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View Full Version : Earth like planet, gravity anomoly



Tzarkoth
2014-Oct-08, 02:18 AM
I recently read an article concerning a shift in the gravity field over the Antarctic.

http://globalnews.ca/news/1594500/antarctic-sea-ice-loss-causes-measurable-change-in-gravity/

Now, this got me to thinking.

In certain Fantasy novels I have read, although nothing specific springs to mind, there are areas called the Land of the Giants etc.

Could these areas, be the result of lower gravity fields. What would be the outcome if a planets iron core were off centre, or if section of the planets crust was significantly thicker, or more dense than other parts. Would it rotate about its axis normally, or would it wobble, fly apart, or become normallized over a few billion years? The Earth wobbles, through a combination of effects as I understand it.

But to be clear, what would be the result of say having the Earth's crust much thinner under, say Australia, and much thicker under, say Canada? ... and while we are in fantasy land, give Canada's section more heavy metals.

Jens
2014-Oct-08, 02:35 AM
The problem is, you don't get that much variation. From Wikipedia, you can see that the variation on the earth is from 976 to 983 Gal, so basically 10 parts in a thousand so like 1%. So the heaviest area is just 1% more than the lightest. That means that if you weigh 50 kg in the lightest place you'll weigh 50.5 in the heaviest, which isn't enough to make any difference.

John Mendenhall
2014-Oct-08, 02:53 AM
Worth noting that the headline is typical of general science reporting for the popular press. Sea ice just displaces its own weight in the water so there should be no measurable change in the mass creating the gravity. Duh uh. The articles are about continental ice loss which is a different matter.