A day after the Northern Lights lit up the skies over Illinois, the spectacle could be visible again as charged particles continue to hit Earth’s atmosphere.

According to the Space Weather Prediction Center, a geomagnetic storm continues to impact Earth, and forecast models suggest the arrival of those charged particles could cause the Northern Lights to be visible in Illinois Tuesday evening and Wednesday morning.

The latest estimates show a “K-index” of about 7.33 between 10 p.m. and 1 a.m. Central Daylight Time, and a “K-index” of 6.67 in the three hours before that.

According to the National Weather Service, the K-index shows “fluctuations in the Earth’s magnetic field” over a three-hour period. Anything above a five on the scale of 0 to 9 is considered a geomagnetic storm and can cause the Northern Lights to be visible much further south than normal.

In the event that the K-index is seven or higher, the Northern Lights can be seen as far south as Illinois and Oregon, according to officials.

Fortunately for Illinois residents, it appears Mother Nature will cooperate as the Northern Lights ignite Tuesday night and Wednesday morning. Mostly clear skies are expected during the overnight hours, although it will be quite cool outside, with lows in the upper 30s and lower 40s in areas outside of Chicago.

The best chance to see the Northern Lights is between 10 PM and 1 AM, but residents are encouraged to stay away from the city lights if possible and look toward the northern horizon for the best chance of seeing the spectacle.

The Northern Lights are enhanced when coronal mass ejections, or CMEs, erupt from the Sun and speed through space before hitting Earth’s atmosphere. According to the SWPC, CMEs are “large explosions of plasma and magnetized particles from the Sun’s corona.” These emissions grow larger as they approach Earth’s atmosphere and can cause geomagnetic storms upon arrival.

The Northern Lights are created when these 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.

The Northern Lights are generally only visible at high altitudes, but events like this week’s geomagnetic storm can make these particles visible over greater distances.