Tag Archives: active region

Solar Cycle 25 Underway, First Activity Reported

Northern Light Now – The long absence of large solar flare activity may come to an end soon as solar cycle 25 active regions start to appear. The last C-class flare occurred on May 15, 2019 from active region 12741. In the 7 months since, there have been only 19 active regions numbered as the Sun has been in the depths of the cyclic solar minimum. For aurora hunters, the only source of activity has been from an occasional filament eruption and High Speed Streams originating at Coronal Holes. However, over the last several months there are indications that the next solar cycle is picking up and activity will return over the next year. Aurora hunters should start looking forward to the next season.

The Solar Cycle lasts about 11 years. During each cycle, activity increases for about five and a half years. The monthly count of active regions and sunspots visible on the Sun increases until Solar maximum. At maximum, the Sun’s polarity flips and activity slowly tapers back into solar minimum over the remaining five and a half years in the cycle. Currently, the Sun is in the least active part of this cycle and as a result there have been fewer and weaker aurora displays over the last year.

Chart Shows Active regions by month with solar minimum highlighted
Chart Shows Active regions by month with solar minimum highlighted

Solar Cycle 24 (SC24) started in January of 2008 and peaked in July of 2013 and is ending now. At peak, there were nearly 300 active regions numbered in 2013. There were only 22 new active regions numbered in 2019. There is normally an overlap between the end of one solar cycle and the beginning of the next. Of those 22 active regions numbered in 2019, only 17 actually belong to SC24, the other 5 are part of Solar Cycle 25.

When Will Solar Activity Increase?

By the start of the next northern hemisphere aurora season! Aurora hunters can expect the 6 to 9 months ahead to continue to have very low solar activity. During the minimum between SC23 and SC24 there were about 30 months with fewer than seven active regions numbered. In the current minimum, the last month with more than seven active regions identified was September of 2017 – or 27 months ago. This is an arbitrary threshold, but can prove useful when making an estimate. Projecting out and assuming the same length of solar minimum, May or June should be the first month with 7 newly numbered active regions of Solar Cycle 25.

While there won’t be much activity from CMEs originating at active regions, it will certainly be possible that there will be activity from coronal holes. Attentive space weather fans will have noticed over the last couple years that Coronal Holes are the primary driver behind aurora activity during solar minimum. It is possible there will also be activity from filament eruptions (link to what happened today). Overall, the frequency of storms should be about the same over the last 6 months as it will be over the next 6 months – that is to say, not much.

The frequency and magnetic complexity of SC25 regions will continue to increase. With each new region, the likelihood of the next C-class flare increases. Seasoned aurora hunters know that long duration C, M and X class flares are one of the keys to a good northern lights display. Of course, a more complex AR could develop at any time and produce an strong flare, it is just far less likely during solar minimum. So keep watching the data and keep watching the active regions.

Happy Hunting

Active Region 2712 Enters Earth Strike Zone

Northern Lights Now – Active Region 2712 produced a beautiful B class flare On May 24 as it rotated into view in the northern hemisphere of the Sun. The region held together and grown slightly and has now produced a C-class flare that measured C2.77. Today the region has started to develop some mixed magnetic fields and shows potential to produce more C-class flares. It is now in the Earth strike zone.

AR2712 produced this flare on the East limb as it was rotating into view.
AR2712 produced this flare on the East limb as it was rotating into view.

Keep an eye on this region over the next several days. If it generates an eruptive flare and a CME it could impact Earth’s space weather later this week. Here’s a time lapse of the region show in SDO’s HMI colorized magnetogram.

Happy Hunting

Late September Features To Watch On The Sun

Northern Lights Now – It has been two weeks since the X-class flare that active region 2673 released as it rotated out of view on the western limb. In that time space weather and aurora activity on Earth has been slowly waning. As that active region rotates back into view it will be renumbered, probably as 2682, and space weather forecasters will be watching to find out how it’s magnetic structure has changed. In addition to the returning active region, there are two coronal holes that may impact Earth’s Aurora activity over the next 7-10 days.

Coronal Holes

A small coronal hole was pointed towards Earth on Sept 21, 2017. Notice in the AIA 211 image below that the majority of the coronal hole is to the south of the solar equator. This time of year, the earth is actually about 7 degrees north of the solar equator. The size of this hole and it’s location to Earth’s south decreases the magnitude of anticipated impact. There is a slight chance for KP4 or KP5 on Sept 24 as the high speed wind from the hole travels near Earth, but SWPC has not issued a geomagnetic watch

Southern Coronal Hole pointed towards Earth on Sept 21
Southern Coronal Hole pointed towards Earth on Sept 21

A second, bigger, coronal hole is approaching the Earth strike zone and will likely have a bigger impact on Earth’s geomagnetic activity September 27th to 30th. This coronal is in the northern hemisphere and has a history of producing high solar wind speeds at Earth on it’s previous rotation. The hole has developed a southern “arm” that crosses the Solar equator. The hole is now “transequitorial,” another indication that Earth will likely be in the high speed wind stream. It seems likely this will prompt a G1 or possibly G2 storm watch later this week.

Another Coronal Hole is approaching the Earth Strike Zone. This one looks more likely to impact Earth's Space Weather
Another Coronal Hole is approaching the Earth Strike Zone. This one looks more likely to impact Earth’s Space Weather

The Return of AR 2673

The large complex active region that blasted 3 X-class flares and numerous M-class flares two weeks ago is completing it’s rotation around the back side of the Sun. While it was on the opposite side of the Sun, LASCO detected at least one major CME from it, but it his been less active over the last several days. As it rotates into view, forecasted will get their first glimpse of whether it has maintained it’s magnetic complexity.

We won’t know until 24-48 hours from now, but if it is still complex, there could be additional M-class flares over the next week. Stay tuned to find out!

Old AR 2673 is rotating into view
Old AR 2673 is rotating into view

Happy Hunting