DON’T MISS: Geomagnetic storms: When should we look up and when should we worry?
What is happening here?
We have not seen any major solar flare activity as of late, nor have there been any notable coronal mass ejections (solar storms).
This opportunity for us to see the Northern Lights stems from a phenomenon known as a co-rotating interaction region.
Basically, there are two types of solar wind. The first is the normal, sedate flow that is constantly streaming away from the Sun, at every moment of every day. This occurs simply from particles escaping from the top of the Sun’s atmosphere (the corona) into space, and is comparable to a light breeze.
This infographic describes what a Co-Rotating Interaction Region is, how it forms, and how it can impact Earth. (NOAA SWPC/Scott Sutherland)
Click here for a zoomable version of the infographic above.
The second type originates from coronal holes — large, dark regions of the Sun’s atmosphere where the magnetic fields have peeled back, exposing the Sun’s surface directly to space. The solar wind streaming out of a coronal hole is not as dense as the normal solar wind, but it is faster, and the particles carry more energy, resulting in a much more ‘blustery’ flow.
A co-rotating interaction region forms right at the boundary between these two types of flow, where the leading edge of the fast stream runs into the trailing edge of the slower stream. There, the higher energy particles hit the slower solar wind flow and become trapped, resulting in a buildup of them, over time.