America is dense and Europeans lack gravity

March 31, 2011 8:44 PM

The GOCE satellite has completed its survey of the Earth's gravitational field. This visualisation of different gravitational potentials (the geoid) will help us understand earthquakes and the flow of ocean currents by comparing the actual height of the surface with the one predicted by the geoid.

The satellite's orbit is so low (about 255 km, or 160 miles) that it must fire xenon ion thrusters to counteract atmospheric drag (cool pic). Ion thrusters! I tell you, we're living in the future.

posted by Joe in Australia (11 comments total)

Are the distortions in the 'geoid' image amplified, or does gravity really vary that much? If so, why is the Earth actually so round if gravity is so distorted? Is it really just the tides and currents that keep the oceans in a nice well behaved sphere?
posted by jpdoane at 8:59 PM on March 31, 2011

From the Fine Article :

The differences have been magnified nearly 10,000 times to show up as they do in the new model.

That said,

Even so, a boat off the coast of Europe (bright yellow) can sit 180m "higher" than a boat in the middle of the Indian Ocean (deep blue) and still be on the same level plane.

This is because although the earth is, to a certain degree, spherical, the density is not uniform. This leads to sea level being at different actual heights in different places.
posted by Pogo_Fuzzybutt at 9:15 PM on March 31, 2011

Higher gravity and sunshine - this explains why Southeast Asians are supermen!

Seriously though, the picture is awesome in the most literal sense of the word for me.
posted by ooga_booga at 9:41 PM on March 31, 2011

Between the Lumpy Earth and the Ion Drive, this post is full of SCIENCE WIN!
Thanks Joe!
posted by djrock3k at 9:55 PM on March 31, 2011

This is fantastic on every level.
posted by tumid dahlia at 10:21 PM on March 31, 2011

Does this mean WGS84 is about to become irrelevant?
posted by one_bean at 10:59 PM on March 31, 2011

While this is a pretty and all I'll name the plastic dinosaur on my desk after the person who discovers a gradient map showing the variance from the mean in Newtons, corrected for variation from the idealized geoid. It's worth noting this looks to correspond rather closely with the difference of the Earth from an idealized geoid.

Still cool.
posted by EsotericAlgorithm at 3:26 AM on April 1, 2011 [1 favorite]

The Goce satellite is the only one to my knowledge that needs to be somewhat aerodynamic in order not to be disturbed in its course by the very fine atmosphere at that altitude. It is 90% satellite but 10% plane. It is completely symmetrical along its velocity vector.
posted by Catfry at 4:04 AM on April 1, 2011

Dear mathowie: please give everyone the ability to favorite one FPP twice. I pick this one.
posted by sneebler at 7:59 AM on April 1, 2011

Interesting that Arthur C. Clarke wrote a novel surrounding a space elevator based in Sri Lanka (albeit his home turf)... looking at that map, he couldn't have picked a better spot.
posted by crapmatic at 8:44 AM on April 1, 2011

"Somewhere in South Carolina/And gravity don't mean a thing."
posted by digitalprimate at 9:20 AM on April 1, 2011