Get ready to map your geoid. But why?
? It's a sphere, right? Well not exactly. OK, so it's a bit flatter at the poles and bulges in the middle. An oblate spheroid? That's a better approximation, but still not accurate. Ah, so you mean you want to include all the lumps and bumps, like mountain ranges, deep ocean trenches, land masses, etc? Not exactly.
The world, as it turns out, is -shaped. The geoid is probably best described as Earth's 'true surface' - what it would be if the oceans were allowed to run free without land, currents or wind getting in the way. A map of the geoid would be irregular but very smooth, with the same at every point.
If you know what your geoid looks like, you can establish a universal system for the height of everything on Earth. And if you know that, you can do things like measure very accurately how much ice we're actually losing from major ice sheets, or figure out how the oceans distribute heat around the globe. And if you know that, you can better understand how our climate works.
What Goce does, from ESA's YouTube channel. Weird soundtrack and no commentary, but the animations might be helpful.
So how do you measure your geoid? Last month, the European Space Agency launched the Goce satellite, the vanguard of an exciting new programme of Earth observation. Goce, which (sort of) stands for 'Gravity Field and Steady-state Ocean Circulation Explorer', carries a set of incredibly sensitive instruments that will do exactly that.
Happily, it turns out this week that the incredibly sensitive instruments have all survived the usual rattling and banging involved in rocket launches and are all working well. . And probably a pivotal moment in our understanding of global warming as well.
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