People in at least 17 states may have a chance this week to glimpse the northern lights, which are typically seen in Earth’s northernmost regions.
The Geophysical Institute at the University of Alaska at Fairbanks forecasts high auroral activity on Thursday in Midwestern states like Minnesota, Wisconsin, Michigan and Indiana.
The aurora will be visible “low on the horizon” across Chicago, with the city light pollution making it harder to spot.
The colorful spectacle occurs when particles from the sun collide with gas molecules in Earth’s atmosphere. Thursday’s high auroral forecast is because of a solar storm, when there’s more particle activity, according to the Geophysical Institute.
When particles collide with nitrogen and oxygen in the atmosphere, they gain energy that is released in the form of light. And depending on the intensity of the energy, the type of gas molecule and the altitude, colors range from vibrant green to intense purple.
The dancing lights occur around the northern and southern poles because particles from the sun travel along Earth’s magnetic field lines. In the northern hemisphere, the lights are known as aurora borealis. In the southern hemisphere, it’s the aurora australis.
Between now and 2025, the lights will be visible to more of the northern hemisphere, the institute says, because of the sun’s 11-year cycle variation, which refers to how sunspots change over time. We’re nearing the peak year of 2025, when chances of seeing the aurora at lower latitudes are the highest.
Michelle Nichols, director of public observing at Chicago’s Adler Planetarium, said this particular cycle has been more intense than what had been predicted.
“It’s outperforming the predictions, which is great, that’s great for us,” she said. “That means we might get a chance to see things a little more often than the last several solar maxima.”
Nichols said the best place is an area with dark skies, which won’t be possible with city lights. In Illinois, there’s the Green River State Wildlife Area about two hours west of Chicago.
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But for the best views, Nichols suggests traveling to northern Wisconsin, Minnesota, North Dakota, northern Michigan or the Upper Peninsula. Even after traveling, there’s no guarantee the lights will match the forecast.
“They’re very, very, very hard to predict,” she said. “They may turn out stronger or weaker than what was predicted.”
Aurora strength is measured in Kp, ranging from zero to nine, with nine being a strong geomagnetic storm. Thursday night is forecast for Kp level 6.
According to the Geophysical Institute, the best time to watch for the aurora is between 9 p.m. and 3 a.m., but Nichols said this also isn’t guaranteed.
Despite all the uncertainty with Thursday’s light show, Nichols said it makes her happy that more people have been interested in the night skies, whether that’s the northern lights or upcoming eclipses.
“I really just am glad people are interested in looking up at the sky,” Nichols said.
