Earth is in the path of multiple coronal mass ejections (CMEs) from the sun this week, which could mean the aurora borealis and australis will again light up evening skies over a larger than normal portion of the planet.
As of Sunday, NOAA’s Space Weather Prediction Center is forecasting a thirty percent chance of a strong geomagnetic storm for Tuesday.
What that means in lay terms is a whole lot of energetically charged plasma that exploded from the outer layer of the sun in recent days is about to reach us and crash into Earth’s magnetic field. This collision creates what’s called a geomagnetic storm, resulting in aurora and potential outages to certain electronic equipment, including satellites and components of the electrical grid on the ground.
The stronger the geomagnetic storm, the farther towards the equator the aurora may be seen as all that energy pushes them beyond their normal homes near the poles.
In the case of a G3, or strong, storm it may become possible to see the northern lights as far south as US states including Oregon, Iowa and Pennsylvania. The storm in May of this year that saw some of the most widespread auroral displays in decades was originally forecast as a strong G3 storm, but surprised everyone when it actually arrived as an extreme G4 event that was historic in its scope.
This week’s forecast is of lower confidence than what we saw in May, but still worth looking out for.
It’s being driven by a so-called “cannibal” CME, which is when one CME is overtaken by a faster such blast on its way to Earth. The faster cloud of charged particles swallows up the slower one and essentially merges with it.
A cannibal CME arriving Tuesday is what’s behind the strong geomagnetic storm alert, and there are other CMEs set to arrive later in the week that could make things interesting Wednesday and beyond as well.
Somewhat surprisingly, all of these CMEs are associated with moderate, M-class solar flares. We could also see some action this week or next from the region of the sun that unleashed the most powerful flare of this solar cycle last week, as well as a major CME that was not aimed in our direction.
All in all, it’s shaping up to be a week worth watching the sky. Check back with Forbes or a site like the SWPC for the latest aurora forecasts.
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