Saturday 17 November 2018

AR12727 - The Last Sunspot of Cycle 24? - 17th November

The current HMI image is typical of solar minimum.  On the solar equator there is active region 12727, quite possibly the last sunspot grouping of cycle 24.  Magnetic bands on the solar equator are slowly cancelling out with this activity; the active region is also preceded by a patch of plage closer to the limb.  Polar faculae are also visible as bright points, here there are coronal holes currently too.
In the last couple of solar rotations there have been signs of activity in northern higher latitudes on our star that showed reverse magnetic polarity.  This reversal in polarity is what differentiates solar cycles.  

Given that cycle 24 was a double peaked, with the northern hemisphere preceding the southern hemisphere, it is rational to assume that we should start to see the first signs of cycle 25 in the solar northern hemisphere.  Indeed only a week ago a small emerging flux region recently had a few small pore spots that had reversed polarity compared to cycle 25.  Pretty much all of the solar models are predicting cycle 25 will be weaker than 24 with a lower average sunspot number.  

The international sunspot number forecast from the Royal Observatory of Belgium made at the start of this month suggests we will see an uptick in solar activity as cycle 25 kicks in early in 2019.  I would speculate that given these double peaked solar cycles and that cycle 24 had the northern hemisphere peaking over 3 years before the southern hemisphere, with cycle 25 forecast to be weaker that it may well be that the frequency of the hemispherical peaks may well be longer in between.  In which case the activity of recent rotations is indeed cycle 25 activity.   It will be interesting to see how the ROB updates it's next prediction early in December.  It could well be that we are already seeing the uptick in graph they are predicting.