 meters under the elipsoid, and in Papua New Guinea, the pull is strong enough that the geoid must be about 80 meters above the elipsoid, in order for the two places to have equal gravitational pull.

Why is this important? If all the icecaps melted and all the meltwater went into the global ocean, and there wasn't any wind or currents or tides, this is the shape the water would take.

For more, click the link, because it's 2 AM here.

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