A quiet sun spurs questions on future aurora

October 4, 2010

 

The sun’s sluggish activity over the last year has sent many faithful aurora watchers to the experts at the Geophysical Institute. They want to know why there are so few aurora-filled nights and when they can expect the bands and curls of light to reappear in the night sky. Unfortunately, there isn’t an easy answer to their questions.

 

The aurora is dependent on the sun. Generally the solar wind provides a slow, steady breeze of solar particles to collide with Earth’s magnetosphere, but it’s the perturbations in this breeze — the occasional solar flare or coronal mass ejection, which sends a tsunami of energized particles toward Earth — that create the vibrant, active aurora seen near Earth’s poles.

 

The sun’s activity typically follows an 11-year cycle. Dirk Lummerzheim, a professor emeritus of aeronomy at the GI, says we’re at the minimum of that cycle now, but a quick bounce-back isn’t predicted. He says it will probably be a slow ascent. 

 

On Aug. 1, 2010, a coronal mass ejection burst off the sun, igniting a moderate flash of auroral activity. From vantages in Canada and along the U.S./Canadian border, the northern lights were visible on several evenings. The recent solar event and the subsequent aurora renewed hope that aurora-filled nights may be in the not-so-distant future.

 

So will winter 2010 bring more aurora? Scientists are cautiously optimistic. 

 

“Even though the aurora predictions are a lot like reading tea leaves at the moment, I’m still daring to make predictions, “ Lummerzheim said.

 

“There is cause for optimism,” said Charles Deehr in late August. “The aurora is going to increase in activity for the next three or four years.” Deehr, a professor emeritus of physics and a longtime forecaster at the institute, says aurora-filled nights will become more prevalent, but the change will be gradual. Therefore, aurora watchers will have to remain patient.

 

Lummerzheim and Deehr, both retired, update the GI’s online aurora forecast from afar. The scientists base their predictions on available solar wind data and many years of combined research on the phenomenon. 

 

To view the recent aurora forecast, visit http://www.gedds.alaska.edu/AuroraForecast/.