Posted on 05/11/2007 4:37:41 PM PDT by blam
Satellites solve mystery of low gravity over Canada
20:16 10 May 2007
NewScientist.com news service
Kelly Young
The GRACE satellites have detected changes in the gravitational field over regions of Canada that can be attributed to the crust bouncing back after the melting of a glacier 20,000 years ago and convection in Earth's mantle (Illustration: Science/M Tamisiea)
If it seems Canadians weigh less than their American neighbours, they do – but not for the reasons you might think. A large swath of Canada actually boasts lower gravity than its surroundings.
Researchers have puzzled for years over whether this was due to the crust there rebounding slowly after the end of the last ice age or a deeper issue involving convection in the Earth's mantle – or some combination of the two.
Now, ultra-precise measurements taken over four years by a pair of satellites known as GRACE (Gravity Recovery and Climate Experiment) reveal that each effect is equally responsible for Canada's low gravity. The work could shed light on how continents form and evolve over time.
GRACE, a joint mission of NASA and the German Aerospace Center, was launched into space in 2002. The two spacecraft fly 500 kilometres above the Earth, 220 kilometres apart. Using a microwave ranging system, the two spacecraft can measure distance differences between them as tiny as a micron.
That allows them to measure tiny changes in the distribution of mass – and hence gravity – on the Earth. For example, if the leading spacecraft were to encounter an area with more gravity, it would be pulled ever-so-slightly closer to Earth than the trailing spacecraft, and that distance can be measured.
Crushing weight
A team led by geophysicist Mark Tamisiea, who performed the work while at the Harvard-Smithsonian Center
(Excerpt) Read more at space.newscientist.com ...
Sooooooooo, are they saying Canada doesn’t suck as much as the rest of the world?
I thought it was due to light weight politicians.
Bush’s fault?
We’ve known about the rising Canadian sheild for decades. It’s one of the reasons for the cliffs around lake Superior.
Bushs fault and carbon emissions fault.
When they say they have several theories as to what is happening, it means they don’t really know what is going on.
Global warming caused by those 20,000-year-old industries.
No, silly. It is because Canada is close to North Pole and that is how Santa’s raindeer fly. Pffft. Who needs scientists?
Since you have so many Hollywood celebrities you have more Scientologists.
Since you have more Scientologists you have fewer Thetans.
Since you have fewer Thetans you have less gravity.
Airheads?
“can be attributed to the crust bouncing back after the melting of a glacier 20,000 years ago”
Wow, that is a really long bounce!!!
Oh NO! Global Warming melts glaciers, and destroys gravity. We’re all going to float away!
So Canadians are lightweights? Figures.
Don't be surprised if some global warming theologian actually makes that statement.
Hm...
Interesting.
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