The northern lights lit up the sky as far south as southern Wisconsin on Wednesday night during a moderate geomagnetic storm.

The G2 geomagnetic storm was caused by a solar eruption from sunspot Region 2403. The region is actually made up of multiple sunspots, each of which are many times the size of the Earth. “It contains an enormous amount of energy that, given a trigger, could ignite a large flare or launch a fast coronal mass ejection,” wrote our space weather expert Joe Kunches on Wednesday. “These are the waves of energy that cause power anomalies and brilliant aurora here on Earth.”

Just to the left of this spot is a very large coronal hole. Unlike sunspots with occasionally erupt with energy, coronal holes emit a constant stream of high-speed solar wind.

Interestingly, Joe writes, “for some yet unexplained reason, strong active regions tend to emerge near the boundaries of coronal holes. For example, one of the hot active regions during the famous Halloween Storms of 2003, Region 484, was located just ahead of a large coronal hole.”