Toronto skywatchers might want to keep an eye on the northern horizon this weekend. A geomagnetic storm is expected to intensify aurora activity across Canada after a solar eruption earlier this week, and while nothing is guaranteed, the setup could give parts of southern Ontario a rare chance to spot the northern lights!
The National Oceanic and Atmospheric Administration (NOAA) is now carrying a G2 watch from March 19 to 21, and Canada’s Space Weather service has also posted a storm watch for Thursday afternoon into Friday morning.
For Toronto, the most active periods are expected to arrive roughly Thursday evening through after midnight, with another bump late Friday night into the pre-dawn hours Saturday. Forecasts can shift quickly, though, so there’s still real uncertainty around the timing.
The weather may matter almost as much as the geomagnetic forecast. Environment Canada’s Toronto forecast calls for partly cloudy skies Thursday night, then cloudier conditions Friday, while Saturday looks better during the day before cloud periods return at night. Looking across the country, The Weather Network says the timing of this storm could favour central and western Canada for the strongest displays, while northwestern Ontario appears to have some of the better clear-sky potential in the eastern half of the country.
The science behind the northern lights is surprisingly straightforward (and honestly, somewhat geeky). According to NOAA, the Sun is constantly throwing off charged particles in the solar wind, and when a stronger burst of solar material reaches Earth, it can dump extra energy into our magnetic field. That energy helps accelerate particles into the upper atmosphere near the poles, where they collide with oxygen and nitrogen and release light, creating the Aurora Borealis (aka, the northern lights). Green is the most common aurora colour, while reds, pinks, blues and purples can show up, depending on which gases are hit and at what altitude.
If you’re still interested in chasing the lights over the next few nights, head somewhere dark, keep your eyes on the northern horizon, and watch the forecast right up until you leave. The best aurora is typically seen between 10 p.m. and 2 a.m. away from city lights.
