Probably all of the events discussed above are measured from satellites. What we really want are whether (currents?) are induced in the ground (although I suppose Lowell has talked about things like heating of the outer atmosphere can cause (sudden) but miniscule changes in rotation rates of the earth by redistribution of angular momentum). So, if Canie wants to get into this in depth, looking at what changes occur at earth's surface might be a good ides. I'm pretty sure that there are observatories that measure this scattered around (probably not many, though). Much of what is measured in space are blocked or deflected by atmosphere (x-rays?) or earth's magnetic field (particles...) Chris