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Keep your fingers crossed for clear skies: the U.S. Space Weather Prediction Center (SWPC) is calling for a strong geomagnetic storm, which could produce the northern lights.
Typically, we get the northern lights after a strong solar flare, where the magnetic fields get entangled and then snap, releasing intense bursts of radiation, which can disrupt high-frequency radio signals here on Earth.
The flare is usually followed by a coronal mass ejection, or CME. The CME is a fast-moving stream of particles burped out by the sun that travels very fast along the solar wind.
If Earth is in its path, the particles interact with our magnetic field and molecules in the atmosphere, providing a beautiful light show in the sky.
There were three CMEs unleashed over the past two days. Two will give Earth a glancing blow, while the third, which happened on Wednesday, is directed toward Earth, according to the SWPC.
The glancing blows may have been responsible for the northern lights, also known as the aurora borealis, being seen as far south as Minnesota on Wednesday night.
The SWPC is calling for a G3 geomagnetic storm, which is considered strong on its scale of G1 to G5.
As usual, there’s a caveat: these storms are difficult to predict.
“There is a fair measure of confidence in a Earth-directed aspect to this CME and a moderate level of confidence in timing of the CME arrival—which we anticipate with a range from as early as Thursday evening to Friday morning [Eastern time],” the SWPC wrote yesterday.
“However, as is usual with these events, we have less confidence in the intensity of the resultant geomagnetic storm upon eventual CME arrival and passage. Therefore, this G3 Watch represents our forecast based on potential. “
So, just how strong it could be isn’t known.
The other issue is that there’s a full moon, which will drown out any faint northern lights. But there’s still a chance, as they were visible on Wednesday when the moon was in a similar phase.
The most important part is that you get to a location with a good view of the northern horizon.
And, once again, remember that things need to line up for a good display: the solar wind must be very fast, and the auroral hole — along which the particles travel — must be tilted south. The further south it is, the farther south they will be visible.
You can see if the aurora is visible in your location by using apps like Aurora Alerts, and My Aurora Forecast.
