If darkness, a clear sky and a geomagnetic storm coincide Thursday night, Canadians may be able to see the northern lights.

Blasts of charged particles from the sun, including the largest solar flare in over four years, may colour the sky with northern lights Thursday.

NASA reported that the class X2 flare erupted from the sun on Tuesday, and may reach the Earth Thursday.

It comes on the heels of two smaller, slower coronal mass ejections — bubbles of plasma from the sun — unleashed on Feb. 13 and Feb. 14.

What causes the aurora?

The northern lights or aurora borealis are caused by the interaction of charged particles from the sun with the Earth's magnetic field. That excites oxygen and nitrogen in the Earth's upper atmosphere and causes them to light up.

The aurora is usually best seen in the Arctic and Antarctic because that is the location of the poles of the Earth's magnetic field.

"They may put on an excellent show of aurora," NASA predicted.

The aurora borealis, or northern lights, are among the possible effects of geomagnetic storms produced from the interaction of the solar particles with the Earth's geomagnetic field.

Such storms can also disrupt radio communications, and China reported such disruptions through its official Xinhua News Agency Wednesday, according to Agence France-Presse.

Lorne McKee, a forecaster with Space Weather Canada, said that appears to be a result of the earlier flares, which did not affect Canada.


The faint edge of a halo coronal mass ejection, a bubble of plasma, can be seen as it races away from the sun towards Earth on Feb. 15. This was the largest flare in over four years. ((NASA))

Both Space Weather Canada and the Space Weather Prediction Center, run by the U.S. National Oceanographic and Atmospheric Administration, predicted that the largest flare would hit mid to late Thursday.

McKee said Canadians can check the Space Weather Canada for constant updates, and should keep their eyes open for the aurora Thursday night, provided there is darkness and the sky is clear.

John Manuel, a research scientist with the Canadian Space Agency, said the storm probably won't cause power outages like the large flare that knocked out Hydro-Québec's entire network in 1989. But he said it could damage satellites and suggested people who normally rely on a GPS, which uses satellites to navigate might want to bring a map as a backup.