Map of the Galaxy, with our sun's position : http://www.atlasoftheuniverse.com/milkyway.html
Its center is full of void that emits light, you say ?
Edit : gaz that emits light, my bad.
A summary of what is Earth's magnetic field : http://www.abc.net.au/science/articles/2011/11/09/3359365.htm
And like the summary concludes, the reversal doesnt happen in a single day. Disturbances ? sure, but minimal.
Now as to why it doesnt happen in a single day, you can get a heachache from trying to decider this : http://www.science27.com/Earth/index.htm
Scientists dont even agree with each other : this one says reversal wont happen. Whatever.
But the point is : Earth's magnetic phenomenon cannot be compared to a single magnet.
Even if it did happen in a single day, we'd face this : http://www.sciencebits.com/NotReallyAProtection
So the only real problem we'd face would be the loss of atmosphere blown out into space along with solar wind.
And we wouldnt lose it all, not all at once. Took ages for Mars (but I'm tired of finding links).
Lastly, you said "Coincidentally the Mayan Calendar predicted the event to be in 12-21-12." And I said they
couldnt predict anything because astrology is blind to what lies after that date. And the superstitions goes : cant
predict = no future = end of the world.
Edit : This convo is turning meaningless. We both agree there are gonna be disturbances, where we differ is only how big
those disturbances are gonna be. I quit.