Last weekend, a small ephemeral sunspot appeared in the Sun's northern hemisphere, only to vanish a few hours later. The magnetic field of the spot was reversed, marking it as a member of the upcoming solar cycle (see data, e.g., HERE). Sunspot AR2727 appeared just north of the Sun’s equator. This sunspot still belongs to the decaying Solar Cycle #24, which peaked between 2012 and 2014. However, its magnetic polarity is already aligned with that of the other, yet unnumbered sunspot located at a higher latitude. These two sunspots have opposite magnetic polarities.
According to Hale's Law, this indicates that the two sunspots belong to different solar cycles. The high-latitude sunspot appears to be a harbinger of Solar Cycle #25. Solar cycles often blend at their boundaries. Indeed, ephemeral sunspots possibly linked to Solar Cycle #25 were reported on December 20, 2016, and April 8, 2018. Now, November 17, 2018, can be added to this list. The slow transition between Solar Cycle #24 and Solar Cycle #25 seems to be underway.
