The aurora borealis could be visible in large parts of Canada this week: Here’s what to know

Scientists say the aurora borealis is expected to be visible in much more parts of Canada than usual this week, due to the possibility of a geomagnetic storm. The phenomenon could begin as early as Friday.

According to the latest forecast from the US National Oceanic and Atmospheric Administration (NOAA), the aurora is likely to be visible across most of Canada. Only parts of the east coast of Nova Scotia and Newfoundland in the south, and some northern islands near Greenland, are out of range.

NOAA charts show that the chance of seeing the aurora will be highest in parts of the Prairies, the interior of British Columbia, and northern Ontario, Quebec and Labrador starting Friday night.

The rare phenomenon is associated with something called a coronal mass ejection (CME), when a large amount of plasma and magnetic field is ejected from the sun. The event could involve billions of tons of material traveling at speeds between 250 and 3,000 kilometers per second, the agency said.

Although the CME formed on August 5, its effects took days to reach Earth and are expected to enter the atmosphere by the end of the week.

On Earth, a CME can cause geomagnetic storms that can sometimes disrupt technologies such as power grids, pipelines and GPS systems. NOAA said this week's event was "generally manageable" and that a side effect would be a wider-than-normal view of the aurora borealis.

"Events of this magnitude are not uncommon," a warning issued Wednesday said.

According to NOAA's Geomagnetic Activity Index, the aurora borealis is expected to reach a 6 out of 9 on Friday night, which is in the "moderate" to "active" category.

Storm activity is also forecast at "moderate" at most, which could trigger alerts in some power systems and damage transformers if prolonged.

The geomagnetic storm is expected to weaken to "minor" levels Friday through Saturday, with the aurora score reaching 5 and visibility again limited to more northern latitudes.

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