Illinois Could See Northern Lights Again Tonight – NBC Chicago

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 these charged particles could cause the Northern Lights to be visible in Illinois Tuesday evening and into Wednesday morning.

The latest estimates show a “K-index” of about 7.33 between 10:00 p.m. and 1:00 a.m. Central Daylight Time and a “K-index” of 6.67 in the three-hour window 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 0 to 9 scale is considered a geomagnetic storm and can cause the northern lights to be visible much further south than usual.

In the event that the K index is seven or more, the northern lights can be seen as far away as Illinois and Oregon, according to authorities.

Luckily for Illinois residents, it appears Mother Nature will cooperate as the Northern Lights shine Tuesday evening and into Wednesday morning. Mostly clear skies are expected during the overnight hours, although it will be quite chilly outside, with lows in the upper 30s and low 40s in areas outside of Chicago.

The best chance of seeing the Northern Lights may be between 10 p.m. and 1 a.m. However, residents are advised to stay away from city lights if possible and look toward the northern horizon for the best chance of seeing the spectacle.

The northern lights are amplified when coronal mass ejections (CMEs) erupt from the sun and race through space before hitting Earth’s atmosphere. According to SWPC, CMEs are “large explosions of plasma and magnetized particles from the solar corona.” These ejections increase in size as they approach Earth’s atmosphere and can cause geomagnetic storms when they arrive.

The Northern Lights occur when these charged particles collide with the Earth’s magnetic field, interacting with atoms and molecules in the upper atmosphere and creating bright, wavy colors in the sky.

The Northern Lights are generally only visible at high altitudes, but cases like this week’s geomagnetic storm can cause these particles to be visible at greater distances.