A gigantic collision of solar regions caused celestial light shows in the Northern Hemisphere. Are we looking for another showing of the Aurora Borealis?
FLAGSTAFF, Ariz. – Aurora Borealis? At this time of year? In this part of the country? Well, it wouldn’t be the first time this year.
After northern Arizona — and much of the Northern Hemisphere — was treated to a celestial light show last month, the cluster of sunspots that brought the aurora to Arizona has circled the star and is now headed back toward Earth.
‘It’s really cool to see this sunspot come into view again. It’s actually quite rare
that that happens,” said Dr. Joe Llama of Lowell Observatory in Flagstaff. ‘Most sunspots do not survive more than one complete rotation around the sun.’
Unfortunately, the chance that we will be treated to the Northern Lights this time is small. These sunspots are no longer busy consuming another part of the sun.
“Multiple areas of magnetic activity can erupt on the Sun, and they can essentially merge into one super sunspot region,” he explained.
When this giant sunspot cluster last visited our neck of the solar system, it was known as active region 3664 (AR3664). Catchy name, right? In early to mid-May, AR3664 collided and merged with another active region, creating a colossal barrage of radioactive solar flares from the ensuing tangle of magnetic fields.
“What happens is you get these very eruptive features,” Llama said. He said it was like this: “You take a rubber band and you twist and twist and twist and twist, and eventually it will break. And when it does, it ejects all this material into the interplanetary medium.”
This process caused the Sun to emit huge blobs of plasma, known as coronal mass ejections. When these solar events struck Earth’s magnetic field, they created a geomagnetic storm powerful enough to produce the Northern Lights in areas as far south as Arizona.
But the sun rotates quickly and takes about 27 days to make a complete rotation. That moved AR3664 away from us to the far side of the sun, giving it time to stabilize and break down. Now that it’s back with a new name – AR3697 – the region is smaller and less active.
>>Editor’s note: The above video is from a previously broadcast broadcast.
And unfortunately, “the best time for this sunspot to produce aurora here on Earth was actually about a day ago,” said Dr. Llama. He explained that the sunspots must erupt within a certain time frame before the material and energy they emit can pass through Earth’s orbit.
In May we were treated to class X solar flares, the largest of the categories. This time, AR3697 sent out a few X-class flares, but mostly M-class flares. While still several times larger than Earth, these are only about one-tenth as strong as X-class eruptions.
Even without an aurora in Arizona, those of us with an eye on the sky are still in for a treat in the years to come.
The sun goes through an eleven-year cycle from low activity to high activity and is currently reaching peak activity. Dr. Llama expects that we will reach solar maximum around July next year.
“While the sunspot coming around this time won’t produce an aurora for us here in Arizona, I would strongly encourage viewers and listeners to keep an eye on space-related news,” said Dr. Llama. “We are now entering solar maximum, so now is the time to keep an eye out for the aurora and keep an eye on these warnings.”
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