Thursday's solar flare could potentially cause a colorful aurora in the northern part of the United States, but researchers won't know until it gets here. While you could spend all night and looking to the heavens, the Space Weather Prediction Center has put together a map and chart to help you know whether you'll be able to see it or not—here's how to use them.
Scientists use a measure of "Kp," or geomagnetic activity, to determine how far south people will be able to see the aurora, known in some places as the "Northern Lights." According to Phil Chamberlin of NASA's Solar Dynamics Observatory, the Kp of Thursday's solar flare is expected to be between six and eight (out of 9)—if the Kp remains weak, only people in the northernmost states and Canada will be able to see the aurora, but if it's closer to 8, people as far south as Washington, D.C. will be able to see the aurora.
Follow the Space Weather Prediction Center's Kp chart, which is updated every five minutes with the last three hours' data, and compare it to the map to determine whether you'll be able to see the lights. Kp is expected to spike sometime in the next 24 hours as the charged particles reach Earth. In the United States, aurora are relatively rare occurrences, but in the aftermath of the "Halloween Storms" of October, 2003, people as far south as Florida reported seeing auroras.
"I've never seen one with my eyes, it's definitely on my bucket list," Chamberlin says. "I don't know if I'll stay up all night for this, but I'm going to keep checking this index."
Jason Koebler is a science and technology reporter for U.S. News & World Report. You can follow him on Twitter or reach him at firstname.lastname@example.org