Solar physicist Phil Scherrer, also at Stanford, describes what happens: "The sun's polar magnetic fields weaken, go to zero and then emerge again with the opposite polarity.
This is a regular part of the solar cycle." A reversal of the sun's magnetic field is, literally, a big event.
However, the advantage of paleomagnetic dating is that we can use it on different rocks from those susceptible to our ordinary methods of absolute dating: while most radiometric methods usually require igneous rocks, paleomagnetism can be measured in sedimentary rocks.
Changes to the field's polarity ripple all the way out to the Voyager probes, on the doorstep of interstellar space.As the field reversal approaches, data from Wilcox show that the sun's two hemispheres are out of synch.