It's been a while, but I did take an astrophysics class that got into the solar system's electromagnetic dynamics. As I recall, the sun is constantly shedding

It's been a while, but I did take an astrophysics class that got into the solar system's electromagnetic dynamics. As I recall, the sun is constantly shedding ionized material known as solar wind. This plasma carries the magnetic field from the sun with it. From "above", the magnetic field looks like a giant spiral with the sun at the center. It sounds like the earth may have moved through a particularly dense spot of the solar wind which interacted strongly with the Earths magnetic field. This would probably also cause unusually strong auroras. That's about the extent of my knowledge (plus I'm on my phone and it's a bit difficult to get into a lot of detail). I'm sure someone else around here can correct me and/or give more insight.