How fast are magnetic fields?

[d3x0r]

1) an EM field is obviously limited to speed of light in formation... that is creating a current is definitely sub-luminal.


But; Gravity's propagation is definately faster than the speed of light... (not that creating/destroying gravity itself can be faster than light, so it's not a source of information transfer, since mass itself required to create a change in gravity is limited to sub-luminal speeds.


http://www.metaresearch.org/cosmology/speed_of_gravity.asp
"The same dilemma comes up in many guises: Why do photons from the Sun travel in directions that are not parallel to the direction of Earth's gravitational acceleration toward the Sun? Why do total eclipses of the Sun by the Moon reach maximum eclipse about 40 seconds before the Sun and Moon's gravitational forces align?" [/size]

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Although [/size]https://en.wikipedia.org/wiki/Speed_of_gravity would have you beleive that the effect travels at the speed of light...
'Gravitational Wave' such as is caused by stars exploding in theory travels at the speed of light; but that's a change in gravity due to masses changing.


Is there some sort of way one can detect the magnetic field of the sun in the case of an eclipse?   


There is some semi-related information by http://www.geek.com/chips/faster-than-light-radio-waves-could-revolutionize-computer-industries-821291/
but that's really about introducing spin to existing radio waves to encode more information than previously possible (since there's a 'spin' in addition to the amplitude changes)

"Called a polarization synchrotron, the device combines radio waves with a rapidly spinning magnetic field. The effect is described as "abusing the radio waves so severely that they finally give in and travel faster than light"."[/font][/size]

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that was half a decade ago and no real news beyond that.


But to have a magnet spinning that's strong enough to detect at a distance far enough to compare to the image of the magnet at the same point in time to see if there's any discrepancy? 


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Disrelated to the original question... it is interesting to ponder that an amount of mass in an area X outside of that area does not have the same gravitational effect as that amount of mass in a smaller area Y at the same distance of X ?  Or does it? 


Just a question since experiments like http://lisa.nasa.gov/ (LISA) or LIGO https://en.wikipedia.org/wiki/LIGO are looking for changes because of exploding stars...


Should experience such waves many many years before we actually see it happen... so it'll be hard to correlate... but other than that, since the same amount of mass (minus a tiny bit converted to energy from supposed nuclear explosion ) will still exist within an area of space relative to us.