Sun Flattening Into Grand Minimum, Says Solar Physicist

With each passing season, the weather seems stranger and more extreme.

Who can argue with a sudden outbreak of the “polar vortex” phenomenon; unprecedented winter drought in California; and summer temperatures so torrid Down Under that even play at the Australian Open was briefly halted?

Is any of this connected to the sun’s drastically diminished recent sunspot cycles?

Weather isn’t climate, but circumstantial evidence indicates our sun may be entering a grand minimum of sunspot activity, not unlike the Maunder Minimum that some climatologists think caused record low winter temperatures in Northern Europe during the latter half of the 17th century.

“My opinion is that we are heading into a Maunder Minimum,” said Mark Giampapa, a solar physicist at the National Solar Observatory (NSO) in Tucson, Arizona. “I’m seeing a continuation in the decline of the sun’s mean magnetic field strengths and a weakening of the polar magnetic fields and subsurface flows.”

Theoretical details of how sunspots are actually produced continue to be debated. But one popular idea is that they are generated as the result of concentrated and twisted solar magnetic fields blocking internal convection in the outer third of the sun’s interior. This, in turn, gives the sunspots their dark appearance, since on average they are 2000 degrees cooler than the surrounding solar plasma.

These solar magnetic fields are thought to be triggered by the sun’s own internal “differential rotation.” That is, the fact that at various latitudes and depths, the sun’s gaseous plasma rotates at different rates. Then once these fields are produced, some theorists think it’s their interaction at the sun’s photosphere (or surface) that plays a crucial role in sunspot creation.

Even so, David Hathaway, a solar physicist at NASA Marshall Space Flight Center in Huntsville, says it’s the actual strength of such magnetic field at the end of a given maximum 11-year sunspot cycle that are thought to act as bellwethers for the size and strength of the next solar maximum.

“At the end of a sunspot cycle about all you have left are magnetic fields at the solar poles,” said Hathaway. “We’re at the sunspot maximum of Cycle 24. It’s the smallest sunspot cycle in 100 years and the third in a trend of diminishing sunspot cycles. So, Cycle 25 could likely be smaller than Cycle 24.”

Another indicator pointing to an imminent grand minimum is that the current solar cycle shows some signs of hemispheric asymmetry, says Steve Tobias, an applied mathematician at the University of Leeds in the U.K.

“When the field is about to enter a minimum or is leaving a minimum,” said Tobias, “we see more sunspots in one solar hemisphere than the other.”

Yet during the 1645 — 1715 Maunder Minimum itself, sunspots basically disappeared and as documented in paintings from the era, Northern Europe suffered unusually cold winter temperatures.  TRUNews