A day after the Northern Lights lit up the skies over Illinois, the spectacle may be visible again as charged particles continue hitting Earth’s atmosphere.
According to the Space Weather Prediction Center, a geomagnetic storm is continuing to impact Earth, and forecast models suggest that the arrival of those charged particles may cause the Northern Lights to be visible in Illinois on Tuesday night and into Wednesday morning.
The latest estimates show a “K-index” of approximately 7.33 between 10 p.m. and 1 a.m. Central Daylight Time, and a 6.67 “K-Index” in the three-hour window prior.
According to the National Weather Service, the K-index shows “fluctuations in the Earth’s magnetic field” over a three-hour period. Anything over a five on the 0-to-9 scale is considered to be a geomagnetic storm, and can cause the Northern Lights to be visible much further south than usual.
In the event the K-index is seven or greater, the Northern Lights can be seen as far south as Illinois and Oregon, according to officials.
Fortunately for Illinois residents, it appears that Mother Nature will cooperate if the Northern Lights fire up on Tuesday night and into Wednesday morning. Mostly clear skies are expected throughout the overnight hours, though things will get quite cool outside, with lows in the upper-30s and low-40s in areas away from Chicago.
The best chance to see the Northern Lights may be in the 10 p.m. to 1 a.m. window, but residents are encouraged to get away from city lights if possible and to look toward the northern horizon for their best chance of seeing the spectacle.
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The Northern Lights are enhanced when coronal mass ejections, or CME’s, erupt from the sun and speed across space before hitting Earth’s atmosphere. According to the SWPC, CME’s are “large explosions of plasma and magnetized particles from the Sun’s corona.” Those ejections expand in size as they approach Earth’s atmosphere, and can cause geomagnetic storms when the arrive.
The Northern Lights occur when those charged particles hit Earth’s magnetic field, interacting with atoms and molecules in the upper atmosphere and producing brilliant and wavy colors in the sky.
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The Northern Lights are generally visible only at high altitudes, but instances like this week’s geomagnetic storm can cause those particles to be visible across greater distances.
