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Earth's magnetic pole has been known to switch sides in the past. https://en.wikipedia.org/wiki/Geomagnetic_reversal

"183 reversals over the last 83 million years... A brief complete reversal, known as the Laschamp event, occurred only 41,000 years ago during the last glacial period. ... Geologists first noticed that some volcanic rocks were magnetized opposite to the direction of the local Earth's field.".

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When this happens, does the magnetism "rotate" around the Earth, or does it fade out and fade back in reversed?

Closer to fading out and back in.

Does this mean anything for the protection the planet receives from cosmic rays or solar wind?

Definitely

https://m.phys.org/news/2012-11-cosmic-rays-reveal-event-ear...

Indeed. Some people believe these “unshielded” periods might had some influence on the evolution of the species. Without those, the rate of change is just not enough to get to humans...

I'm not contesting but merely interested in references.

Here's a gif from a 1995 supercomputer simulation of the reversal process - https://imgur.com/a/jgpZZBF "The tubes represent magnetic field lines, blue when the field points towards the center and yellow when away."

Original source: https://www.psc.edu/science/glatzmaier.html It took them a year of computing on a CRAY C90 and 2000 hours of processing.

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