There was a powerful geomagnetic storm over the weekend, resulting in beautiful displays of the northern lights from Canada down to the U.S. And there’s a possibility that the colourful curtains in the sky could be visible once again on Monday night.
The northern lights, or aurora borealis, occur when particles from the sun are carried along by fast-moving solar wind. Often this occurs due to a coronal mass ejection, or CME. This is a large expulsion of particles from the sun that travel faster than normal on the solar wind.
One of these CMEs hit Earth on Saturday, resulting in auroras seen all over the world.
The show continued into Sunday during daylight hours in Canada but then waned. But we are still feeling the effects of the CME interacting with our magnetic field, which means we may still get a show.
The strength of a geomagnetic storm is measured using the Kp Index, ranging from one to nine. The higher the number, the stronger the storm.
On Sunday, the Kp Index went as high as eight, but it fell to five by early Monday. Although it has dropped, that doesn’t mean the show is over. But it’s likely that it won’t be as powerful or intense as this weekend’s display.
As Chris Ratzlaff, a seasoned aurora chaser from Airdrie, Alta., and the co-founder of the ever popular Alberta Aurora Chasers, said, there’s “lots of potential [and] lots of uncertainty.”
“The probability is not high because there is uncertainty about the composition of the tail end of the CME,” he said. “If conditions in the tail end of the CME remain favourable, then our odds for aurora will improve.”
Forecasting the northern lights is notoriously difficult. There are numerous conditions that need to be met, including how fast the wind is moving and whether the auroral oval — along which these particles interact with molecules that produce the colours of the lights — tips south, in our favour.
The further south the hole dips, the further south the aurora are seen. And, as of Monday afternoon, the auroral oval was tipping south, in our favour.
To see them, you should look north. For those further south in Canada, such as in southwestern Ontario, it’s best to have a clear line of sight to the northern horizon.
The other thing that many Canadians may have to deal with that could hamper any chances of seeing the northern lights is the smoke that is covering many parts of the country as forest fires spread in Western Canada.
If the northern lights do show up Monday night, don’t expect an incredible display like the one from last May or last October. If it happens, this will likely be weaker.
