The Northern Lights may be seen this weekend in the continental U.S. after space weather forecasters predicted G2 or G3 geomagnetic storm conditions.
In the wake of several solar flares this week, coronal mass ejections from the sun are set to appear Friday, Sept. 13 and Saturday, Sept. 14. They follow red aurora visible as far south as California early on Thursday, Sept. 12.
The National Oceanic and Atmospheric Administration’s Space Weather Prediction Center released a Northern Lights forecast that suggests possible activity this weekend.
With Earth’s magnetic field already vibrating from the strong (G3-class) geomagnetic storm of Sept. 12, these impacts should be effective, according to SpaceWeather.com.
An X1.3 class solar flare was detected on Thursday, Sept. 12 at 09:43 UTC, suggesting more activity later this weekend and into next week
Only those in dark skies—away from urban light pollution—will likely see any aurora.
Northern Lights: Visibility
A G2 geomagnetic storm is being forecast, though take that with a pinch of salt—it could, in practice, turn out to be either a weaker G1 or a stronger G3.
- G2 storms are generally seen as far south as New York and Idaho.
- G3 storms can generally be seen as far south as Illinois and Oregon.
- G4 storms can generally be seen as far south as Alabama and northern California.
NOAA predicts geomagnetic storm conditions may continue through the weekend, though space weather is unpredictable and the forecast can change quickly. Skywatchers are advised to check NOAA’s aurora view line, which is available for tonight and tomorrow night, and its 30-minute forecast and X account, where the latest forecasts are posted. For those in the U.K., Lancaster University’s AuroraWatch website is invaluable.
Northern Lights: Kp Index
The predicted displays of aurora borealis have predicted Kp index of 6. Here’s how the Kp index works and what you’ll see, according to NOAA:
- Kp 6 to 7: “The aurora will move even further from the poles and will become quite bright and active. At this geomagnetic activity level, it might be possible to see the aurora from the northern edge of the United States.”
- Kp 8 to 9: “The aurora will move even further towards the equator, and it will become very bright and very active. These are the events that create the best aurora, and the extended auroral oval will be observable by most people. At these levels, the aurora may be seen directly overhead from the northern states of the U.S.”
Northern Lights: Causes
The solar wind causes the northern lights. It’s a stream of charged particles from the sun interacting with Earth’s magnetic field.
As charged particles strike Earth’s magnetic field, they accelerate down its magnetic field lines at the north and south poles to create ovals of green and red.
Aurora is typically seen in polar regions at around latitudes of 70 degrees north and south, but during extreme geomagnetic conditions—usually when CMEs arrive at Earth one after another, or in tandem—the auroral oval can bulge, with displays then seen as far as 40 degrees north and south.
Northern Lights: Solar Activity
Solar activity is currently at a 23-year high, with May 10’s extreme G5 geomagnetic storm being the most severe in the past two decades and possibly for hundreds of years. According to experts, the sun is approaching “solar maximum” this year or next. SWPC’s latest forecast is for it to happen between August 2024 and January 2025.
The sun has an 11-year cycle during which its magnetic activity waxes and wanes. Its level is calculated daily by counting sunspots. Sunspots are magnetic disturbances on the sun’s surface that can be as big as Earth. The number of sunspots on any day indicates how magnetically active the sun is.
Wishing you clear skies and wide eyes.
