I could never be a space weather forecaster. The aurora is just too unpredictable. Scientists at NOAA’s Space Weather Prediction Center work tirelessly examining solar images and spacecraft data and then lay it all on the line with a written forecast. I and many others receive those multiple updated forecasts in our email boxes several times a day .
Sometimes they nail it, and a solar blast delivers an aurora on or near the predicted time. Other times the crew misses the mark — the aurora appears, but it’s much weaker (or stronger!) than expected. Or nothing happens at all. I admire and appreciate their efforts. They have to deal with a capricious star and frankly, not enough information. The rest of us only have clouds to worry about.
Early Saturday evening (April 9), the forecast showed nothing special. There was only the possibility of “activity” — nothing on the storm-level — from 10 p.m. to 1 a.m. Under a moonless sky that would mean a modest glow very low in the northern sky visible northern North Dakota, Minnesota, Wisconsin, Michigan and possibly other states. But the moon was both high and bright Saturday night, so it would have easily washed out the meager light.
Instead, a G3 or strong storm arrived in its place with aurora easily visible in moonlight after the sky cleared around midnight from my location in Duluth, Minnesota. Even though wisps of high clouds smeared the view, it was still a good aurora with lovely crenulated arcs and lots of movement. I found a field with a nice view but getting there meant punching through foot-deep snow with every step. After stomping down a 1-foot-wide hole to stand in, it was time to enjoy the show.
I returned home to post an alert but couldn’t resist another look after moonset around 4 a.m. to see the lights in a dark sky. Much better! So was the snow. The top crust had set in the deepening cold (24°) and was now as firm as concrete and completely walkable. Such are the small joys of the late-night aurora seeker.
It sounds cliche, but no two auroras are alike. There are always similarities, but the pace, evolution, form and color vary each time. Not quite knowing what to expect means it’s hard to walk away. Who knows what might be next? Of course, I’m paying the price (a small one) for my lack of sleep, a mild headache I’ll remedy with a nap.
The cause of Sunday morning’s storm appears to be a coronal mass ejection that arrived on April 8 with little effect … initially. There’s speculation that strong magnetic fields flowing in its wake connected with Earth’s own magnetic field a day or so after arrival and sparked the sudden, strong display.
Right now, things have quieted down with minor storming (G1) in the offing for Sunday afternoon followed by quiet conditions Sunday night (April 10) when it’s dark over the U.S. and Canada. The moon continues towards full making any upcoming auroras tricky or impossible to see until April 19, when we enter the next evening moon-free period.
Never worry too much about the hour or the temperature. It’s all about being outside.
“Astro” Bob King is a freelance writer for the Duluth News Tribune.