A moderate solar storm will crash into Earth today (September 27), which could cause auroras to dance across the sky at much lower latitudes than usual. As a result, the Northern Lights may be visible tonight in the northern United States, including the states of New York, Wisconsin and Washington, according to the National Oceanic and Atmospheric Association (NOAA).
The storm, which is made up of charged solar particles flowing through space, can also cause satellite outages and some “power grid fluctuations” at high latitudes (particularly above the 55th parallel north, a line that traverses Canada, Northern Ireland and much of Russia), said NOAA.
However, the storm will remain relatively weak, classifying as a G2 level storm on a five-level scale with G5 being the most severe. Only in category G4 and above storms are widespread power outages expected, according to NOAA.
Related: Where to See the Northern Lights: Northern Lights 2021 Guide
Solar storms are a common form of space weather, occurring when coronal mass ejections (CMEs) leave the sun’s outer atmosphere and collide with Earth’s magnetic shield. CMEs are huge droplets of plasma (electrically charged gases that make up all the stars in the universe) that escape from the sun’s atmosphere and rise through space at hundreds or thousands of miles per second. According to NOAA, it takes between 15 and 18 hours for a CME to reach Earth after leaving the sun.
Up to four CMEs could be destined for Earth at this time, NOAA said.
What happens next depends on the strength of each CME. Benign storms, like the one predicted for today, collide with the Earth’s magnetic shield, compressing it slightly. During the collision, charged solar particles slide along the lines of our planet’s magnetic field toward the poles, colliding with atmospheric molecules along the way. These churning molecules release energy in the form of light, glowing in stunning bands of red, green, blue, and yellow. This is how auroras happen.
Generally, the stronger a storm, the more visible the resulting auroras are at low latitudes. But really strong G5 storms can do a lot more. An infamous geomagnetic storm of 1859 known as The Carrington Event disrupted Earth’s magnetosphere so severely that telegraph cables burst into flames. Another storm, which struck in March 1989, shut down the Canadian province of Quebec for nine hours and caused power outages across North America.
Tonight’s storm will be nothing compared to past disasters, according to NOAA predictions, but it won’t be the last we see. The sun is approaching a period known as solar maximum, the most active part of its 11-year cycle. During maximum, the sun’s magnetic field, which controls CMEs and other solar weather conditions, is at its strongest, resulting in more and stronger solar storms.
Solar activity is projected to gradually increase through July 2025, at which point it will slow down and approach a new solar minimum, according to NASA.
Originally posted on Live Science.