ribbons of green pink purple northern lights stretch across the night sky above homes and lights of a sprawling town
Northern Lights, also called aurora borealis, dance in the sky over Tromso, Norway.

Colorful Northern Lights could be seen unusually far south in US states including New York, Illinois, and Oregon on Monday night and early Tuesday morning.

The reason for this brilliant display is the sun, which shot a giant eruption of charged particles toward Earth on Sunday.

The colorful Northern Lights, or aurora borealis, appear when electrically charged particles from the sun interact with molecules in Earth's atmosphere.

Northern Lights may appear unusually far south

Typically these dazzling green, red, pink, and purple lights only appear around the Arctic Circle, or around the South Pole (there it's called the aurora australis). That's because our planet's magnetic field lines channel the steady stream of particles, called the "solar wind," to the poles.

Solar Wind
An animation of the solar wind shows particles streaming from the sun towards Earth.

But when eruptions or other disruptive events occur on the surface of the sun, they can send an extra flood of solar wind shooting toward Earth, hypercharging the aurora and even pushing it closer to the equator.

A giant eruption covering 'over half the sun' shot at Earth

That's what's happening on Monday and Tuesday. A flood of solar particles is washing over Earth after a giant filament arced away from the solar surface and burst into space, shooting out an eruption of material from the sun's outer atmosphere, the corona.

This type of event is called a coronal mass ejection, or CME. NASA's Solar Dynamics Observatory caught it on camera, in the video clip below.

A gif od the sun during a coronal mass ejection.
A G2 coronal mass ejection shot out from the sun.

"I have been observing the sun professionally for over 50 years and this is the largest filament eruption I have seen," Keith Strong, a solar physicist who has worked for Lockheed Martin and NASA, posted on X, the platform formerly known as Twitter. "Note it covers over half the sun."

Where the aurora might appear tonight

The below map of the Space Weather Prediction Center's aurora forecast shows where late-night or early-morning sky watchers might be lucky enough to see the Northern Lights.

Red zones show where the aurora is forecast with high probability, green zones show low probability, and the red line indicates the southernmost areas where the aurora could appear on the northern horizon.

globe with north america showing and a red green halo where the aurora borealis might appear tonight over canada and the usa
Red zones are where the aurora is forecast with high probability, green zones show low probability, and the red line indicates the southernmost areas where the aurora could appear on the northern horizon overnight on September 18, 2023.

The CME began washing over Earth on Monday morning, about 12 hours earlier than originally forecast, a spokesperson for NOAA's Space Weather Prediction Center told Insider. So the forecast for overnight conditions could change, but for now, the auroral possibilities look promising.

"If things continue like this for the next five to eight hours, there should be good aurora viewing in the northern US," Mike Hapgood, a space-weather consultant at the Rutherford Appleton Laboratory in the UK, told Insider in an email.

The eruption is also predicted to generate a geomagnetic storm in Earth's upper atmosphere, which could cause blackouts in some high-frequency radio communications.

The National Oceanic and Atmospheric Administration categorizes geomagnetic storms from G1 to G5. Forecasters currently expect a G1 or G2 storm overnight, but there's a chance it could be as strong as G3, the NOAA spokesperson said.

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