Rays of pale red and green aurora stripe the northern sky last night March 1, 2013. The tops of the rays reached about two fists high above the horizon. Photo: Bob King
Life can get frantic. That’s why it felt good deep down to watch the slow dance of the northern lights last night. The space weather dudes forecasted a small chance of their appearance, and indicators like the Kp index held steady at just below minor storm level for much of yesterday.
Patchy aurora in Cepheus and Cassiopeia last night. Pale green was visible with the naked eye, but the dimmer reds didn’t register in color except in the camera. Photo: Bob King
The aurora first appeared as little more than a faint glow near the northern horizon shortly before 10 o’clock. It lolled around pushing up occasional faint rays until moonrise. Unlike some other displays, the leisurely weave of this one slowed down my brain and made for a relaxing view. There’s a 10% chance of more minor auroras for the northern U.S. tonight.
Auroral activity is connected to the sunspot or solar cycle. When the cycle reaches its peak approximately every 11 years, we see gobs of sunspots and solar flares are frequent. Material blasted into space during explosive flares and other solar activity is largely responsible for the “juice” behind the northern lights.
In a recent NASA Science News article, solar physicist Dean Pesnell of the Goddard Space Flight Center explores what’s been happening with Solar Cycle 24, the one currently underway. Sunspot numbers shot up in 2011 and early 2012 and then dropped off later that year through early 2013. Peak cycle is predicted for May this year, so what gives?
All solar maxima aren’t created equal. Some are weak, some more energetic and sometimes we get two peaks instead of one.
The blue curve shows the actual sunspot count; the red is what was predicted. Recent sunspot numbers are falling short of predictions. Credit: Dr. Tony Philips and NOAA/SWPC
“The last two solar maxima, around 1989 and 2001, had not one but two peaks, says Pesnell. Solar activity went up, dipped, then resumed, performing a mini-cycle that lasted about two years. The same thing could be happening now.
The sun displays only small to medium-sized spot groups (labeled) in this photo taken by the Solar Dynamics Observatory at 10 a.m. CST today. Click to see full disk. Credit: NASA
“I am comfortable in saying that another peak will happen in 2013 and possibly last into 2014,” he predicts. Back in 2006 and 2008 a group of solar physicists including Pesnell gathered to forecast the next sunspot cycle maximum. They picked May 2013. In light of flagging solar activity, that now seems unlikely; the new forecast pushes that back to the fall of this year.
There’s one more wrinkle to this story. Pesnell has found similarities between Solar Cycle 14 in the early 20th century, which also had a double-peak, and the current on. If the Cycle 24 plays out in the same way, we might get a peak later this year and another in 2015.
Like the coyote in so many American Indian tales, nature has stealthy ways that only the watchful eye can untangle.