We are at Solar Maximum: What does that mean? – Alaska Photography Tours, Private Guiding & Classes

The sun is the driving force behind the aurora borealis. The sun goes through a roughly eleven-year cycle, where it transitions from a Solar Minimum to a Solar Maximum. We have a roughly 400-year understanding of what these cycles have looked like.

Solar cycles going back to 1600. Pre-1700 data is derived from anecdotal reports.

There are two key signatures that indicate we are at Solar Maximum. One is the frequency of sunspots. During Solar Minimum, sunspots rarely occur, sometimes over 200 days apart. But during Solar Maximum, they occur frequently. These small, dark holes play a crucial role in producing geomagnetic storms when they form solar flares, and those flares break off into space creating a Coronal Mass Ejection (CME). So, scientists look to when we have peaked in the frequency of sunspots as one sign of Solar Maximum.

The other key signature that we have reached Solar Maximum is when the sun’s magnetic poles reverse. If such a thing were to happen on Earth, the results would be potentially catastrophic. But for the sun, it is business as usual.

On October 15, 2024, the NOAA Space Weather Prediction Center and NASA issued a joint statement indicating that we had reached Solar Maximum.

Current solar cycle progression plot, February 6, 2025

But does not mean that we will stop seeing the aurora borealis? No, contrary to what you may see in news reports. While CMEs will occur less frequently, they will still occur. But they are only one factor that causes the aurora borealis.

Another solar behavior that creates the aurora borealis is a Coronal Hole. Like sunspots, they are cooling areas on the sun. But unlike sunspots, they are rather large, and they are not short-term phenomena. Coronal holes can stay open and active for months and even years. While they may not fling plasma out into space like a CME, they are constantly spraying the sun’s wind out into space. These coronal hole high speed streams can spark active aurora borealis displays and last for several days, as the sun rotates and the Earth passes through the stream. While coronal holes can occur on the sun at any time, they occur more frequently around Solar Minimum.

And that leads to another thing that can cause the aurora borealis – the regular activity of solar winds. The sun is constantly “blowing” its wind out into space. With those winds come the sun’s magnetic charge, known as the Interplanetary Magnetic Field. When the polarity of that magnetic charge (measured in a unit called “Bz”) is negative, and the strength of that IMF is high (measures in a unit called “Bt”), we can see the aurora borealis.

This certainly does mean that the aurora borealis will be seen less frequently in lower latitudes as we transition to Solar Minimum over the next five years. The large geomagnetic storms that allowed for several nights of good viewing in 2024 for the Lower 48 states were the result of a CME, so caused by active sunspot regions. Northern latitudes, like Alaska, will continue to see the aurora borealis. Regular solar winds and active coronal holes will continue to spark aurora displays. During the two previous periods of Solar Minimum in 2008 and 2019, the aurora was still seen frequently in Alaska. Generally speaking, the aurora will also remain fairly active for at least the next two years if prior solar cycles are a good indication.