The sky over an unusually wide swath of the northern hemisphere lit up with a brilliant display of color overnight into Monday morning, and some places may have a second chance to be dazzled.
From Sunday night into Monday, the display was visible as far south as Iowa in the United States, as well as in parts of southern England, scientists said. From late Monday into early Tuesday, the lights could be visible again in parts of the United Kingdom, Canada and the northern United States, according to forecasters.
The phenomenon, known as the aurora borealis or northern lights, occurs when particles emitted by the sun collide with particles that are already trapped around Earth’s magnetic field, and can often be seen from parts of Iceland, Canada and Alaska.
But on Friday, the sun let off a large burst of energy, said Robert Steenburgh, a space scientist with the Space Weather Prediction Center at the National Oceanic and Atmospheric Administration. (These bursts are also known as coronal mass ejections.)
“The sun spit off a big blob of plasma,” Mr. Steenburgh said. The burst of energy, which has its own magnetic field, had been moving through space and reached Earth’s magnetic field on Sunday, when the two collided to create a geomagnetic storm, he said. “It got our magnetosphere pretty revved up.”
When this happens, the aurora can be seen closer to the Equator, Mr. Steenburgh said. Such events are not that uncommon, with about 100 occurring every 11 years, he said, adding that the storm can also disturb high-frequency radio used at sea and by airlines.
On Monday, the geomagnetic storm eased, Mr. Steenburgh said, noting that this would decrease the magnitude of any visible aurora. People in Canada, Alaska and in parts of the northern tier states, he added, were most likely to catch a second glimpse.
Viewing of the phenomenon can also be less optimal as summer approaches, he added. “You’re going to have longer days, so nighttime opportunities will be fewer to catch these things,” he said.
Some parts of the Southern Hemisphere were also treated to a spectacular light show from late Sunday into early Monday. (There, the phenomenon is called aurora australis.)
For those unaccustomed to seeing the night sky illuminated by streaks of green or red, an aurora borealis — in folk tales, the northern lights have been associated with spirits and divine forces — can inspire awe, or even fear.
In 1872, an article in The New York Times described a sky glowing so intensely that “many persons supposed a great fire was raging back of Brooklyn.” In 1941, hundreds of onlookers gathered on the boardwalk of Rockaway Beach, N.Y., to view the phenomenon, and in 1929, many readers of The Times called the paper to report the dazzling sight.
On Sunday, the storm created a spectacular show of light.
Forecasters with the National Weather Service office in Riverton, Wyo., shared images of a sky painted with deep purples and bright greens. The northern lights could also be seen over Maine and parts of Wisconsin, as well as in Toronto.
In Europe, the northern lights were seen over southern England, where streaks of magenta and yellow illuminated the skies above Stonehenge.
Christine Hauser contributed reporting.