NLN Aurora Briefs – October 20, 2015

Aurora Brief Number 1 of 14
Next Brief: NLN Aurora Briefs – October 21, 2015

Today on the Sun:

Active Region 2436 remains the biggest and most magnetically complex region on the solar disk. Over the last 24 hours it produced the majority of the solar flare, and a couple C-Class flares. It increased in size and in total number of sun spots in the period. Keep an eye on this regions as it rotates into the Earth-facing portion of the Solar Disk, it will likely produce additional flares. Here’s an animated GIF of Active Region 2436 showing the mixed polarities that give it the Beta classification and the recent growth in the last couple frames.

Animated GIF 3 days of magnetogram
Active Region 2436 (Beta-Gamma) in colorized Magnetogram

Active Region 2434 grew in size over the last day as well. It added several new spots on the southern edge of the primary spot and maintained it’s Beta status.

2003 on the Sun:

Over the next two week’s the NLN Aurora Brief will chronicle the “Halloween Solar Storm of 2003.” In 2003, during the declining phase of Solar Cycle 23, a period of major storms erupted over a period of several weeks. On this date in 2003, active region 484 started grew just over 4-fold in area from 240 millionths to 1000 millionths and developed delta spots. It produced the first X-class flare of the period measuring at X1.1. An image of AR484:

AR484 moved onto solar disk
Active Region 484 rotates on to the Eastern portion of the disk before explosive growth

Happy Hunting!

Scandinavian Northern Lights in October

This afternoon Burcu Basar (@BurcuBasarBlog) asked a question on Twitter:

Great question! We hear it often. The answer needs to be more than 140 characters.

The short answer is yes. There are a number of reasons Norway, Sweeden and Finland are terrific travel location for aurora hunters. But surprisingly, this has nothing to do with there aurora activity in October – it comes down to it being the right balance of warm (or at least not insanely cold) and dark.

The longer answer:

Solar storms arrive at Earth in a pattern governed by activity cycles on the Sun which are completely independent of the position of Earth or the season on Earth. Solar storms and aurora are just as likely to happen in October as in any other month.

The solar cycle can be used for determining how likely it is that your visit to a higher latitude location will coincide with an aurora show. This 11-year cycle governs the number of active regions and sunspots on the sun. Generally speaking, when there are more sunspots, solar storms from flares are more likely and aurora are more likely. So, a trip to Scandinavia during the peak of the solar cycle is more likely to reward an aurora hunter. The current solar cycle, “cycle 24”, is now in it’s declining phase, but there are still plenty of nights with aurora in store over the next several years. Here’s a graph showing the progress of the current solar cycle:

Graph of Solar Cycle 24
Solar Cycle Progression as of Sept 2015

Because a solar storm can arrive any time of the year, and at any time of day, the best place to be is where it is dark for a larger percent of the day. In the northern hemisphere, this means September through March, in the southern hemisphere March through September are the best aurora hunting months.

It also has to be clear to see the aurora because they are above the clouds. So, once you’ve picked a place to visit, choose a time of year where it is more likely to be clear skies.

In Vermont, where NLN is based, we frequently hear that August is the best time of year for northern lights – which goes entirely counter to the previous paragraphs. This discrepancy is due to weather. In August is it summer, its is warm and people are camping. People spend more time outside at night, and see more aurora. In the winter it’s cold and people huddle by their fireplaces at night, so they don’t even notice the aurora going on just outside their door. This leads to a perception that summer is a better time of year to see aurora.

Autumn seems to be the most comfortable and rewarding time of year to hunt aurora. The nights get longer, and the temperature hasn’t dropped too much yet.

So yes – go visit Scandinavia during October. Even if you don’t see the lights, it’s a wonderful place to visit.

Happy Hunting