Look for the Northern Lights Tonight: Aurora Borealis Has a Season, and It Just Started

Yahoo

04-03-2025

Aurora borealis is one of the coolest astronomical events that we can see with the naked eye. It makes the sky glow beautiful colors, and auroras are just random enough to be exciting occurrences. But they may not be as random as we all think: Historical data suggests that aurora borealis has seasons where they are more likely to occur than other times of the year. The spring equinox is one of those times, and it's right around the corner.
Read more: Spring Equinox Is Almost Here: Have You Heard the Egg-Balancing Myth?
The idea that aurora borealis has "seasons" comes from data compiled by NASA astrophysicist, Dr. David Hathaway. According to the data, the northern lights are more likely to show up in March, April, September, and October. Those are the months closest to the spring and autumn equinoxes -- the time of year when the sun crosses the equator and delivers almost equal amounts of daylight to the entire planet.
Hathaway's data is the latest, but it's not the first. Per Earth Sky, Aloysius Cortie, an English Jesuit astronomer, published research on the link between equinoxes and auroras in 1912. Later, Sydney Chapman and Julius Bartels included the idea of a twice-yearly aurora borealis season in their book Geomagnetism, which was the de facto textbook on the topic for decades.
Read more: Check Out These Breathtaking Northern Lights Photos From Aurora Watchers
That means over a century of scientific consensus says that the northern lights are more likely to show up over the next couple of months as we reach the spring equinox, and then again in September and October as the seasons change again.
The key to the whole thing seems to be how equinoxes work. During the winter and summer months, half of the Earth is tilted away from the sun, therefore making aurora borealis less likely (unless the geomagnetic storm is particularly strong).
"The equinoxes are the transition points between which hemisphere is tilted toward the Sun," Shannon Schmoll, director of the Abrams Planetarium, told CNET in an email. "At this point, the Earth's magnetic field is at a more favorable angle, closer to perpendicular, that allows easier interaction of the charged solar particles with the Earth's magnetic field and atmosphere."
Read more: Why Is The Aurora Borealis More Frequent All of a Sudden?
According to Dr. Schmoll, the Earth's magnetic field has a north and south pole, just like any magnet. The sun does as well. Dr. Schmoll says that science is still figuring out the specifics, but in short, the poles of the sun and Earth line up better during the equinox, which is conducive to more frequent auroras.
"The relative positions of all the magnetic field lines around this time make it easier for Earth to interact with the sun's charged solar wind, resulting in aurora," Schmoll says.
The equinox effect -- also known as the Russell-McPherron effect -- is also entirely separate from the 11-year solar cycle that the sun runs through. Currently, the sun is at its maximum for this cycle, which increases the odds of aurora borealis showing up even more.
The sun's increased activity and the equinox effect have already been observed recently. Late in 2024, aurora borealis lit up the night sky for much of September and October, with some being visible way further into the US than is typical.
'Tis the season, as they say, and aurora borealis is already making its presence known. Per the Space Weather Prediction Center, an aurora is happening Tuesday, March 4, for one night only.
It won't reach down as far as Texas like some of the more epic auroras did last year, but it should be a pretty good display for folks in the northern US.
The aurora is predicted to reach as far south as Iowa, with people in Montana, North Dakota, and Minnesota getting the best views. It'll also be partially visible in Wyoming, South Dakota, Wisconsin, Maine, Michigan and parts of New York, New Hampshire and Vermont.