Mapping our planet's gravity

[n2doc]

ESA
GOCE's map shows how density variations affect Earth's gravitational field, ranging from low density (blue) to high (red).


Mapping our planet's gravity
The European Space Agency's GOCE satellite has delivered a beautiful map of Earth's gravity field that will also serve important scientific purposes for years to come.

GOCE, which was launched in March 2009, stands for "Gravity field and steady-state Ocean Circulation Explorer." Its mission is to do high-resolution measurements of gravitational field variation across the entire globe, and particularly the oceans. The gravity map helps scientists produce a precise "geoid," an elevation map that shows how high ocean levels would be if the water were perfectly still. When you plug that data into computer models, you can get a better sense of how other forces, such as climate, affect ocean circulation. Thus, the readings from GOCE should give us a better fix on the effects of global climate change.

The new GOCE map was presented this week at an ESA symposium. Coincidentally, Space News quotes GOCE's managers as saying that the satellite has suffered an unusual computer-chip glitch. However, they say an onboard backup system should keep the low-flying probe in operation for the rest of its scheduled two-year survey mission.

Such visualizations can answer questions that have fueled many a science-fiction plot in the past. For example, what would happen if the earth stood still? ESRI's Witold Fraczek uses GIS analysis and comes up with a surprising answer: Much of North America, Europe and Russia would go underwater, and the rest of the globe's land masses would merge into one big equatorial supercontinent. Once you read "If the Earth Stood Still" in ArcUser magazine, you'll be grateful that gravity and particularly centrifugal force really, really work.

http://cosmiclog.msnbc.msn.com/_news/2010/06/30/4589097-mapping-our-planets-gravity

[tridim]

1. I think that map is more intriguing if you read it as "space/time distortions"

Yes, I know it's the same thing.

[Geoff R. Casavant]

2. So gravity is the least around India?

I forget, does that mean time speeds up or slows down in India?

I say it slows down. I've eaten my share of curries, and I can tell you from experience it sometimes feels like an eternity afterwards.

[AlecBGreen]

3. the stronger the gravitational field

the slower time moves for you

If you were able to perch on the edge of a black holes event horizon (super-powerful gravitational field) time would slow to a crawl. You could watch the evolution of the universe as it unfolds before your eyes. An observer looking at you would see you motionless, apparently frozen in time.

[AlecBGreen]

4. the stronger the gravitational field

the slower time moves for you

If you were able to perch on the edge of a black holes event horizon (super-powerful gravitational field) time would slow to a crawl. You could watch the evolution of the universe as it unfolds before your eyes. An observer looking at you would see you motionless, apparently frozen in time.