Photos Show Northern Lights in Rare Appearance Over North America

Millions of people were treated to an unexpectedly spectacular light show on March 23 as the aurora stretched across the U.S. and Canada, as far south as Colorado and New Mexico. The incredible lights were a result of a severe (category G4) geomagnetic storm in our upper atmosphere. The event was possibly caused by a cloud of solar plasma from a coronal mass ejection that skimmed the Earth on March 23. This G4 geomagnetic storm was the most intense in nearly six years, spaceweather.com reported.

Pictures of the lights were posted to social media by people across the U.S. and showed the range of different colors painting the night sky. "OH MY GOODNESS! INCREDIBLE #northernlights north of Des Moines, Iowa!!!!!!" tweeted meteorologist Nick Stewart. "This is totally worth freezing my hands for. Captured from 50km north of #Saskatoon about half an hour ago," tweeted another user named Gunjan Sinha. Auroras are caused by solar plasma or flares interacting with gas in the atmosphere. This makes them release light in ripples of color across the sky. "The colors in the aurora are the result of particles in the upper atmosphere becoming excited by collisions with particles coming from within the magnetosphere and some from within the solar wind," Brett Carter told Newsweek in February. He is an associate professor in space science at RMIT University in Australia. "The different colors are the result of electrons relaxing from different energy levels from oxygen (the most common reds and greens) and nitrogen (dark reds/blues)." The lights appear increasingly red in color further toward the equator, because observers can see only the upper parts of the auroras. "That red color is usually also rather faint, since you do not have that many of the oxygen atoms around at such high altitudes," Daniel Brown told Newsweek last month. He is an associate professor in astronomy and science communication at Nottingham Trent University in the U.K. "But, if you have a strong enough activity like we are getting now, there are enough exciting particles in the coronal mass ejections to interact with more oxygen and make the red brighter." The lights were also seen across Europe, as far south as Dorset in the southwestern U.K. Stronger geomagnetic storms cause the lights to stretch further away from the poles. They are seen further south in the northern hemisphere and further north in the southern one. Due to the recent spring equinox, auroras often appear in the northern hemisphere and southern hemisphere at the same time. Tasmania in Australia also got a glimpse of the southern lights. Other than the beautiful displays in the night sky, G4 storms can also have an impact on technology both on Earth and in orbit. These events can cause widespread voltage-control problems, and may cause spacecraft to have problems with orientation and tracking, according to the NOAA space weather scale.

"These storms can influence more than just the power grid infrastructure," Carter said. "The use of GPS can be impacted due to variations in the ionosphere. The orbits of satellites in low-Earth orbit experience increased atmospheric drag due to the swelling of the upper atmosphere." Do you have a tip on a science story that Newsweek should be covering? Do you have a question about the aurora? Let us know via science@newsweek.com.

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