Chance of northern lights for Halloween

TORONTO – This Halloween, trick-or-treaters may get a light show to set the mood, courtesy of the sun.

A coronal mass ejection (CME) – a release of plasma and particles – left the sun’s surface on Monday, propelled by an M4-class flare.

Solar flares are measured by the amount of x-rays they emit, going from C, M and to the strongest, X.

When particles ejected from CMEs reach Earth, they interact with our magnetic field, producing northern lights, or auroras. Strong CMEs can cause radio blackouts and disrupt communication satellites.

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The sun unleashed an X-class flare – its fourth in a week – on Tuesday.  It also released another CME, however, this one is unlikely to have any effects on our magnetic field, as it was from a sunspot that was turning away from Earth. However, analysts from the National Oceanic and Atmospheric Administration are continuing to analyze the ejection to see if there’s any chance that it will affect Earth.

And if you’re wondering when or where you can see them, visit NASA’s Space Weather Prediction Center’s (SPWC) three-hour plot. A Kp index of 4 or more can be visible throughout Canada. A Kp index of under that and it’s better to be either further north or in a dark-sky location.

So if you have clear skies on Halloween night, keep an eye on the sky and you may get an treat.