How It Works
"When we see the northern lights, it's driven by a large eruption on the sun," explains Aurorasaurus founder and space scientist at NASA Dr. Elizabeth Macdonald. "And those happen more frequently, though not exclusively, during solar maximum times."
As you can imagine, solar storms and the aurora can get complicated and Macdonald cautions against oversimplifying maximum and minimum, saying, "Solar maximum is not a specific point in time. It's really like several years that the sun is more active." Likewise, the minimum isn't a day or a month, but a years-long stretch of time.
"The northern lights are less frequently seen during solar minimum, which we are approaching now," says Macdonald. "But, no, that doesn't mean you can't see the northern lights on clear dark nights at very northern latitudes like Fairbanks, Alaska and several other places at northern latitudes. You can basically see them all winter there, despite the fact that the solar cycle is at a minimum.
"The solar cycle being at a minimum doesn't mean there are no storms, and it doesn't mean there isn't what I like to call 'everyday aurora.' It will just remain at high latitudes and less frequently be visible to lower latitudes, where most of us live."
You may remember in early September there were a series of intense eruptions on the surface of the sun. It caused the northern lights to be seen as far south as Michigan and other parts of the northern continental United States. The eruptions occurred at an intensity that hadn't been seen in many years, but during a time when we're approaching minimum. Larger individual events can still take place even as the overall frequency drops.
To further complicate matters, the solar cycle isn't constant. The maximum and minimum activity of each cycle varies compared to other cycles. As Dr. Nathan Case notes, most models predict we are headed toward "a period of particularly weak solar cycles, where the solar maximum of each cycle will not result in much solar activity." That means the next maximum probably isn't going to be as active as the maximum we're just leaving in the rearview telescope.