Strong solar activity may soon trigger auroras farther south than usual
By Katie Hunt and Ashley Strickland, CNN
(CNN) — The northern lights could grace skies farther south than usual this week because of a solar storm that may affect Earth, according to the US National Oceanic and Atmospheric Administration’s Space Weather Prediction Center.
The center issued a strong geomagnetic storm watch, known as a G3 — the third highest level out of five — for July 29 to July 31. Activity is likely to peak on Tuesday as aurora-causing solar flares and coronal mass ejections from the sun reach Earth, according to NOAA.
Strong geomagnetic storms are infrequent, the Space Weather Prediction Center said, but they’re more common than the G5, or extreme, geomagnetic storm that occurred on May 10 and May 11. That event unleashed auroras that dazzled many places around the globe that don’t normally see the ribbons of colorful, dancing light.
If the predicted G3 conditions occur, auroras could be visible as far south as Illinois and Oregon, the Space Weather Prediction Center said.
Coronal mass ejections are large clouds of ionized gas called plasma and magnetic fields that erupt from the sun’s outer atmosphere. When these outbursts are directed at Earth, as they were this weekend, they can cause geomagnetic storms, or major disturbances of Earth’s magnetic field.
As the sun nears solar maximum — the peak in its 11-year cycle of activity, expected this year — it becomes more active, and researchers have observed increasingly intense solar flares erupting from the fiery orb.
In the United Kingdom, the Met Office said on Monday that auroras may be visible in Scotland over the next three nights, with a chance of a G3-level storm. In Australia, the Bureau of Meteorology said a coronal mass ejection arrival on July 30 could result in “significant geomagnetic activity and visible auroras during local nighttime hours.”
Viewing auroras is a game of chance, but the fickle phenomenon is more likely to be visible within an hour or two of midnight, according to the Space Weather Prediction Center.
To get the best vantage point, find a place with dark skies away from artificial light and look north (or south in the Southern Hemisphere). Cameras can capture auroras even when the naked eye cannot. To get the best shot, use a tripod and share your observations with community science site and NASA partner Aurorasaurus.
What causes auroras
Increased solar activity causes auroras that dance around Earth’s poles, known as the northern lights, or aurora borealis, and southern lights, or aurora australis.
When the energized particles from coronal mass ejections reach Earth’s magnetic field, they interact with gases in the atmosphere to create different colored lights in the sky.
The solar storm that reached Earth in early May was the strongest in two decades, according to NASA, and the barrage of solar activity created one of the strongest displays of auroras on record in the past 500 years, with auroras visible in the southern US and northern India.
Sunspots, which release the solar flares and coronal mass ejections that trigger auroras, are driven by the star’s strong and constantly shifting magnetic fields.
Alerts issued by NOAA’s Space Weather Prediction Center and other agencies help the operators of power grids and commercial satellites to mitigate potential negative impacts from a solar storm.
The geomagnetic superstorm in May had a minimal impact on critical infrastructure, however, a G5 storm that occurred in 2003 resulted in power outages in Sweden and damaged power transformers in South Africa.
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