Northern Lights Moving South
The northern lights are most often seen in the Earth’s northernmost regions, but in recent months, they have been visible farther south. It’s not a fluke, scientists say, but part of a trend that will allow a wider swath of the world to get a rare glimpse of the phenomenon for the next few years.
The lights will be visible farther south because of a shift in the sun’s magnetic fields, which flip on an 11-year cycle between solar minimum and solar maximum. This phenomenon will peak in 2025, during the maximum phase.
“When we’re in the minimum part of the solar cycle, the sun is very quiet, basically nothing going on,” said Taylor Cameron, a Canadian Hazards Information Service scientist. “And then at maximum, we’ve got lots of solar flares, lots of coronal mass ejections. The sun is just much more active.”
The expanded visibility of the lights, created by activity in the sun’s magnetic field, has already begun, said Shannon Schmoll, the director of the Abrams Planetarium at Michigan State University.
The northern lights, or aurora borealis, are created when solar wind or charged particles from the sun interact with the Earth’s magnetic field, exciting atoms in the atmosphere.
Electrons jump to a higher energy level and release light — seen as the auroras — as they settle back down, she said. Oxygen in the atmosphere creates green or red light during an aurora, while nitrogen causes blues.
Usually, the auroras are most easily viewable in places like Scandinavian countries and Northern Canada. Every winter, tourists from around the world flock to Arctic locations, venturing into the snowy night to spot the phenomenon.
But over the past few months in the Northern Hemisphere, viewers have seen the auroras in southern England and Ireland, as far south in the United States as North Carolina, New York, Arizona and central California, and southern Ontario in Canada.
The best seasons to see the aurora are spring and fall, close to the equinoxes.
“That’s the same time in which sort of the Equator is totally flat with the rotational plane of the sun,” said William Archer, a mission scientist at the Canadian Space Agency.
Solar terrestrial events are measured by a Kp-index, which is a scale from zero to nine, Dr. Archer said. The higher the number, the more active the aurora.
A northern lights episode last month reached a Kp of eight. For central United States viewing, the Kp has to reach about seven or higher, he said. Darker areas away from city lights have the best visibility.
The U.S. National Oceanic and Atmospheric Administration operates a short-term forecast with the location and intensity of auroras.
Experts also recommend using SpaceWeather.com and SpaceWeatherLive.com as resources to hunt for the lights; AuroraMAX shows a livestream of the lights during winter months.
The Geophysical Institute run out of the University of Alaska Fairbanks provides forecasts for North America, Europe, and the Southern Hemisphere, where the lights are called aurora australis, or the southern lights, and where visibility has also expanded.
Trips to see the aurora often involve finding the perfect view, said Amy Hope, a managing director for the Aurora Zone, a tourism company in Britain.
Since the aural window has expanded, Ms. Hope has received messages from friends in Scandinavia who have seen the lights from their homes.
Even during solar maximum, tour groups will hunt for the best view.
“What’s so addictive about it — for want of a better word — is that it’s different every single time,” Ms. Hope said.
More dazzles as the sun’s magnetic fields shift.