Over the weekend, a small sunspot materialized in the sun’s northern hemisphere, then, hours later, vanished again. Such an occurrence is hardly unusual during solar minimum when sunspots are naturally small and short-lived. However, this ephemeral spot was noteworthy because its magnetic field was reversed–marking it as a member of the next solar cycle.
Shown above is a magnetic map of the sun from NASA’s Solar Dynamics Observatory on Nov. 17th. Two sunspot groups visible at 21:00 UT are inset.
Note sunspot AR2727 just north of the sun’s equator. It is a member of decaying Solar Cycle 24, the cycle that peaked back in 2012-2014. Next, compare its magnetic polarity to that of the other, unnumbered sunspot high above it. They are opposite. According to Hale’s Law, this means the two sunspots belong to different solar cycles. The high latitude sunspot appears to be a harbinger of Solar Cycle 25.
Solar cycles always mix together at their boundaries. Indeed, ephemeral sunspots possibly belonging to Solar Cycle 25 have already been reported on Dec. 20, 2016, and April 8, 2018. Now we can add Nov. 17, 2018, to list. The slow transition between Solar Cycle 24 and Solar Cycle 25 appears to be underway.
What does this mean? First, it suggests that the solar cycle is still operative. This contradicts widespread internet buzz that a Grand Minimum is in the offing, with no new sunspots expected for decades as the solar cycle grinds to a halt. Second, if patterns of previous solar cycles hold, Solar Minimum is not finished. It will probably continue to deepen in the year or so ahead even as new Solar Cycle 25 sunspots occasionally pop up, promising an ultimate end to the lassitude.
The Next Grand Minimum 
There were accountable sunspots even during a few periods of the Maunder Minimum. The question is the instruments of that time were not able to identify tiny and ephemeral ones. Some experts say with present instruments they would have been able to check for sunspots with 15 times more accuracy than the old instruments. In fact other solar decaying parameters show we are still going down SC24 with a TSI reaching the lowest values of the last 70 years. The possibility of a grand minimum even worst than Maunder’s is far from being discarded with the present values of solar parameters.
It would be more meaningful if someone could determine the smallest visible sunspot possible during the Maunder Minimum with the equipment they had at that time; then, use that minimum size to eliminate current reported sunspots that are reported using today’s high powered equipment.
That way we could have an apples-to-apples comparison as to how today’s minimums compare to Maunder & Dalton minimums.
Steven, excellent point. This is one that I have wondered about for a long time. There have been some adjustments to the number of spots over time, but I do not remember the criteria.