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PHOTOS: Northern Lights glow on Wyoming’s horizon in wake of strong solar storm

Northern Lights seen on Wyoming's horizon. (NWS in Riverton)

CASPER, Wyo. — The Northern Lights were visible in the skies above Wyoming on Wednesday night and the National Weather Service in Riverton was able to capture some photographs of the display.

Wednesday night and early Thursday marked “[o]ne of the most intense displays of northern lights in years,” the Washington Post reported.

The sun has produced three outbursts of coronal mass ejections since Monday, according to Space.com. Such ejections can lead to geomagnetic storms on Earth. An alert of the possibility of geomagnetic storms capable of causing power grid fluctuations and spacecraft and satellite irregularities was in effect through Thursday morning, according to the National Oceanic and Atmospheric Administration.

Northern Lights seen on Wyoming’s horizon. (NWS in Riverton)

The so-called “Kp-index” measures “the disruption of the horizontal distribution of the geomagnetic activity” and gives a sense of how far south the Northern Lights may be visible, according to Wyoming Stargazing.

When the Kp-index measures 6 (on a scale of 0-9), the northern lights may be visible in Wyoming.

“If the Kp were to reach 7, it would be seen as far south as southern Utah and Colorado,” Wyoming Stargazing says. “The scale tops out at 9, and that’s when people in Mexico and Hawaii would be able to see them.”

The Northern Lights are unlikely to be visible in Wyoming on Thursday night, based on a forecast from the University of Alaska-Fairbanks’s Geophysical Institute. The Kp-index from 6 p.m. Mountain Time through the morning hours Friday is forecast at 4 or below.

When there is a chance to spot the Aurora, the University of Alaska-Fairbanks’s Geophysical Institute says that the best chance is the 3-4 hours around midnight.

“Since clear sky and darkness are both essential to see aurora, the best time is dictated by the weather and by the sunrise and sunset times,” the institute adds. “The moon is also very bright and can make it more difficult to view the aurora, so lunar cycles should be taken into account.”

The aurora refers to “a luminous glow seen around the magnetic poles of the northern and southern hemispheres,” the institute adds.

The appearance of the glow is caused by collisions between electrically charged particles “streaming out from the sun in the solar wind that enter Earth’s atmosphere and collide with molecules and atoms of gas, primarily oxygen and nitrogen.”

“When the electrons and protons from the sun collide with oxygen and nitrogen in the Earth’s atmosphere, they gain energy,” the University of Alaska-Fairbanks’ Geophysical Institute says. “To get back to their normal state, they release that energy in the form of light. The principle is similar to what happens in a neon light. Electricity runs through the light fixture to excite the neon gas inside, and when the neon is excited, it gives off a brilliant light.”

“The dancing lights of the aurora are seen around the magnetic poles of the northern and southern hemispheres because the electrons from the sun travel along magnetic field lines in the Earth’s magnetosphere. The magnetosphere is a vast, comet-shaped bubble around our planet. As the electrons from the solar wind penetrate into the upper atmosphere, the chance of colliding with an atom or molecule increases the deeper into the atmosphere they go.”