Sunday, October 6, 2019


Solar Minimum is here, and it is very deep. During this quiet nadir of solar activity, something happens that might surprise you: Two solar cycles become active at the same time. Yesterday's sun displayed this counter-intuitive phenomenon:

An extreme UV image of the sun with magnetic field maps inset. Credit: NASA/SDO

This image from NASA's Solar Dynamics Observatory shows two active regions on the sun--one north of the equator and once south. These are not sunspots. Instead, they are "hot spots" where magnetic fields have gathered with just enough intensity to bottle-up some glowing-hot plasma, but not quite enough strength to create a full-fledged sunspot.

The magnetic polarity of these two hot spots identifies them as members of different solar cycles (see: Hale's Law). The southern hot spot comes from old Solar Cycle 24. The northern hot spot comes from new Solar Cycle 25. Adjacent solar cycles always overlap during Solar
Minimum and, indeed, this is happening right now.

If forecasters are correct, Solar Cycle 25 will gain strength in the years ahead, ultimately dispatching old Solar Cycle 24. A new Solar Maximum comprised entirely of Solar Cycle 25 sunspots should arrive as early as 2023.

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