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Gravity Map of Earth
dr3vil writes "Interesting results have been published by the GRACE (Gravity Recovery and Climate Experiment) project, of the various gravity anomolies that exist at various places on Earth. The BBC report gives a good overview. Fascinating for me, a resident of California, to see us apparently sandwiched between a high and a low spot. Maybe that helps aids the tectonic flows around here?"
BTW, if you want to know how much gravity differs (and how damn sensitive these sats are), look at this chart:
/ 03 _07_GRACE.html
http://www.csr.utexas.edu/grace/gallery/gravity
And note the range of the legend -60 to +60 mGal.
Because variations in gravity are very small, units for gravity surveys are generally
in milligals (mgal) where 1 mgal is one thousandth of 1cm/s
Thats damn sensitive.
-molo
Using your sig line to advertise for friends is lame.
Maybe that helps aids the tectonic flows around here?
Seems to me that the techtonic flows cause, rather than are caused by gravitational differences. Less mass in one area == less gravity, and so forth.
Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. (Einstein)
From what I understand (very little), we already have very sensitive equiptment detecting submarine presence.
Again, I'm trying in vein to remember the source, but I recall listening to a Radio program on how satellites are used to note peculiar wakes in the ocean, and can even differentiate between a submarine and a large whale.
I can't find anything technical on google, but apparently The chinese government was interested enough to steal the info.
"Inattention makes clowns of us all" -Bean
Can't work. Basically you are measuring the denisty/mass differences in large areas (lets even say you can do it down to the centimeter though). So an area that has high mountains, highly dense subsurface is going to have a higher pull from gravity.
A submarine with neutral boyancy (not going up or down, just level) would displace an equivalent volume of water, therefor not change the gravity field around it.
That said, there is no reason why we can't us other things like detecting the change in magnetic flows because a large nuclear reactor just went underneath, and things like that
I have mod points and I am not afraid to use them
If the sub is moving, their is a layer of compressed water on one side, and a layer of slightly less compressed water on the other side (kind of like how radar sees a moving volume). Not to mention any bubbles generated by the spinning prop(s) out back decreasing the density of the water significantly. Question is; can we detect it fast enough to matter? Knowing where a sub was 30min ago is useless.
IIRC, magnetic harmony has already been reached between sub and ocean. I think that was something they did back in the 50's or 60's. Not 100% on that though...
Sub launches are detected by traditional means; optical satellites, or men/women on the ground in the area.
2 days means nothing in a world full of ICBM's tipped with multiple nuclear warheads.
http://stommel.tamu.edu/~baum/reid/book1/book/node 32.html
I guess you missed that simple physics class
"Eve of Destruction", it's not just for old hippies anymore...
If you were to fly over the red areas, you would be tugged ever so slightly downwards;
;-)
As opposed to? Yes, in our normal experience, gravity acts as an attractive force.
the blues mark regions where the planet's attraction is much weaker.
"Much weaker"? The entire range corresponds to about 0.1% of Earth's mean gravitational attraction. For comparison, the apparent decrease in local gravity at the equator due to centrifugal force FAR exceeds the differences shown in the linked article (by a factor of about 5, in fact). And even that only changes the local apparent force to 9.78m/s/s.
Then again, I suppose we have separate careers called "journalist" and "scientist" for a reason.