The northern lights could be visible from the United States this Thursday, treating people at northern latitudes to a fantastic glowing display, according to a forecast from the Geophysical Institute at the University of Alaska, Fairbanks.
If skies are clear, “active auroral displays” may be visible low on the horizon in places including Great Falls, Montana; Pierre, South Dakota; Madison, Wisconsin; Lansing, Michigan, and Portland, Maine. The spectacle will also be visible in Canada.
Though the lights don’t typically reach peak visibility until midnight, it’s “worth stepping outside” to try and catch a glimpse, Daniel Verscharen, a space and climate physicist at University College London, told Business Insider’s Marianne Guenot last week, when auroras were predicted to reach some northern states.
The Geophysical Institute updates its forecast daily at 8 p.m. Eastern time, and it can change quickly, Business Insider notes.
The northern lights, or aurora borealis, are a glowing display that appears green, red, blue or purple in the night sky. The breathtaking phenomenon comes from solar wind, or the constant stream of ions that flows from the sun’s surface to Earth. When these charged particles near our planet, they get pulled toward Earth’s magnetic poles—and some can get “trapped” there, according to National Geographic. In the atmosphere, the ions knock into oxygen and nitrogen atoms, causing a release of energy that we see as the northern (or southern) lights.
The auroras typically create an oval over each of the magnetic poles. But during major geomagnetic storms, which are driven by intense solar activity, the auroras expand and can be seen from the U.S., according to the National Oceanic and Atmospheric Administration’s Space Weather Prediction Center.
In April, for example, the northern lights dazzled viewers as far south as Texas, with spectators in California and Colorado catching sight of the rare, widespread phenomenon.
And events like this are becoming more common: The sun’s 11-year solar cycle could peak as soon as next year, increasing the frequency of severe solar storms and making the auroras visible farther away from the poles, writes the Associated Press. During solar storms, more solar wind hits Earth’s atmosphere, making the auroras easier to see, according to Business Insider.
The intensity of geomagnetic activity is measured by the planetary K index. The index ranges from zero to nine, with high numbers representing more activity and, as a result, more visible auroras.
The University of Alaska, Fairbanks, forecasts a planetary K index of two to three for the next couple of days—but on Thursday, it could rise to six. When the index is six or seven, “the aurora will move even further from the poles and will become quite bright and active,” perhaps becoming visible “from the northern edge of the United States,” according to the Space Weather Prediction Center.
If you plan to look for the lights, it’s best to be away from the artificial glare of cities. The aurora borealis is better seen from higher elevations and when no clouds or precipitation can obstruct your view, per NPR’s Ayana Archie. A full moon can also obscure the aurora, making its colorful glow appear less bright.
Editor’s note, July 11, 2023: This article has been updated to reflect a more current forecast from the University of Alaska, Fairbanks, showing that most aurora activity on Thursday will be over Canada and the northernmost U.S. states, a smaller area than previously predicted.